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ffmpeg-filters(1)                                            ffmpeg-filters(1)




NAME

       ffmpeg-filters - FFmpeg filters


DESCRIPTION

       This document describes filters, sources, and sinks provided by the
       libavfilter library.


FILTERING INTRODUCTION

       Filtering in FFmpeg is enabled through the libavfilter library.

       In libavfilter, a filter can have multiple inputs and multiple outputs.
       To illustrate the sorts of things that are possible, we consider the
       following filtergraph.

                               [main]
               input --> split ---------------------> overlay --> output
                           |                             ^
                           |[tmp]                  [flip]|
                           +-----> crop --> vflip -------+

       This filtergraph splits the input stream in two streams, then sends one
       stream through the crop filter and the vflip filter, before merging it
       back with the other stream by overlaying it on top. You can use the
       following command to achieve this:

               ffmpeg -i INPUT -vf "split [main][tmp]; [tmp] crop=iw:ih/2:0:0, vflip [flip]; [main][flip] overlay=0:H/2" OUTPUT

       The result will be that the top half of the video is mirrored onto the
       bottom half of the output video.

       Filters in the same linear chain are separated by commas, and distinct
       linear chains of filters are separated by semicolons. In our example,
       crop,vflip are in one linear chain, split and overlay are separately in
       another. The points where the linear chains join are labelled by names
       enclosed in square brackets. In the example, the split filter generates
       two outputs that are associated to the labels [main] and [tmp].

       The stream sent to the second output of split, labelled as [tmp], is
       processed through the crop filter, which crops away the lower half part
       of the video, and then vertically flipped. The overlay filter takes in
       input the first unchanged output of the split filter (which was
       labelled as [main]), and overlay on its lower half the output generated
       by the crop,vflip filterchain.

       Some filters take in input a list of parameters: they are specified
       after the filter name and an equal sign, and are separated from each
       other by a colon.

       There exist so-called source filters that do not have an audio/video
       input, and sink filters that will not have audio/video output.


GRAPH

       The graph2dot program included in the FFmpeg tools directory can be
       used to parse a filtergraph description and issue a corresponding
       textual representation in the dot language.

       Invoke the command:

               graph2dot -h

       to see how to use graph2dot.

       You can then pass the dot description to the dot program (from the
       graphviz suite of programs) and obtain a graphical representation of
       the filtergraph.

       For example the sequence of commands:

               echo <GRAPH_DESCRIPTION> | \
               tools/graph2dot -o graph.tmp && \
               dot -Tpng graph.tmp -o graph.png && \
               display graph.png

       can be used to create and display an image representing the graph
       described by the GRAPH_DESCRIPTION string. Note that this string must
       be a complete self-contained graph, with its inputs and outputs
       explicitly defined.  For example if your command line is of the form:

               ffmpeg -i infile -vf scale=640:360 outfile

       your GRAPH_DESCRIPTION string will need to be of the form:

               nullsrc,scale=640:360,nullsink

       you may also need to set the nullsrc parameters and add a format filter
       in order to simulate a specific input file.


FILTERGRAPH DESCRIPTION

       A filtergraph is a directed graph of connected filters. It can contain
       cycles, and there can be multiple links between a pair of filters. Each
       link has one input pad on one side connecting it to one filter from
       which it takes its input, and one output pad on the other side
       connecting it to one filter accepting its output.

       Each filter in a filtergraph is an instance of a filter class
       registered in the application, which defines the features and the
       number of input and output pads of the filter.

       A filter with no input pads is called a "source", and a filter with no
       output pads is called a "sink".

   Filtergraph syntax
       A filtergraph has a textual representation, which is recognized by the
       -filter/-vf/-af and -filter_complex options in ffmpeg and -vf/-af in
       ffplay, and by the "avfilter_graph_parse_ptr()" function defined in
       libavfilter/avfilter.h.

       A filterchain consists of a sequence of connected filters, each one
       connected to the previous one in the sequence. A filterchain is
       represented by a list of ","-separated filter descriptions.

       A filtergraph consists of a sequence of filterchains. A sequence of
       filterchains is represented by a list of ";"-separated filterchain
       descriptions.

       A filter is represented by a string of the form:
       [in_link_1]...[in_link_N]filter_name@id=arguments[out_link_1]...[out_link_M]

       filter_name is the name of the filter class of which the described
       filter is an instance of, and has to be the name of one of the filter
       classes registered in the program optionally followed by "@id".  The
       name of the filter class is optionally followed by a string
       "=arguments".

       arguments is a string which contains the parameters used to initialize
       the filter instance. It may have one of two forms:

       o   A ':'-separated list of key=value pairs.

       o   A ':'-separated list of value. In this case, the keys are assumed
           to be the option names in the order they are declared. E.g. the
           "fade" filter declares three options in this order -- type,
           start_frame and nb_frames. Then the parameter list in:0:30 means
           that the value in is assigned to the option type, 0 to start_frame
           and 30 to nb_frames.

       o   A ':'-separated list of mixed direct value and long key=value
           pairs. The direct value must precede the key=value pairs, and
           follow the same constraints order of the previous point. The
           following key=value pairs can be set in any preferred order.

       If the option value itself is a list of items (e.g. the "format" filter
       takes a list of pixel formats), the items in the list are usually
       separated by |.

       The list of arguments can be quoted using the character ' as initial
       and ending mark, and the character \ for escaping the characters within
       the quoted text; otherwise the argument string is considered terminated
       when the next special character (belonging to the set []=;,) is
       encountered.

       The name and arguments of the filter are optionally preceded and
       followed by a list of link labels.  A link label allows one to name a
       link and associate it to a filter output or input pad. The preceding
       labels in_link_1 ... in_link_N, are associated to the filter input
       pads, the following labels out_link_1 ... out_link_M, are associated to
       the output pads.

       When two link labels with the same name are found in the filtergraph, a
       link between the corresponding input and output pad is created.

       If an output pad is not labelled, it is linked by default to the first
       unlabelled input pad of the next filter in the filterchain.  For
       example in the filterchain

               nullsrc, split[L1], [L2]overlay, nullsink

       the split filter instance has two output pads, and the overlay filter
       instance two input pads. The first output pad of split is labelled
       "L1", the first input pad of overlay is labelled "L2", and the second
       output pad of split is linked to the second input pad of overlay, which
       are both unlabelled.

       In a filter description, if the input label of the first filter is not
       specified, "in" is assumed; if the output label of the last filter is
       not specified, "out" is assumed.

       In a complete filterchain all the unlabelled filter input and output
       pads must be connected. A filtergraph is considered valid if all the
       filter input and output pads of all the filterchains are connected.

       Libavfilter will automatically insert scale filters where format
       conversion is required. It is possible to specify swscale flags for
       those automatically inserted scalers by prepending "sws_flags=flags;"
       to the filtergraph description.

       Here is a BNF description of the filtergraph syntax:

               <NAME>             ::= sequence of alphanumeric characters and '_'
               <FILTER_NAME>      ::= <NAME>["@"<NAME>]
               <LINKLABEL>        ::= "[" <NAME> "]"
               <LINKLABELS>       ::= <LINKLABEL> [<LINKLABELS>]
               <FILTER_ARGUMENTS> ::= sequence of chars (possibly quoted)
               <FILTER>           ::= [<LINKLABELS>] <FILTER_NAME> ["=" <FILTER_ARGUMENTS>] [<LINKLABELS>]
               <FILTERCHAIN>      ::= <FILTER> [,<FILTERCHAIN>]
               <FILTERGRAPH>      ::= [sws_flags=<flags>;] <FILTERCHAIN> [;<FILTERGRAPH>]

   Notes on filtergraph escaping
       Filtergraph description composition entails several levels of escaping.
       See the "Quoting and escaping" section in the ffmpeg-utils(1) manual
       for more information about the employed escaping procedure.

       A first level escaping affects the content of each filter option value,
       which may contain the special character ":" used to separate values, or
       one of the escaping characters "\'".

       A second level escaping affects the whole filter description, which may
       contain the escaping characters "\'" or the special characters "[],;"
       used by the filtergraph description.

       Finally, when you specify a filtergraph on a shell commandline, you
       need to perform a third level escaping for the shell special characters
       contained within it.

       For example, consider the following string to be embedded in the
       drawtext filter description text value:

               this is a 'string': may contain one, or more, special characters

       This string contains the "'" special escaping character, and the ":"
       special character, so it needs to be escaped in this way:

               text=this is a \'string\'\: may contain one, or more, special characters

       A second level of escaping is required when embedding the filter
       description in a filtergraph description, in order to escape all the
       filtergraph special characters. Thus the example above becomes:

               drawtext=text=this is a \\\'string\\\'\\: may contain one\, or more\, special characters

       (note that in addition to the "\'" escaping special characters, also
       "," needs to be escaped).

       Finally an additional level of escaping is needed when writing the
       filtergraph description in a shell command, which depends on the
       escaping rules of the adopted shell. For example, assuming that "\" is
       special and needs to be escaped with another "\", the previous string
       will finally result in:

               -vf "drawtext=text=this is a \\\\\\'string\\\\\\'\\\\: may contain one\\, or more\\, special characters"


TIMELINE EDITING

       Some filters support a generic enable option. For the filters
       supporting timeline editing, this option can be set to an expression
       which is evaluated before sending a frame to the filter. If the
       evaluation is non-zero, the filter will be enabled, otherwise the frame
       will be sent unchanged to the next filter in the filtergraph.

       The expression accepts the following values:

       t   timestamp expressed in seconds, NAN if the input timestamp is
           unknown

       n   sequential number of the input frame, starting from 0

       pos the position in the file of the input frame, NAN if unknown

       w
       h   width and height of the input frame if video

       Additionally, these filters support an enable command that can be used
       to re-define the expression.

       Like any other filtering option, the enable option follows the same
       rules.

       For example, to enable a blur filter (smartblur) from 10 seconds to 3
       minutes, and a curves filter starting at 3 seconds:

               smartblur = enable='between(t,10,3*60)',
               curves    = enable='gte(t,3)' : preset=cross_process

       See "ffmpeg -filters" to view which filters have timeline support.


CHANGING OPTIONS AT RUNTIME WITH A COMMAND

       Some options can be changed during the operation of the filter using a
       command. These options are marked 'T' on the output of ffmpeg -h
       filter=<name of filter>.  The name of the command is the name of the
       option and the argument is the new value.


OPTIONS FOR FILTERS WITH SEVERAL INPUTS

       Some filters with several inputs support a common set of options.
       These options can only be set by name, not with the short notation.

       eof_action
           The action to take when EOF is encountered on the secondary input;
           it accepts one of the following values:

           repeat
               Repeat the last frame (the default).

           endall
               End both streams.

           pass
               Pass the main input through.

       shortest
           If set to 1, force the output to terminate when the shortest input
           terminates. Default value is 0.

       repeatlast
           If set to 1, force the filter to extend the last frame of secondary
           streams until the end of the primary stream. A value of 0 disables
           this behavior.  Default value is 1.


AUDIO FILTERS

       When you configure your FFmpeg build, you can disable any of the
       existing filters using "--disable-filters".  The configure output will
       show the audio filters included in your build.

       Below is a description of the currently available audio filters.

   acompressor
       A compressor is mainly used to reduce the dynamic range of a signal.
       Especially modern music is mostly compressed at a high ratio to improve
       the overall loudness. It's done to get the highest attention of a
       listener, "fatten" the sound and bring more "power" to the track.  If a
       signal is compressed too much it may sound dull or "dead" afterwards or
       it may start to "pump" (which could be a powerful effect but can also
       destroy a track completely).  The right compression is the key to reach
       a professional sound and is the high art of mixing and mastering.
       Because of its complex settings it may take a long time to get the
       right feeling for this kind of effect.

       Compression is done by detecting the volume above a chosen level
       "threshold" and dividing it by the factor set with "ratio".  So if you
       set the threshold to -12dB and your signal reaches -6dB a ratio of 2:1
       will result in a signal at -9dB. Because an exact manipulation of the
       signal would cause distortion of the waveform the reduction can be
       levelled over the time. This is done by setting "Attack" and "Release".
       "attack" determines how long the signal has to rise above the threshold
       before any reduction will occur and "release" sets the time the signal
       has to fall below the threshold to reduce the reduction again. Shorter
       signals than the chosen attack time will be left untouched.  The
       overall reduction of the signal can be made up afterwards with the
       "makeup" setting. So compressing the peaks of a signal about 6dB and
       raising the makeup to this level results in a signal twice as loud than
       the source. To gain a softer entry in the compression the "knee"
       flattens the hard edge at the threshold in the range of the chosen
       decibels.

       The filter accepts the following options:

       level_in
           Set input gain. Default is 1. Range is between 0.015625 and 64.

       mode
           Set mode of compressor operation. Can be "upward" or "downward".
           Default is "downward".

       threshold
           If a signal of stream rises above this level it will affect the
           gain reduction.  By default it is 0.125. Range is between
           0.00097563 and 1.

       ratio
           Set a ratio by which the signal is reduced. 1:2 means that if the
           level rose 4dB above the threshold, it will be only 2dB above after
           the reduction.  Default is 2. Range is between 1 and 20.

       attack
           Amount of milliseconds the signal has to rise above the threshold
           before gain reduction starts. Default is 20. Range is between 0.01
           and 2000.

       release
           Amount of milliseconds the signal has to fall below the threshold
           before reduction is decreased again. Default is 250. Range is
           between 0.01 and 9000.

       makeup
           Set the amount by how much signal will be amplified after
           processing.  Default is 1. Range is from 1 to 64.

       knee
           Curve the sharp knee around the threshold to enter gain reduction
           more softly.  Default is 2.82843. Range is between 1 and 8.

       link
           Choose if the "average" level between all channels of input stream
           or the louder("maximum") channel of input stream affects the
           reduction. Default is "average".

       detection
           Should the exact signal be taken in case of "peak" or an RMS one in
           case of "rms". Default is "rms" which is mostly smoother.

       mix How much to use compressed signal in output. Default is 1.  Range
           is between 0 and 1.

       Commands

       This filter supports the all above options as commands.

   acontrast
       Simple audio dynamic range compression/expansion filter.

       The filter accepts the following options:

       contrast
           Set contrast. Default is 33. Allowed range is between 0 and 100.

   acopy
       Copy the input audio source unchanged to the output. This is mainly
       useful for testing purposes.

   acrossfade
       Apply cross fade from one input audio stream to another input audio
       stream.  The cross fade is applied for specified duration near the end
       of first stream.

       The filter accepts the following options:

       nb_samples, ns
           Specify the number of samples for which the cross fade effect has
           to last.  At the end of the cross fade effect the first input audio
           will be completely silent. Default is 44100.

       duration, d
           Specify the duration of the cross fade effect. See the Time
           duration section in the ffmpeg-utils(1) manual for the accepted
           syntax.  By default the duration is determined by nb_samples.  If
           set this option is used instead of nb_samples.

       overlap, o
           Should first stream end overlap with second stream start. Default
           is enabled.

       curve1
           Set curve for cross fade transition for first stream.

       curve2
           Set curve for cross fade transition for second stream.

           For description of available curve types see afade filter
           description.

       Examples

       o   Cross fade from one input to another:

                   ffmpeg -i first.flac -i second.flac -filter_complex acrossfade=d=10:c1=exp:c2=exp output.flac

       o   Cross fade from one input to another but without overlapping:

                   ffmpeg -i first.flac -i second.flac -filter_complex acrossfade=d=10:o=0:c1=exp:c2=exp output.flac

   acrossover
       Split audio stream into several bands.

       This filter splits audio stream into two or more frequency ranges.
       Summing all streams back will give flat output.

       The filter accepts the following options:

       split
           Set split frequencies. Those must be positive and increasing.

       order
           Set filter order for each band split. This controls filter roll-off
           or steepness of filter transfer function.  Available values are:

           2nd 12 dB per octave.

           4th 24 dB per octave.

           6th 36 dB per octave.

           8th 48 dB per octave.

           10th
               60 dB per octave.

           12th
               72 dB per octave.

           14th
               84 dB per octave.

           16th
               96 dB per octave.

           18th
               108 dB per octave.

           20th
               120 dB per octave.

           Default is 4th.

       level
           Set input gain level. Allowed range is from 0 to 1. Default value
           is 1.

       gains
           Set output gain for each band. Default value is 1 for all bands.

       Examples

       o   Split input audio stream into two bands (low and high) with split
           frequency of 1500 Hz, each band will be in separate stream:

                   ffmpeg -i in.flac -filter_complex 'acrossover=split=1500[LOW][HIGH]' -map '[LOW]' low.wav -map '[HIGH]' high.wav

       o   Same as above, but with higher filter order:

                   ffmpeg -i in.flac -filter_complex 'acrossover=split=1500:order=8th[LOW][HIGH]' -map '[LOW]' low.wav -map '[HIGH]' high.wav

       o   Same as above, but also with additional middle band (frequencies
           between 1500 and 8000):

                   ffmpeg -i in.flac -filter_complex 'acrossover=split=1500 8000:order=8th[LOW][MID][HIGH]' -map '[LOW]' low.wav -map '[MID]' mid.wav -map '[HIGH]' high.wav

   acrusher
       Reduce audio bit resolution.

       This filter is bit crusher with enhanced functionality. A bit crusher
       is used to audibly reduce number of bits an audio signal is sampled
       with. This doesn't change the bit depth at all, it just produces the
       effect. Material reduced in bit depth sounds more harsh and "digital".
       This filter is able to even round to continuous values instead of
       discrete bit depths.  Additionally it has a D/C offset which results in
       different crushing of the lower and the upper half of the signal.  An
       Anti-Aliasing setting is able to produce "softer" crushing sounds.

       Another feature of this filter is the logarithmic mode.  This setting
       switches from linear distances between bits to logarithmic ones.  The
       result is a much more "natural" sounding crusher which doesn't gate low
       signals for example. The human ear has a logarithmic perception, so
       this kind of crushing is much more pleasant.  Logarithmic crushing is
       also able to get anti-aliased.

       The filter accepts the following options:

       level_in
           Set level in.

       level_out
           Set level out.

       bits
           Set bit reduction.

       mix Set mixing amount.

       mode
           Can be linear: "lin" or logarithmic: "log".

       dc  Set DC.

       aa  Set anti-aliasing.

       samples
           Set sample reduction.

       lfo Enable LFO. By default disabled.

       lforange
           Set LFO range.

       lforate
           Set LFO rate.

       Commands

       This filter supports the all above options as commands.

   acue
       Delay audio filtering until a given wallclock timestamp. See the cue
       filter.

   adeclick
       Remove impulsive noise from input audio.

       Samples detected as impulsive noise are replaced by interpolated
       samples using autoregressive modelling.

       window, w
           Set window size, in milliseconds. Allowed range is from 10 to 100.
           Default value is 55 milliseconds.  This sets size of window which
           will be processed at once.

       overlap, o
           Set window overlap, in percentage of window size. Allowed range is
           from 50 to 95. Default value is 75 percent.  Setting this to a very
           high value increases impulsive noise removal but makes whole
           process much slower.

       arorder, a
           Set autoregression order, in percentage of window size. Allowed
           range is from 0 to 25. Default value is 2 percent. This option also
           controls quality of interpolated samples using neighbour good
           samples.

       threshold, t
           Set threshold value. Allowed range is from 1 to 100.  Default value
           is 2.  This controls the strength of impulsive noise which is going
           to be removed.  The lower value, the more samples will be detected
           as impulsive noise.

       burst, b
           Set burst fusion, in percentage of window size. Allowed range is 0
           to 10. Default value is 2.  If any two samples detected as noise
           are spaced less than this value then any sample between those two
           samples will be also detected as noise.

       method, m
           Set overlap method.

           It accepts the following values:

           add, a
               Select overlap-add method. Even not interpolated samples are
               slightly changed with this method.

           save, s
               Select overlap-save method. Not interpolated samples remain
               unchanged.

           Default value is "a".

   adeclip
       Remove clipped samples from input audio.

       Samples detected as clipped are replaced by interpolated samples using
       autoregressive modelling.

       window, w
           Set window size, in milliseconds. Allowed range is from 10 to 100.
           Default value is 55 milliseconds.  This sets size of window which
           will be processed at once.

       overlap, o
           Set window overlap, in percentage of window size. Allowed range is
           from 50 to 95. Default value is 75 percent.

       arorder, a
           Set autoregression order, in percentage of window size. Allowed
           range is from 0 to 25. Default value is 8 percent. This option also
           controls quality of interpolated samples using neighbour good
           samples.

       threshold, t
           Set threshold value. Allowed range is from 1 to 100.  Default value
           is 10. Higher values make clip detection less aggressive.

       hsize, n
           Set size of histogram used to detect clips. Allowed range is from
           100 to 9999.  Default value is 1000. Higher values make clip
           detection less aggressive.

       method, m
           Set overlap method.

           It accepts the following values:

           add, a
               Select overlap-add method. Even not interpolated samples are
               slightly changed with this method.

           save, s
               Select overlap-save method. Not interpolated samples remain
               unchanged.

           Default value is "a".

   adelay
       Delay one or more audio channels.

       Samples in delayed channel are filled with silence.

       The filter accepts the following option:

       delays
           Set list of delays in milliseconds for each channel separated by
           '|'.  Unused delays will be silently ignored. If number of given
           delays is smaller than number of channels all remaining channels
           will not be delayed.  If you want to delay exact number of samples,
           append 'S' to number.  If you want instead to delay in seconds,
           append 's' to number.

       all Use last set delay for all remaining channels. By default is
           disabled.  This option if enabled changes how option "delays" is
           interpreted.

       Examples

       o   Delay first channel by 1.5 seconds, the third channel by 0.5
           seconds and leave the second channel (and any other channels that
           may be present) unchanged.

                   adelay=1500|0|500

       o   Delay second channel by 500 samples, the third channel by 700
           samples and leave the first channel (and any other channels that
           may be present) unchanged.

                   adelay=0|500S|700S

       o   Delay all channels by same number of samples:

                   adelay=delays=64S:all=1

   adenorm
       Remedy denormals in audio by adding extremely low-level noise.

       This filter shall be placed before any filter that can produce
       denormals.

       A description of the accepted parameters follows.

       level
           Set level of added noise in dB. Default is "-351".  Allowed range
           is from -451 to -90.

       type
           Set type of added noise.

           dc  Add DC signal.

           ac  Add AC signal.

           square
               Add square signal.

           pulse
               Add pulse signal.

           Default is "dc".

       Commands

       This filter supports the all above options as commands.

   aderivative, aintegral
       Compute derivative/integral of audio stream.

       Applying both filters one after another produces original audio.

   aecho
       Apply echoing to the input audio.

       Echoes are reflected sound and can occur naturally amongst mountains
       (and sometimes large buildings) when talking or shouting; digital echo
       effects emulate this behaviour and are often used to help fill out the
       sound of a single instrument or vocal. The time difference between the
       original signal and the reflection is the "delay", and the loudness of
       the reflected signal is the "decay".  Multiple echoes can have
       different delays and decays.

       A description of the accepted parameters follows.

       in_gain
           Set input gain of reflected signal. Default is 0.6.

       out_gain
           Set output gain of reflected signal. Default is 0.3.

       delays
           Set list of time intervals in milliseconds between original signal
           and reflections separated by '|'. Allowed range for each "delay" is
           "(0 - 90000.0]".  Default is 1000.

       decays
           Set list of loudness of reflected signals separated by '|'.
           Allowed range for each "decay" is "(0 - 1.0]".  Default is 0.5.

       Examples

       o   Make it sound as if there are twice as many instruments as are
           actually playing:

                   aecho=0.8:0.88:60:0.4

       o   If delay is very short, then it sounds like a (metallic) robot
           playing music:

                   aecho=0.8:0.88:6:0.4

       o   A longer delay will sound like an open air concert in the
           mountains:

                   aecho=0.8:0.9:1000:0.3

       o   Same as above but with one more mountain:

                   aecho=0.8:0.9:1000|1800:0.3|0.25

   aemphasis
       Audio emphasis filter creates or restores material directly taken from
       LPs or emphased CDs with different filter curves. E.g. to store music
       on vinyl the signal has to be altered by a filter first to even out the
       disadvantages of this recording medium.  Once the material is played
       back the inverse filter has to be applied to restore the distortion of
       the frequency response.

       The filter accepts the following options:

       level_in
           Set input gain.

       level_out
           Set output gain.

       mode
           Set filter mode. For restoring material use "reproduction" mode,
           otherwise use "production" mode. Default is "reproduction" mode.

       type
           Set filter type. Selects medium. Can be one of the following:

           col select Columbia.

           emi select EMI.

           bsi select BSI (78RPM).

           riaa
               select RIAA.

           cd  select Compact Disc (CD).

           50fm
               select 50Xs (FM).

           75fm
               select 75Xs (FM).

           50kf
               select 50Xs (FM-KF).

           75kf
               select 75Xs (FM-KF).

       Commands

       This filter supports the all above options as commands.

   aeval
       Modify an audio signal according to the specified expressions.

       This filter accepts one or more expressions (one for each channel),
       which are evaluated and used to modify a corresponding audio signal.

       It accepts the following parameters:

       exprs
           Set the '|'-separated expressions list for each separate channel.
           If the number of input channels is greater than the number of
           expressions, the last specified expression is used for the
           remaining output channels.

       channel_layout, c
           Set output channel layout. If not specified, the channel layout is
           specified by the number of expressions. If set to same, it will use
           by default the same input channel layout.

       Each expression in exprs can contain the following constants and
       functions:

       ch  channel number of the current expression

       n   number of the evaluated sample, starting from 0

       s   sample rate

       t   time of the evaluated sample expressed in seconds

       nb_in_channels
       nb_out_channels
           input and output number of channels

       val(CH)
           the value of input channel with number CH

       Note: this filter is slow. For faster processing you should use a
       dedicated filter.

       Examples

       o   Half volume:

                   aeval=val(ch)/2:c=same

       o   Invert phase of the second channel:

                   aeval=val(0)|-val(1)

   aexciter
       An exciter is used to produce high sound that is not present in the
       original signal. This is done by creating harmonic distortions of the
       signal which are restricted in range and added to the original signal.
       An Exciter raises the upper end of an audio signal without simply
       raising the higher frequencies like an equalizer would do to create a
       more "crisp" or "brilliant" sound.

       The filter accepts the following options:

       level_in
           Set input level prior processing of signal.  Allowed range is from
           0 to 64.  Default value is 1.

       level_out
           Set output level after processing of signal.  Allowed range is from
           0 to 64.  Default value is 1.

       amount
           Set the amount of harmonics added to original signal.  Allowed
           range is from 0 to 64.  Default value is 1.

       drive
           Set the amount of newly created harmonics.  Allowed range is from
           0.1 to 10.  Default value is 8.5.

       blend
           Set the octave of newly created harmonics.  Allowed range is from
           -10 to 10.  Default value is 0.

       freq
           Set the lower frequency limit of producing harmonics in Hz.
           Allowed range is from 2000 to 12000 Hz.  Default is 7500 Hz.

       ceil
           Set the upper frequency limit of producing harmonics.  Allowed
           range is from 9999 to 20000 Hz.  If value is lower than 10000 Hz no
           limit is applied.

       listen
           Mute the original signal and output only added harmonics.  By
           default is disabled.

       Commands

       This filter supports the all above options as commands.

   afade
       Apply fade-in/out effect to input audio.

       A description of the accepted parameters follows.

       type, t
           Specify the effect type, can be either "in" for fade-in, or "out"
           for a fade-out effect. Default is "in".

       start_sample, ss
           Specify the number of the start sample for starting to apply the
           fade effect. Default is 0.

       nb_samples, ns
           Specify the number of samples for which the fade effect has to
           last. At the end of the fade-in effect the output audio will have
           the same volume as the input audio, at the end of the fade-out
           transition the output audio will be silence. Default is 44100.

       start_time, st
           Specify the start time of the fade effect. Default is 0.  The value
           must be specified as a time duration; see the Time duration section
           in the ffmpeg-utils(1) manual for the accepted syntax.  If set this
           option is used instead of start_sample.

       duration, d
           Specify the duration of the fade effect. See the Time duration
           section in the ffmpeg-utils(1) manual for the accepted syntax.  At
           the end of the fade-in effect the output audio will have the same
           volume as the input audio, at the end of the fade-out transition
           the output audio will be silence.  By default the duration is
           determined by nb_samples.  If set this option is used instead of
           nb_samples.

       curve
           Set curve for fade transition.

           It accepts the following values:

           tri select triangular, linear slope (default)

           qsin
               select quarter of sine wave

           hsin
               select half of sine wave

           esin
               select exponential sine wave

           log select logarithmic

           ipar
               select inverted parabola

           qua select quadratic

           cub select cubic

           squ select square root

           cbr select cubic root

           par select parabola

           exp select exponential

           iqsin
               select inverted quarter of sine wave

           ihsin
               select inverted half of sine wave

           dese
               select double-exponential seat

           desi
               select double-exponential sigmoid

           losi
               select logistic sigmoid

           sinc
               select sine cardinal function

           isinc
               select inverted sine cardinal function

           nofade
               no fade applied

       Commands

       This filter supports the all above options as commands.

       Examples

       o   Fade in first 15 seconds of audio:

                   afade=t=in:ss=0:d=15

       o   Fade out last 25 seconds of a 900 seconds audio:

                   afade=t=out:st=875:d=25

   afftdn
       Denoise audio samples with FFT.

       A description of the accepted parameters follows.

       nr  Set the noise reduction in dB, allowed range is 0.01 to 97.
           Default value is 12 dB.

       nf  Set the noise floor in dB, allowed range is -80 to -20.  Default
           value is -50 dB.

       nt  Set the noise type.

           It accepts the following values:

           w   Select white noise.

           v   Select vinyl noise.

           s   Select shellac noise.

           c   Select custom noise, defined in "bn" option.

               Default value is white noise.

       bn  Set custom band noise for every one of 15 bands.  Bands are
           separated by ' ' or '|'.

       rf  Set the residual floor in dB, allowed range is -80 to -20.  Default
           value is -38 dB.

       tn  Enable noise tracking. By default is disabled.  With this enabled,
           noise floor is automatically adjusted.

       tr  Enable residual tracking. By default is disabled.

       om  Set the output mode.

           It accepts the following values:

           i   Pass input unchanged.

           o   Pass noise filtered out.

           n   Pass only noise.

               Default value is o.

       Commands

       This filter supports the following commands:

       sample_noise, sn
           Start or stop measuring noise profile.  Syntax for the command is :
           "start" or "stop" string.  After measuring noise profile is stopped
           it will be automatically applied in filtering.

       noise_reduction, nr
           Change noise reduction. Argument is single float number.  Syntax
           for the command is : "noise_reduction"

       noise_floor, nf
           Change noise floor. Argument is single float number.  Syntax for
           the command is : "noise_floor"

       output_mode, om
           Change output mode operation.  Syntax for the command is : "i", "o"
           or "n" string.

   afftfilt
       Apply arbitrary expressions to samples in frequency domain.

       real
           Set frequency domain real expression for each separate channel
           separated by '|'. Default is "re".  If the number of input channels
           is greater than the number of expressions, the last specified
           expression is used for the remaining output channels.

       imag
           Set frequency domain imaginary expression for each separate channel
           separated by '|'. Default is "im".

           Each expression in real and imag can contain the following
           constants and functions:

           sr  sample rate

           b   current frequency bin number

           nb  number of available bins

           ch  channel number of the current expression

           chs number of channels

           pts current frame pts

           re  current real part of frequency bin of current channel

           im  current imaginary part of frequency bin of current channel

           real(b, ch)
               Return the value of real part of frequency bin at location
               (bin,channel)

           imag(b, ch)
               Return the value of imaginary part of frequency bin at location
               (bin,channel)

       win_size
           Set window size. Allowed range is from 16 to 131072.  Default is
           4096

       win_func
           Set window function. Default is "hann".

       overlap
           Set window overlap. If set to 1, the recommended overlap for
           selected window function will be picked. Default is 0.75.

       Examples

       o   Leave almost only low frequencies in audio:

                   afftfilt="'real=re * (1-clip((b/nb)*b,0,1))':imag='im * (1-clip((b/nb)*b,0,1))'"

       o   Apply robotize effect:

                   afftfilt="real='hypot(re,im)*sin(0)':imag='hypot(re,im)*cos(0)':win_size=512:overlap=0.75"

       o   Apply whisper effect:

                   afftfilt="real='hypot(re,im)*cos((random(0)*2-1)*2*3.14)':imag='hypot(re,im)*sin((random(1)*2-1)*2*3.14)':win_size=128:overlap=0.8"

   afir
       Apply an arbitrary Finite Impulse Response filter.

       This filter is designed for applying long FIR filters, up to 60 seconds
       long.

       It can be used as component for digital crossover filters, room
       equalization, cross talk cancellation, wavefield synthesis,
       auralization, ambiophonics, ambisonics and spatialization.

       This filter uses the streams higher than first one as FIR coefficients.
       If the non-first stream holds a single channel, it will be used for all
       input channels in the first stream, otherwise the number of channels in
       the non-first stream must be same as the number of channels in the
       first stream.

       It accepts the following parameters:

       dry Set dry gain. This sets input gain.

       wet Set wet gain. This sets final output gain.

       length
           Set Impulse Response filter length. Default is 1, which means whole
           IR is processed.

       gtype
           Enable applying gain measured from power of IR.

           Set which approach to use for auto gain measurement.

           none
               Do not apply any gain.

           peak
               select peak gain, very conservative approach. This is default
               value.

           dc  select DC gain, limited application.

           gn  select gain to noise approach, this is most popular one.

       irgain
           Set gain to be applied to IR coefficients before filtering.
           Allowed range is 0 to 1. This gain is applied after any gain
           applied with gtype option.

       irfmt
           Set format of IR stream. Can be "mono" or "input".  Default is
           "input".

       maxir
           Set max allowed Impulse Response filter duration in seconds.
           Default is 30 seconds.  Allowed range is 0.1 to 60 seconds.

       response
           Show IR frequency response, magnitude(magenta), phase(green) and
           group delay(yellow) in additional video stream.  By default it is
           disabled.

       channel
           Set for which IR channel to display frequency response. By default
           is first channel displayed. This option is used only when response
           is enabled.

       size
           Set video stream size. This option is used only when response is
           enabled.

       rate
           Set video stream frame rate. This option is used only when response
           is enabled.

       minp
           Set minimal partition size used for convolution. Default is 8192.
           Allowed range is from 1 to 32768.  Lower values decreases latency
           at cost of higher CPU usage.

       maxp
           Set maximal partition size used for convolution. Default is 8192.
           Allowed range is from 8 to 32768.  Lower values may increase CPU
           usage.

       nbirs
           Set number of input impulse responses streams which will be
           switchable at runtime.  Allowed range is from 1 to 32. Default is
           1.

       ir  Set IR stream which will be used for convolution, starting from 0,
           should always be lower than supplied value by "nbirs" option.
           Default is 0.  This option can be changed at runtime via commands.

       Examples

       o   Apply reverb to stream using mono IR file as second input, complete
           command using ffmpeg:

                   ffmpeg -i input.wav -i middle_tunnel_1way_mono.wav -lavfi afir output.wav

   aformat
       Set output format constraints for the input audio. The framework will
       negotiate the most appropriate format to minimize conversions.

       It accepts the following parameters:

       sample_fmts, f
           A '|'-separated list of requested sample formats.

       sample_rates, r
           A '|'-separated list of requested sample rates.

       channel_layouts, cl
           A '|'-separated list of requested channel layouts.

           See the Channel Layout section in the ffmpeg-utils(1) manual for
           the required syntax.

       If a parameter is omitted, all values are allowed.

       Force the output to either unsigned 8-bit or signed 16-bit stereo

               aformat=sample_fmts=u8|s16:channel_layouts=stereo

   afreqshift
       Apply frequency shift to input audio samples.

       The filter accepts the following options:

       shift
           Specify frequency shift. Allowed range is -INT_MAX to INT_MAX.
           Default value is 0.0.

       level
           Set output gain applied to final output. Allowed range is from 0.0
           to 1.0.  Default value is 1.0.

       Commands

       This filter supports the all above options as commands.

   agate
       A gate is mainly used to reduce lower parts of a signal. This kind of
       signal processing reduces disturbing noise between useful signals.

       Gating is done by detecting the volume below a chosen level threshold
       and dividing it by the factor set with ratio. The bottom of the noise
       floor is set via range. Because an exact manipulation of the signal
       would cause distortion of the waveform the reduction can be levelled
       over time. This is done by setting attack and release.

       attack determines how long the signal has to fall below the threshold
       before any reduction will occur and release sets the time the signal
       has to rise above the threshold to reduce the reduction again.  Shorter
       signals than the chosen attack time will be left untouched.

       level_in
           Set input level before filtering.  Default is 1. Allowed range is
           from 0.015625 to 64.

       mode
           Set the mode of operation. Can be "upward" or "downward".  Default
           is "downward". If set to "upward" mode, higher parts of signal will
           be amplified, expanding dynamic range in upward direction.
           Otherwise, in case of "downward" lower parts of signal will be
           reduced.

       range
           Set the level of gain reduction when the signal is below the
           threshold.  Default is 0.06125. Allowed range is from 0 to 1.
           Setting this to 0 disables reduction and then filter behaves like
           expander.

       threshold
           If a signal rises above this level the gain reduction is released.
           Default is 0.125. Allowed range is from 0 to 1.

       ratio
           Set a ratio by which the signal is reduced.  Default is 2. Allowed
           range is from 1 to 9000.

       attack
           Amount of milliseconds the signal has to rise above the threshold
           before gain reduction stops.  Default is 20 milliseconds. Allowed
           range is from 0.01 to 9000.

       release
           Amount of milliseconds the signal has to fall below the threshold
           before the reduction is increased again. Default is 250
           milliseconds.  Allowed range is from 0.01 to 9000.

       makeup
           Set amount of amplification of signal after processing.  Default is
           1. Allowed range is from 1 to 64.

       knee
           Curve the sharp knee around the threshold to enter gain reduction
           more softly.  Default is 2.828427125. Allowed range is from 1 to 8.

       detection
           Choose if exact signal should be taken for detection or an RMS like
           one.  Default is "rms". Can be "peak" or "rms".

       link
           Choose if the average level between all channels or the louder
           channel affects the reduction.  Default is "average". Can be
           "average" or "maximum".

       Commands

       This filter supports the all above options as commands.

   aiir
       Apply an arbitrary Infinite Impulse Response filter.

       It accepts the following parameters:

       zeros, z
           Set B/numerator/zeros/reflection coefficients.

       poles, p
           Set A/denominator/poles/ladder coefficients.

       gains, k
           Set channels gains.

       dry_gain
           Set input gain.

       wet_gain
           Set output gain.

       format, f
           Set coefficients format.

           ll  lattice-ladder function

           sf  analog transfer function

           tf  digital transfer function

           zp  Z-plane zeros/poles, cartesian (default)

           pr  Z-plane zeros/poles, polar radians

           pd  Z-plane zeros/poles, polar degrees

           sp  S-plane zeros/poles

       process, r
           Set type of processing.

           d   direct processing

           s   serial processing

           p   parallel processing

       precision, e
           Set filtering precision.

           dbl double-precision floating-point (default)

           flt single-precision floating-point

           i32 32-bit integers

           i16 16-bit integers

       normalize, n
           Normalize filter coefficients, by default is enabled.  Enabling it
           will normalize magnitude response at DC to 0dB.

       mix How much to use filtered signal in output. Default is 1.  Range is
           between 0 and 1.

       response
           Show IR frequency response, magnitude(magenta), phase(green) and
           group delay(yellow) in additional video stream.  By default it is
           disabled.

       channel
           Set for which IR channel to display frequency response. By default
           is first channel displayed. This option is used only when response
           is enabled.

       size
           Set video stream size. This option is used only when response is
           enabled.

       Coefficients in "tf" and "sf" format are separated by spaces and are in
       ascending order.

       Coefficients in "zp" format are separated by spaces and order of
       coefficients doesn't matter. Coefficients in "zp" format are complex
       numbers with i imaginary unit.

       Different coefficients and gains can be provided for every channel, in
       such case use '|' to separate coefficients or gains. Last provided
       coefficients will be used for all remaining channels.

       Examples

       o   Apply 2 pole elliptic notch at around 5000Hz for 48000 Hz sample
           rate:

                   aiir=k=1:z=7.957584807809675810E-1 -2.575128568908332300 3.674839853930788710 -2.57512875289799137 7.957586296317130880E-1:p=1 -2.86950072432325953 3.63022088054647218 -2.28075678147272232 6.361362326477423500E-1:f=tf:r=d

       o   Same as above but in "zp" format:

                   aiir=k=0.79575848078096756:z=0.80918701+0.58773007i 0.80918701-0.58773007i 0.80884700+0.58784055i 0.80884700-0.58784055i:p=0.63892345+0.59951235i 0.63892345-0.59951235i 0.79582691+0.44198673i 0.79582691-0.44198673i:f=zp:r=s

       o   Apply 3-rd order analog normalized Butterworth low-pass filter,
           using analog transfer function format:

                   aiir=z=1.3057 0 0 0:p=1.3057 2.3892 2.1860 1:f=sf:r=d

   alimiter
       The limiter prevents an input signal from rising over a desired
       threshold.  This limiter uses lookahead technology to prevent your
       signal from distorting.  It means that there is a small delay after the
       signal is processed. Keep in mind that the delay it produces is the
       attack time you set.

       The filter accepts the following options:

       level_in
           Set input gain. Default is 1.

       level_out
           Set output gain. Default is 1.

       limit
           Don't let signals above this level pass the limiter. Default is 1.

       attack
           The limiter will reach its attenuation level in this amount of time
           in milliseconds. Default is 5 milliseconds.

       release
           Come back from limiting to attenuation 1.0 in this amount of
           milliseconds.  Default is 50 milliseconds.

       asc When gain reduction is always needed ASC takes care of releasing to
           an average reduction level rather than reaching a reduction of 0 in
           the release time.

       asc_level
           Select how much the release time is affected by ASC, 0 means nearly
           no changes in release time while 1 produces higher release times.

       level
           Auto level output signal. Default is enabled.  This normalizes
           audio back to 0dB if enabled.

       Depending on picked setting it is recommended to upsample input 2x or
       4x times with aresample before applying this filter.

   allpass
       Apply a two-pole all-pass filter with central frequency (in Hz)
       frequency, and filter-width width.  An all-pass filter changes the
       audio's frequency to phase relationship without changing its frequency
       to amplitude relationship.

       The filter accepts the following options:

       frequency, f
           Set frequency in Hz.

       width_type, t
           Set method to specify band-width of filter.

           h   Hz

           q   Q-Factor

           o   octave

           s   slope

           k   kHz

       width, w
           Specify the band-width of a filter in width_type units.

       mix, m
           How much to use filtered signal in output. Default is 1.  Range is
           between 0 and 1.

       channels, c
           Specify which channels to filter, by default all available are
           filtered.

       normalize, n
           Normalize biquad coefficients, by default is disabled.  Enabling it
           will normalize magnitude response at DC to 0dB.

       order, o
           Set the filter order, can be 1 or 2. Default is 2.

       transform, a
           Set transform type of IIR filter.

           di
           dii
           tdii
           latt
       precision, r
           Set precison of filtering.

           auto
               Pick automatic sample format depending on surround filters.

           s16 Always use signed 16-bit.

           s32 Always use signed 32-bit.

           f32 Always use float 32-bit.

           f64 Always use float 64-bit.

       Commands

       This filter supports the following commands:

       frequency, f
           Change allpass frequency.  Syntax for the command is : "frequency"

       width_type, t
           Change allpass width_type.  Syntax for the command is :
           "width_type"

       width, w
           Change allpass width.  Syntax for the command is : "width"

       mix, m
           Change allpass mix.  Syntax for the command is : "mix"

   aloop
       Loop audio samples.

       The filter accepts the following options:

       loop
           Set the number of loops. Setting this value to -1 will result in
           infinite loops.  Default is 0.

       size
           Set maximal number of samples. Default is 0.

       start
           Set first sample of loop. Default is 0.

   amerge
       Merge two or more audio streams into a single multi-channel stream.

       The filter accepts the following options:

       inputs
           Set the number of inputs. Default is 2.

       If the channel layouts of the inputs are disjoint, and therefore
       compatible, the channel layout of the output will be set accordingly
       and the channels will be reordered as necessary. If the channel layouts
       of the inputs are not disjoint, the output will have all the channels
       of the first input then all the channels of the second input, in that
       order, and the channel layout of the output will be the default value
       corresponding to the total number of channels.

       For example, if the first input is in 2.1 (FL+FR+LF) and the second
       input is FC+BL+BR, then the output will be in 5.1, with the channels in
       the following order: a1, a2, b1, a3, b2, b3 (a1 is the first channel of
       the first input, b1 is the first channel of the second input).

       On the other hand, if both input are in stereo, the output channels
       will be in the default order: a1, a2, b1, b2, and the channel layout
       will be arbitrarily set to 4.0, which may or may not be the expected
       value.

       All inputs must have the same sample rate, and format.

       If inputs do not have the same duration, the output will stop with the
       shortest.

       Examples

       o   Merge two mono files into a stereo stream:

                   amovie=left.wav [l] ; amovie=right.mp3 [r] ; [l] [r] amerge

       o   Multiple merges assuming 1 video stream and 6 audio streams in
           input.mkv:

                   ffmpeg -i input.mkv -filter_complex "[0:1][0:2][0:3][0:4][0:5][0:6] amerge=inputs=6" -c:a pcm_s16le output.mkv

   amix
       Mixes multiple audio inputs into a single output.

       Note that this filter only supports float samples (the amerge and pan
       audio filters support many formats). If the amix input has integer
       samples then aresample will be automatically inserted to perform the
       conversion to float samples.

       For example

               ffmpeg -i INPUT1 -i INPUT2 -i INPUT3 -filter_complex amix=inputs=3:duration=first:dropout_transition=3 OUTPUT

       will mix 3 input audio streams to a single output with the same
       duration as the first input and a dropout transition time of 3 seconds.

       It accepts the following parameters:

       inputs
           The number of inputs. If unspecified, it defaults to 2.

       duration
           How to determine the end-of-stream.

           longest
               The duration of the longest input. (default)

           shortest
               The duration of the shortest input.

           first
               The duration of the first input.

       dropout_transition
           The transition time, in seconds, for volume renormalization when an
           input stream ends. The default value is 2 seconds.

       weights
           Specify weight of each input audio stream as sequence.  Each weight
           is separated by space. By default all inputs have same weight.

       normalize
           Always scale inputs instead of only doing summation of samples.
           Beware of heavy clipping if inputs are not normalized prior or
           after filtering by this filter if this option is disabled. By
           default is enabled.

       Commands

       This filter supports the following commands:

       weights
       sum Syntax is same as option with same name.

   amultiply
       Multiply first audio stream with second audio stream and store result
       in output audio stream. Multiplication is done by multiplying each
       sample from first stream with sample at same position from second
       stream.

       With this element-wise multiplication one can create amplitude fades
       and amplitude modulations.

   anequalizer
       High-order parametric multiband equalizer for each channel.

       It accepts the following parameters:

       params
           This option string is in format: "cchn f=cf w=w g=g t=f | ..."
           Each equalizer band is separated by '|'.

           chn Set channel number to which equalization will be applied.  If
               input doesn't have that channel the entry is ignored.

           f   Set central frequency for band.  If input doesn't have that
               frequency the entry is ignored.

           w   Set band width in Hertz.

           g   Set band gain in dB.

           t   Set filter type for band, optional, can be:

               0   Butterworth, this is default.

               1   Chebyshev type 1.

               2   Chebyshev type 2.

       curves
           With this option activated frequency response of anequalizer is
           displayed in video stream.

       size
           Set video stream size. Only useful if curves option is activated.

       mgain
           Set max gain that will be displayed. Only useful if curves option
           is activated.  Setting this to a reasonable value makes it possible
           to display gain which is derived from neighbour bands which are too
           close to each other and thus produce higher gain when both are
           activated.

       fscale
           Set frequency scale used to draw frequency response in video
           output.  Can be linear or logarithmic. Default is logarithmic.

       colors
           Set color for each channel curve which is going to be displayed in
           video stream.  This is list of color names separated by space or by
           '|'.  Unrecognised or missing colors will be replaced by white
           color.

       Examples

       o   Lower gain by 10 of central frequency 200Hz and width 100 Hz for
           first 2 channels using Chebyshev type 1 filter:

                   anequalizer=c0 f=200 w=100 g=-10 t=1|c1 f=200 w=100 g=-10 t=1

       Commands

       This filter supports the following commands:

       change
           Alter existing filter parameters.  Syntax for the commands is :
           "fN|f=freq|w=width|g=gain"

           fN is existing filter number, starting from 0, if no such filter is
           available error is returned.  freq set new frequency parameter.
           width set new width parameter in Hertz.  gain set new gain
           parameter in dB.

           Full filter invocation with asendcmd may look like this:
           asendcmd=c='4.0 anequalizer change
           0|f=200|w=50|g=1',anequalizer=...

   anlmdn
       Reduce broadband noise in audio samples using Non-Local Means
       algorithm.

       Each sample is adjusted by looking for other samples with similar
       contexts. This context similarity is defined by comparing their
       surrounding patches of size p. Patches are searched in an area of r
       around the sample.

       The filter accepts the following options:

       s   Set denoising strength. Allowed range is from 0.00001 to 10.
           Default value is 0.00001.

       p   Set patch radius duration. Allowed range is from 1 to 100
           milliseconds.  Default value is 2 milliseconds.

       r   Set research radius duration. Allowed range is from 2 to 300
           milliseconds.  Default value is 6 milliseconds.

       o   Set the output mode.

           It accepts the following values:

           i   Pass input unchanged.

           o   Pass noise filtered out.

           n   Pass only noise.

               Default value is o.

       m   Set smooth factor. Default value is 11. Allowed range is from 1 to
           15.

       Commands

       This filter supports the all above options as commands.

   anlms
       Apply Normalized Least-Mean-Squares algorithm to the first audio stream
       using the second audio stream.

       This adaptive filter is used to mimic a desired filter by finding the
       filter coefficients that relate to producing the least mean square of
       the error signal (difference between the desired, 2nd input audio
       stream and the actual signal, the 1st input audio stream).

       A description of the accepted options follows.

       order
           Set filter order.

       mu  Set filter mu.

       eps Set the filter eps.

       leakage
           Set the filter leakage.

       out_mode
           It accepts the following values:

           i   Pass the 1st input.

           d   Pass the 2nd input.

           o   Pass filtered samples.

           n   Pass difference between desired and filtered samples.

               Default value is o.

       Examples

       o   One of many usages of this filter is noise reduction, input audio
           is filtered with same samples that are delayed by fixed amount, one
           such example for stereo audio is:

                   asplit[a][b],[a]adelay=32S|32S[a],[b][a]anlms=order=128:leakage=0.0005:mu=.5:out_mode=o

       Commands

       This filter supports the same commands as options, excluding option
       "order".

   anull
       Pass the audio source unchanged to the output.

   apad
       Pad the end of an audio stream with silence.

       This can be used together with ffmpeg -shortest to extend audio streams
       to the same length as the video stream.

       A description of the accepted options follows.

       packet_size
           Set silence packet size. Default value is 4096.

       pad_len
           Set the number of samples of silence to add to the end. After the
           value is reached, the stream is terminated. This option is mutually
           exclusive with whole_len.

       whole_len
           Set the minimum total number of samples in the output audio stream.
           If the value is longer than the input audio length, silence is
           added to the end, until the value is reached. This option is
           mutually exclusive with pad_len.

       pad_dur
           Specify the duration of samples of silence to add. See the Time
           duration section in the ffmpeg-utils(1) manual for the accepted
           syntax. Used only if set to non-zero value.

       whole_dur
           Specify the minimum total duration in the output audio stream. See
           the Time duration section in the ffmpeg-utils(1) manual for the
           accepted syntax. Used only if set to non-zero value. If the value
           is longer than the input audio length, silence is added to the end,
           until the value is reached.  This option is mutually exclusive with
           pad_dur

       If neither the pad_len nor the whole_len nor pad_dur nor whole_dur
       option is set, the filter will add silence to the end of the input
       stream indefinitely.

       Examples

       o   Add 1024 samples of silence to the end of the input:

                   apad=pad_len=1024

       o   Make sure the audio output will contain at least 10000 samples, pad
           the input with silence if required:

                   apad=whole_len=10000

       o   Use ffmpeg to pad the audio input with silence, so that the video
           stream will always result the shortest and will be converted until
           the end in the output file when using the shortest option:

                   ffmpeg -i VIDEO -i AUDIO -filter_complex "[1:0]apad" -shortest OUTPUT

   aphaser
       Add a phasing effect to the input audio.

       A phaser filter creates series of peaks and troughs in the frequency
       spectrum.  The position of the peaks and troughs are modulated so that
       they vary over time, creating a sweeping effect.

       A description of the accepted parameters follows.

       in_gain
           Set input gain. Default is 0.4.

       out_gain
           Set output gain. Default is 0.74

       delay
           Set delay in milliseconds. Default is 3.0.

       decay
           Set decay. Default is 0.4.

       speed
           Set modulation speed in Hz. Default is 0.5.

       type
           Set modulation type. Default is triangular.

           It accepts the following values:

           triangular, t
           sinusoidal, s

   aphaseshift
       Apply phase shift to input audio samples.

       The filter accepts the following options:

       shift
           Specify phase shift. Allowed range is from -1.0 to 1.0.  Default
           value is 0.0.

       level
           Set output gain applied to final output. Allowed range is from 0.0
           to 1.0.  Default value is 1.0.

       Commands

       This filter supports the all above options as commands.

   apulsator
       Audio pulsator is something between an autopanner and a tremolo.  But
       it can produce funny stereo effects as well. Pulsator changes the
       volume of the left and right channel based on a LFO (low frequency
       oscillator) with different waveforms and shifted phases.  This filter
       have the ability to define an offset between left and right channel. An
       offset of 0 means that both LFO shapes match each other.  The left and
       right channel are altered equally - a conventional tremolo.  An offset
       of 50% means that the shape of the right channel is exactly shifted in
       phase (or moved backwards about half of the frequency) - pulsator acts
       as an autopanner. At 1 both curves match again. Every setting in
       between moves the phase shift gapless between all stages and produces
       some "bypassing" sounds with sine and triangle waveforms. The more you
       set the offset near 1 (starting from the 0.5) the faster the signal
       passes from the left to the right speaker.

       The filter accepts the following options:

       level_in
           Set input gain. By default it is 1. Range is [0.015625 - 64].

       level_out
           Set output gain. By default it is 1. Range is [0.015625 - 64].

       mode
           Set waveform shape the LFO will use. Can be one of: sine, triangle,
           square, sawup or sawdown. Default is sine.

       amount
           Set modulation. Define how much of original signal is affected by
           the LFO.

       offset_l
           Set left channel offset. Default is 0. Allowed range is [0 - 1].

       offset_r
           Set right channel offset. Default is 0.5. Allowed range is [0 - 1].

       width
           Set pulse width. Default is 1. Allowed range is [0 - 2].

       timing
           Set possible timing mode. Can be one of: bpm, ms or hz. Default is
           hz.

       bpm Set bpm. Default is 120. Allowed range is [30 - 300]. Only used if
           timing is set to bpm.

       ms  Set ms. Default is 500. Allowed range is [10 - 2000]. Only used if
           timing is set to ms.

       hz  Set frequency in Hz. Default is 2. Allowed range is [0.01 - 100].
           Only used if timing is set to hz.

   aresample
       Resample the input audio to the specified parameters, using the
       libswresample library. If none are specified then the filter will
       automatically convert between its input and output.

       This filter is also able to stretch/squeeze the audio data to make it
       match the timestamps or to inject silence / cut out audio to make it
       match the timestamps, do a combination of both or do neither.

       The filter accepts the syntax [sample_rate:]resampler_options, where
       sample_rate expresses a sample rate and resampler_options is a list of
       key=value pairs, separated by ":". See the "Resampler Options" section
       in the ffmpeg-resampler(1) manual for the complete list of supported
       options.

       Examples

       o   Resample the input audio to 44100Hz:

                   aresample=44100

       o   Stretch/squeeze samples to the given timestamps, with a maximum of
           1000 samples per second compensation:

                   aresample=async=1000

   areverse
       Reverse an audio clip.

       Warning: This filter requires memory to buffer the entire clip, so
       trimming is suggested.

       Examples

       o   Take the first 5 seconds of a clip, and reverse it.

                   atrim=end=5,areverse

   arnndn
       Reduce noise from speech using Recurrent Neural Networks.

       This filter accepts the following options:

       model, m
           Set train model file to load. This option is always required.

       mix Set how much to mix filtered samples into final output.  Allowed
           range is from -1 to 1. Default value is 1.  Negative values are
           special, they set how much to keep filtered noise in the final
           filter output. Set this option to -1 to hear actual noise removed
           from input signal.

       Commands

       This filter supports the all above options as commands.

   asetnsamples
       Set the number of samples per each output audio frame.

       The last output packet may contain a different number of samples, as
       the filter will flush all the remaining samples when the input audio
       signals its end.

       The filter accepts the following options:

       nb_out_samples, n
           Set the number of frames per each output audio frame. The number is
           intended as the number of samples per each channel.  Default value
           is 1024.

       pad, p
           If set to 1, the filter will pad the last audio frame with zeroes,
           so that the last frame will contain the same number of samples as
           the previous ones. Default value is 1.

       For example, to set the number of per-frame samples to 1234 and disable
       padding for the last frame, use:

               asetnsamples=n=1234:p=0

   asetrate
       Set the sample rate without altering the PCM data.  This will result in
       a change of speed and pitch.

       The filter accepts the following options:

       sample_rate, r
           Set the output sample rate. Default is 44100 Hz.

   ashowinfo
       Show a line containing various information for each input audio frame.
       The input audio is not modified.

       The shown line contains a sequence of key/value pairs of the form
       key:value.

       The following values are shown in the output:

       n   The (sequential) number of the input frame, starting from 0.

       pts The presentation timestamp of the input frame, in time base units;
           the time base depends on the filter input pad, and is usually
           1/sample_rate.

       pts_time
           The presentation timestamp of the input frame in seconds.

       pos position of the frame in the input stream, -1 if this information
           in unavailable and/or meaningless (for example in case of synthetic
           audio)

       fmt The sample format.

       chlayout
           The channel layout.

       rate
           The sample rate for the audio frame.

       nb_samples
           The number of samples (per channel) in the frame.

       checksum
           The Adler-32 checksum (printed in hexadecimal) of the audio data.
           For planar audio, the data is treated as if all the planes were
           concatenated.

       plane_checksums
           A list of Adler-32 checksums for each data plane.

   asoftclip
       Apply audio soft clipping.

       Soft clipping is a type of distortion effect where the amplitude of a
       signal is saturated along a smooth curve, rather than the abrupt shape
       of hard-clipping.

       This filter accepts the following options:

       type
           Set type of soft-clipping.

           It accepts the following values:

           hard
           tanh
           atan
           cubic
           exp
           alg
           quintic
           sin
           erf
       threshold
           Set threshold from where to start clipping. Default value is 0dB or
           1.

       output
           Set gain applied to output. Default value is 0dB or 1.

       param
           Set additional parameter which controls sigmoid function.

       oversample
           Set oversampling factor.

       Commands

       This filter supports the all above options as commands.

   asr
       Automatic Speech Recognition

       This filter uses PocketSphinx for speech recognition. To enable
       compilation of this filter, you need to configure FFmpeg with
       "--enable-pocketsphinx".

       It accepts the following options:

       rate
           Set sampling rate of input audio. Defaults is 16000.  This need to
           match speech models, otherwise one will get poor results.

       hmm Set dictionary containing acoustic model files.

       dict
           Set pronunciation dictionary.

       lm  Set language model file.

       lmctl
           Set language model set.

       lmname
           Set which language model to use.

       logfn
           Set output for log messages.

       The filter exports recognized speech as the frame metadata
       "lavfi.asr.text".

   astats
       Display time domain statistical information about the audio channels.
       Statistics are calculated and displayed for each audio channel and,
       where applicable, an overall figure is also given.

       It accepts the following option:

       length
           Short window length in seconds, used for peak and trough RMS
           measurement.  Default is 0.05 (50 milliseconds). Allowed range is
           "[0.01 - 10]".

       metadata
           Set metadata injection. All the metadata keys are prefixed with
           "lavfi.astats.X", where "X" is channel number starting from 1 or
           string "Overall". Default is disabled.

           Available keys for each channel are: DC_offset Min_level Max_level
           Min_difference Max_difference Mean_difference RMS_difference
           Peak_level RMS_peak RMS_trough Crest_factor Flat_factor Peak_count
           Noise_floor Noise_floor_count Bit_depth Dynamic_range
           Zero_crossings Zero_crossings_rate Number_of_NaNs Number_of_Infs
           Number_of_denormals

           and for Overall: DC_offset Min_level Max_level Min_difference
           Max_difference Mean_difference RMS_difference Peak_level RMS_level
           RMS_peak RMS_trough Flat_factor Peak_count Noise_floor
           Noise_floor_count Bit_depth Number_of_samples Number_of_NaNs
           Number_of_Infs Number_of_denormals

           For example full key look like this "lavfi.astats.1.DC_offset" or
           this "lavfi.astats.Overall.Peak_count".

           For description what each key means read below.

       reset
           Set number of frame after which stats are going to be recalculated.
           Default is disabled.

       measure_perchannel
           Select the entries which need to be measured per channel. The
           metadata keys can be used as flags, default is all which measures
           everything.  none disables all per channel measurement.

       measure_overall
           Select the entries which need to be measured overall. The metadata
           keys can be used as flags, default is all which measures
           everything.  none disables all overall measurement.

       A description of each shown parameter follows:

       DC offset
           Mean amplitude displacement from zero.

       Min level
           Minimal sample level.

       Max level
           Maximal sample level.

       Min difference
           Minimal difference between two consecutive samples.

       Max difference
           Maximal difference between two consecutive samples.

       Mean difference
           Mean difference between two consecutive samples.  The average of
           each difference between two consecutive samples.

       RMS difference
           Root Mean Square difference between two consecutive samples.

       Peak level dB
       RMS level dB
           Standard peak and RMS level measured in dBFS.

       RMS peak dB
       RMS trough dB
           Peak and trough values for RMS level measured over a short window.

       Crest factor
           Standard ratio of peak to RMS level (note: not in dB).

       Flat factor
           Flatness (i.e. consecutive samples with the same value) of the
           signal at its peak levels (i.e. either Min level or Max level).

       Peak count
           Number of occasions (not the number of samples) that the signal
           attained either Min level or Max level.

       Noise floor dB
           Minimum local peak measured in dBFS over a short window.

       Noise floor count
           Number of occasions (not the number of samples) that the signal
           attained Noise floor.

       Bit depth
           Overall bit depth of audio. Number of bits used for each sample.

       Dynamic range
           Measured dynamic range of audio in dB.

       Zero crossings
           Number of points where the waveform crosses the zero level axis.

       Zero crossings rate
           Rate of Zero crossings and number of audio samples.

   asubboost
       Boost subwoofer frequencies.

       The filter accepts the following options:

       dry Set dry gain, how much of original signal is kept. Allowed range is
           from 0 to 1.  Default value is 0.7.

       wet Set wet gain, how much of filtered signal is kept. Allowed range is
           from 0 to 1.  Default value is 0.7.

       decay
           Set delay line decay gain value. Allowed range is from 0 to 1.
           Default value is 0.7.

       feedback
           Set delay line feedback gain value. Allowed range is from 0 to 1.
           Default value is 0.9.

       cutoff
           Set cutoff frequency in Hertz. Allowed range is 50 to 900.  Default
           value is 100.

       slope
           Set slope amount for cutoff frequency. Allowed range is 0.0001 to
           1.  Default value is 0.5.

       delay
           Set delay. Allowed range is from 1 to 100.  Default value is 20.

       Commands

       This filter supports the all above options as commands.

   asubcut
       Cut subwoofer frequencies.

       This filter allows to set custom, steeper roll off than highpass
       filter, and thus is able to more attenuate frequency content in stop-
       band.

       The filter accepts the following options:

       cutoff
           Set cutoff frequency in Hertz. Allowed range is 2 to 200.  Default
           value is 20.

       order
           Set filter order. Available values are from 3 to 20.  Default value
           is 10.

       level
           Set input gain level. Allowed range is from 0 to 1. Default value
           is 1.

       Commands

       This filter supports the all above options as commands.

   asupercut
       Cut super frequencies.

       The filter accepts the following options:

       cutoff
           Set cutoff frequency in Hertz. Allowed range is 20000 to 192000.
           Default value is 20000.

       order
           Set filter order. Available values are from 3 to 20.  Default value
           is 10.

       level
           Set input gain level. Allowed range is from 0 to 1. Default value
           is 1.

       Commands

       This filter supports the all above options as commands.

   asuperpass
       Apply high order Butterworth band-pass filter.

       The filter accepts the following options:

       centerf
           Set center frequency in Hertz. Allowed range is 2 to 999999.
           Default value is 1000.

       order
           Set filter order. Available values are from 4 to 20.  Default value
           is 4.

       qfactor
           Set Q-factor. Allowed range is from 0.01 to 100. Default value is
           1.

       level
           Set input gain level. Allowed range is from 0 to 2. Default value
           is 1.

       Commands

       This filter supports the all above options as commands.

   asuperstop
       Apply high order Butterworth band-stop filter.

       The filter accepts the following options:

       centerf
           Set center frequency in Hertz. Allowed range is 2 to 999999.
           Default value is 1000.

       order
           Set filter order. Available values are from 4 to 20.  Default value
           is 4.

       qfactor
           Set Q-factor. Allowed range is from 0.01 to 100. Default value is
           1.

       level
           Set input gain level. Allowed range is from 0 to 2. Default value
           is 1.

       Commands

       This filter supports the all above options as commands.

   atempo
       Adjust audio tempo.

       The filter accepts exactly one parameter, the audio tempo. If not
       specified then the filter will assume nominal 1.0 tempo. Tempo must be
       in the [0.5, 100.0] range.

       Note that tempo greater than 2 will skip some samples rather than blend
       them in.  If for any reason this is a concern it is always possible to
       daisy-chain several instances of atempo to achieve the desired product
       tempo.

       Examples

       o   Slow down audio to 80% tempo:

                   atempo=0.8

       o   To speed up audio to 300% tempo:

                   atempo=3

       o   To speed up audio to 300% tempo by daisy-chaining two atempo
           instances:

                   atempo=sqrt(3),atempo=sqrt(3)

       Commands

       This filter supports the following commands:

       tempo
           Change filter tempo scale factor.  Syntax for the command is :
           "tempo"

   atrim
       Trim the input so that the output contains one continuous subpart of
       the input.

       It accepts the following parameters:

       start
           Timestamp (in seconds) of the start of the section to keep. I.e.
           the audio sample with the timestamp start will be the first sample
           in the output.

       end Specify time of the first audio sample that will be dropped, i.e.
           the audio sample immediately preceding the one with the timestamp
           end will be the last sample in the output.

       start_pts
           Same as start, except this option sets the start timestamp in
           samples instead of seconds.

       end_pts
           Same as end, except this option sets the end timestamp in samples
           instead of seconds.

       duration
           The maximum duration of the output in seconds.

       start_sample
           The number of the first sample that should be output.

       end_sample
           The number of the first sample that should be dropped.

       start, end, and duration are expressed as time duration specifications;
       see the Time duration section in the ffmpeg-utils(1) manual.

       Note that the first two sets of the start/end options and the duration
       option look at the frame timestamp, while the _sample options simply
       count the samples that pass through the filter. So start/end_pts and
       start/end_sample will give different results when the timestamps are
       wrong, inexact or do not start at zero. Also note that this filter does
       not modify the timestamps. If you wish to have the output timestamps
       start at zero, insert the asetpts filter after the atrim filter.

       If multiple start or end options are set, this filter tries to be
       greedy and keep all samples that match at least one of the specified
       constraints. To keep only the part that matches all the constraints at
       once, chain multiple atrim filters.

       The defaults are such that all the input is kept. So it is possible to
       set e.g.  just the end values to keep everything before the specified
       time.

       Examples:

       o   Drop everything except the second minute of input:

                   ffmpeg -i INPUT -af atrim=60:120

       o   Keep only the first 1000 samples:

                   ffmpeg -i INPUT -af atrim=end_sample=1000

   axcorrelate
       Calculate normalized cross-correlation between two input audio streams.

       Resulted samples are always between -1 and 1 inclusive.  If result is 1
       it means two input samples are highly correlated in that selected
       segment.  Result 0 means they are not correlated at all.  If result is
       -1 it means two input samples are out of phase, which means they cancel
       each other.

       The filter accepts the following options:

       size
           Set size of segment over which cross-correlation is calculated.
           Default is 256. Allowed range is from 2 to 131072.

       algo
           Set algorithm for cross-correlation. Can be "slow" or "fast".
           Default is "slow". Fast algorithm assumes mean values over any
           given segment are always zero and thus need much less calculations
           to make.  This is generally not true, but is valid for typical
           audio streams.

       Examples

       o   Calculate correlation between channels in stereo audio stream:

                   ffmpeg -i stereo.wav -af channelsplit,axcorrelate=size=1024:algo=fast correlation.wav

   bandpass
       Apply a two-pole Butterworth band-pass filter with central frequency
       frequency, and (3dB-point) band-width width.  The csg option selects a
       constant skirt gain (peak gain = Q) instead of the default: constant
       0dB peak gain.  The filter roll off at 6dB per octave (20dB per
       decade).

       The filter accepts the following options:

       frequency, f
           Set the filter's central frequency. Default is 3000.

       csg Constant skirt gain if set to 1. Defaults to 0.

       width_type, t
           Set method to specify band-width of filter.

           h   Hz

           q   Q-Factor

           o   octave

           s   slope

           k   kHz

       width, w
           Specify the band-width of a filter in width_type units.

       mix, m
           How much to use filtered signal in output. Default is 1.  Range is
           between 0 and 1.

       channels, c
           Specify which channels to filter, by default all available are
           filtered.

       normalize, n
           Normalize biquad coefficients, by default is disabled.  Enabling it
           will normalize magnitude response at DC to 0dB.

       transform, a
           Set transform type of IIR filter.

           di
           dii
           tdii
           latt
       precision, r
           Set precison of filtering.

           auto
               Pick automatic sample format depending on surround filters.

           s16 Always use signed 16-bit.

           s32 Always use signed 32-bit.

           f32 Always use float 32-bit.

           f64 Always use float 64-bit.

       Commands

       This filter supports the following commands:

       frequency, f
           Change bandpass frequency.  Syntax for the command is : "frequency"

       width_type, t
           Change bandpass width_type.  Syntax for the command is :
           "width_type"

       width, w
           Change bandpass width.  Syntax for the command is : "width"

       mix, m
           Change bandpass mix.  Syntax for the command is : "mix"

   bandreject
       Apply a two-pole Butterworth band-reject filter with central frequency
       frequency, and (3dB-point) band-width width.  The filter roll off at
       6dB per octave (20dB per decade).

       The filter accepts the following options:

       frequency, f
           Set the filter's central frequency. Default is 3000.

       width_type, t
           Set method to specify band-width of filter.

           h   Hz

           q   Q-Factor

           o   octave

           s   slope

           k   kHz

       width, w
           Specify the band-width of a filter in width_type units.

       mix, m
           How much to use filtered signal in output. Default is 1.  Range is
           between 0 and 1.

       channels, c
           Specify which channels to filter, by default all available are
           filtered.

       normalize, n
           Normalize biquad coefficients, by default is disabled.  Enabling it
           will normalize magnitude response at DC to 0dB.

       transform, a
           Set transform type of IIR filter.

           di
           dii
           tdii
           latt
       precision, r
           Set precison of filtering.

           auto
               Pick automatic sample format depending on surround filters.

           s16 Always use signed 16-bit.

           s32 Always use signed 32-bit.

           f32 Always use float 32-bit.

           f64 Always use float 64-bit.

       Commands

       This filter supports the following commands:

       frequency, f
           Change bandreject frequency.  Syntax for the command is :
           "frequency"

       width_type, t
           Change bandreject width_type.  Syntax for the command is :
           "width_type"

       width, w
           Change bandreject width.  Syntax for the command is : "width"

       mix, m
           Change bandreject mix.  Syntax for the command is : "mix"

   bass, lowshelf
       Boost or cut the bass (lower) frequencies of the audio using a two-pole
       shelving filter with a response similar to that of a standard hi-fi's
       tone-controls. This is also known as shelving equalisation (EQ).

       The filter accepts the following options:

       gain, g
           Give the gain at 0 Hz. Its useful range is about -20 (for a large
           cut) to +20 (for a large boost).  Beware of clipping when using a
           positive gain.

       frequency, f
           Set the filter's central frequency and so can be used to extend or
           reduce the frequency range to be boosted or cut.  The default value
           is 100 Hz.

       width_type, t
           Set method to specify band-width of filter.

           h   Hz

           q   Q-Factor

           o   octave

           s   slope

           k   kHz

       width, w
           Determine how steep is the filter's shelf transition.

       poles, p
           Set number of poles. Default is 2.

       mix, m
           How much to use filtered signal in output. Default is 1.  Range is
           between 0 and 1.

       channels, c
           Specify which channels to filter, by default all available are
           filtered.

       normalize, n
           Normalize biquad coefficients, by default is disabled.  Enabling it
           will normalize magnitude response at DC to 0dB.

       transform, a
           Set transform type of IIR filter.

           di
           dii
           tdii
           latt
       precision, r
           Set precison of filtering.

           auto
               Pick automatic sample format depending on surround filters.

           s16 Always use signed 16-bit.

           s32 Always use signed 32-bit.

           f32 Always use float 32-bit.

           f64 Always use float 64-bit.

       Commands

       This filter supports the following commands:

       frequency, f
           Change bass frequency.  Syntax for the command is : "frequency"

       width_type, t
           Change bass width_type.  Syntax for the command is : "width_type"

       width, w
           Change bass width.  Syntax for the command is : "width"

       gain, g
           Change bass gain.  Syntax for the command is : "gain"

       mix, m
           Change bass mix.  Syntax for the command is : "mix"

   biquad
       Apply a biquad IIR filter with the given coefficients.  Where b0, b1,
       b2 and a0, a1, a2 are the numerator and denominator coefficients
       respectively.  and channels, c specify which channels to filter, by
       default all available are filtered.

       Commands

       This filter supports the following commands:

       a0
       a1
       a2
       b0
       b1
       b2  Change biquad parameter.  Syntax for the command is : "value"

       mix, m
           How much to use filtered signal in output. Default is 1.  Range is
           between 0 and 1.

       channels, c
           Specify which channels to filter, by default all available are
           filtered.

       normalize, n
           Normalize biquad coefficients, by default is disabled.  Enabling it
           will normalize magnitude response at DC to 0dB.

       transform, a
           Set transform type of IIR filter.

           di
           dii
           tdii
           latt
       precision, r
           Set precison of filtering.

           auto
               Pick automatic sample format depending on surround filters.

           s16 Always use signed 16-bit.

           s32 Always use signed 32-bit.

           f32 Always use float 32-bit.

           f64 Always use float 64-bit.

   bs2b
       Bauer stereo to binaural transformation, which improves headphone
       listening of stereo audio records.

       To enable compilation of this filter you need to configure FFmpeg with
       "--enable-libbs2b".

       It accepts the following parameters:

       profile
           Pre-defined crossfeed level.

           default
               Default level (fcut=700, feed=50).

           cmoy
               Chu Moy circuit (fcut=700, feed=60).

           jmeier
               Jan Meier circuit (fcut=650, feed=95).

       fcut
           Cut frequency (in Hz).

       feed
           Feed level (in Hz).

   channelmap
       Remap input channels to new locations.

       It accepts the following parameters:

       map Map channels from input to output. The argument is a '|'-separated
           list of mappings, each in the "in_channel-out_channel" or
           in_channel form. in_channel can be either the name of the input
           channel (e.g. FL for front left) or its index in the input channel
           layout.  out_channel is the name of the output channel or its index
           in the output channel layout. If out_channel is not given then it
           is implicitly an index, starting with zero and increasing by one
           for each mapping.

       channel_layout
           The channel layout of the output stream.

       If no mapping is present, the filter will implicitly map input channels
       to output channels, preserving indices.

       Examples

       o   For example, assuming a 5.1+downmix input MOV file,

                   ffmpeg -i in.mov -filter 'channelmap=map=DL-FL|DR-FR' out.wav

           will create an output WAV file tagged as stereo from the downmix
           channels of the input.

       o   To fix a 5.1 WAV improperly encoded in AAC's native channel order

                   ffmpeg -i in.wav -filter 'channelmap=1|2|0|5|3|4:5.1' out.wav

   channelsplit
       Split each channel from an input audio stream into a separate output
       stream.

       It accepts the following parameters:

       channel_layout
           The channel layout of the input stream. The default is "stereo".

       channels
           A channel layout describing the channels to be extracted as
           separate output streams or "all" to extract each input channel as a
           separate stream. The default is "all".

           Choosing channels not present in channel layout in the input will
           result in an error.

       Examples

       o   For example, assuming a stereo input MP3 file,

                   ffmpeg -i in.mp3 -filter_complex channelsplit out.mkv

           will create an output Matroska file with two audio streams, one
           containing only the left channel and the other the right channel.

       o   Split a 5.1 WAV file into per-channel files:

                   ffmpeg -i in.wav -filter_complex
                   'channelsplit=channel_layout=5.1[FL][FR][FC][LFE][SL][SR]'
                   -map '[FL]' front_left.wav -map '[FR]' front_right.wav -map '[FC]'
                   front_center.wav -map '[LFE]' lfe.wav -map '[SL]' side_left.wav -map '[SR]'
                   side_right.wav

       o   Extract only LFE from a 5.1 WAV file:

                   ffmpeg -i in.wav -filter_complex 'channelsplit=channel_layout=5.1:channels=LFE[LFE]'
                   -map '[LFE]' lfe.wav

   chorus
       Add a chorus effect to the audio.

       Can make a single vocal sound like a chorus, but can also be applied to
       instrumentation.

       Chorus resembles an echo effect with a short delay, but whereas with
       echo the delay is constant, with chorus, it is varied using using
       sinusoidal or triangular modulation.  The modulation depth defines the
       range the modulated delay is played before or after the delay. Hence
       the delayed sound will sound slower or faster, that is the delayed
       sound tuned around the original one, like in a chorus where some vocals
       are slightly off key.

       It accepts the following parameters:

       in_gain
           Set input gain. Default is 0.4.

       out_gain
           Set output gain. Default is 0.4.

       delays
           Set delays. A typical delay is around 40ms to 60ms.

       decays
           Set decays.

       speeds
           Set speeds.

       depths
           Set depths.

       Examples

       o   A single delay:

                   chorus=0.7:0.9:55:0.4:0.25:2

       o   Two delays:

                   chorus=0.6:0.9:50|60:0.4|0.32:0.25|0.4:2|1.3

       o   Fuller sounding chorus with three delays:

                   chorus=0.5:0.9:50|60|40:0.4|0.32|0.3:0.25|0.4|0.3:2|2.3|1.3

   compand
       Compress or expand the audio's dynamic range.

       It accepts the following parameters:

       attacks
       decays
           A list of times in seconds for each channel over which the
           instantaneous level of the input signal is averaged to determine
           its volume. attacks refers to increase of volume and decays refers
           to decrease of volume. For most situations, the attack time
           (response to the audio getting louder) should be shorter than the
           decay time, because the human ear is more sensitive to sudden loud
           audio than sudden soft audio. A typical value for attack is 0.3
           seconds and a typical value for decay is 0.8 seconds.  If specified
           number of attacks & decays is lower than number of channels, the
           last set attack/decay will be used for all remaining channels.

       points
           A list of points for the transfer function, specified in dB
           relative to the maximum possible signal amplitude. Each key points
           list must be defined using the following syntax:
           "x0/y0|x1/y1|x2/y2|...." or "x0/y0 x1/y1 x2/y2 ...."

           The input values must be in strictly increasing order but the
           transfer function does not have to be monotonically rising. The
           point "0/0" is assumed but may be overridden (by "0/out-dBn").
           Typical values for the transfer function are "-70/-70|-60/-20|1/0".

       soft-knee
           Set the curve radius in dB for all joints. It defaults to 0.01.

       gain
           Set the additional gain in dB to be applied at all points on the
           transfer function. This allows for easy adjustment of the overall
           gain.  It defaults to 0.

       volume
           Set an initial volume, in dB, to be assumed for each channel when
           filtering starts. This permits the user to supply a nominal level
           initially, so that, for example, a very large gain is not applied
           to initial signal levels before the companding has begun to
           operate. A typical value for audio which is initially quiet is -90
           dB. It defaults to 0.

       delay
           Set a delay, in seconds. The input audio is analyzed immediately,
           but audio is delayed before being fed to the volume adjuster.
           Specifying a delay approximately equal to the attack/decay times
           allows the filter to effectively operate in predictive rather than
           reactive mode. It defaults to 0.

       Examples

       o   Make music with both quiet and loud passages suitable for listening
           to in a noisy environment:

                   compand=.3|.3:1|1:-90/-60|-60/-40|-40/-30|-20/-20:6:0:-90:0.2

           Another example for audio with whisper and explosion parts:

                   compand=0|0:1|1:-90/-900|-70/-70|-30/-9|0/-3:6:0:0:0

       o   A noise gate for when the noise is at a lower level than the
           signal:

                   compand=.1|.1:.2|.2:-900/-900|-50.1/-900|-50/-50:.01:0:-90:.1

       o   Here is another noise gate, this time for when the noise is at a
           higher level than the signal (making it, in some ways, similar to
           squelch):

                   compand=.1|.1:.1|.1:-45.1/-45.1|-45/-900|0/-900:.01:45:-90:.1

       o   2:1 compression starting at -6dB:

                   compand=points=-80/-80|-6/-6|0/-3.8|20/3.5

       o   2:1 compression starting at -9dB:

                   compand=points=-80/-80|-9/-9|0/-5.3|20/2.9

       o   2:1 compression starting at -12dB:

                   compand=points=-80/-80|-12/-12|0/-6.8|20/1.9

       o   2:1 compression starting at -18dB:

                   compand=points=-80/-80|-18/-18|0/-9.8|20/0.7

       o   3:1 compression starting at -15dB:

                   compand=points=-80/-80|-15/-15|0/-10.8|20/-5.2

       o   Compressor/Gate:

                   compand=points=-80/-105|-62/-80|-15.4/-15.4|0/-12|20/-7.6

       o   Expander:

                   compand=attacks=0:points=-80/-169|-54/-80|-49.5/-64.6|-41.1/-41.1|-25.8/-15|-10.8/-4.5|0/0|20/8.3

       o   Hard limiter at -6dB:

                   compand=attacks=0:points=-80/-80|-6/-6|20/-6

       o   Hard limiter at -12dB:

                   compand=attacks=0:points=-80/-80|-12/-12|20/-12

       o   Hard noise gate at -35 dB:

                   compand=attacks=0:points=-80/-115|-35.1/-80|-35/-35|20/20

       o   Soft limiter:

                   compand=attacks=0:points=-80/-80|-12.4/-12.4|-6/-8|0/-6.8|20/-2.8

   compensationdelay
       Compensation Delay Line is a metric based delay to compensate differing
       positions of microphones or speakers.

       For example, you have recorded guitar with two microphones placed in
       different locations. Because the front of sound wave has fixed speed in
       normal conditions, the phasing of microphones can vary and depends on
       their location and interposition. The best sound mix can be achieved
       when these microphones are in phase (synchronized). Note that a
       distance of ~30 cm between microphones makes one microphone capture the
       signal in antiphase to the other microphone. That makes the final mix
       sound moody.  This filter helps to solve phasing problems by adding
       different delays to each microphone track and make them synchronized.

       The best result can be reached when you take one track as base and
       synchronize other tracks one by one with it.  Remember that
       synchronization/delay tolerance depends on sample rate, too.  Higher
       sample rates will give more tolerance.

       The filter accepts the following parameters:

       mm  Set millimeters distance. This is compensation distance for fine
           tuning.  Default is 0.

       cm  Set cm distance. This is compensation distance for tightening
           distance setup.  Default is 0.

       m   Set meters distance. This is compensation distance for hard
           distance setup.  Default is 0.

       dry Set dry amount. Amount of unprocessed (dry) signal.  Default is 0.

       wet Set wet amount. Amount of processed (wet) signal.  Default is 1.

       temp
           Set temperature in degrees Celsius. This is the temperature of the
           environment.  Default is 20.

   crossfeed
       Apply headphone crossfeed filter.

       Crossfeed is the process of blending the left and right channels of
       stereo audio recording.  It is mainly used to reduce extreme stereo
       separation of low frequencies.

       The intent is to produce more speaker like sound to the listener.

       The filter accepts the following options:

       strength
           Set strength of crossfeed. Default is 0.2. Allowed range is from 0
           to 1.  This sets gain of low shelf filter for side part of stereo
           image.  Default is -6dB. Max allowed is -30db when strength is set
           to 1.

       range
           Set soundstage wideness. Default is 0.5. Allowed range is from 0 to
           1.  This sets cut off frequency of low shelf filter. Default is cut
           off near 1550 Hz. With range set to 1 cut off frequency is set to
           2100 Hz.

       slope
           Set curve slope of low shelf filter. Default is 0.5.  Allowed range
           is from 0.01 to 1.

       level_in
           Set input gain. Default is 0.9.

       level_out
           Set output gain. Default is 1.

       Commands

       This filter supports the all above options as commands.

   crystalizer
       Simple algorithm for audio noise sharpening.

       This filter linearly increases differences betweeen each audio sample.

       The filter accepts the following options:

       i   Sets the intensity of effect (default: 2.0). Must be in range
           between -10.0 to 0 (unchanged sound) to 10.0 (maximum effect).  To
           inverse filtering use negative value.

       c   Enable clipping. By default is enabled.

       Commands

       This filter supports the all above options as commands.

   dcshift
       Apply a DC shift to the audio.

       This can be useful to remove a DC offset (caused perhaps by a hardware
       problem in the recording chain) from the audio. The effect of a DC
       offset is reduced headroom and hence volume. The astats filter can be
       used to determine if a signal has a DC offset.

       shift
           Set the DC shift, allowed range is [-1, 1]. It indicates the amount
           to shift the audio.

       limitergain
           Optional. It should have a value much less than 1 (e.g. 0.05 or
           0.02) and is used to prevent clipping.

   deesser
       Apply de-essing to the audio samples.

       i   Set intensity for triggering de-essing. Allowed range is from 0 to
           1.  Default is 0.

       m   Set amount of ducking on treble part of sound. Allowed range is
           from 0 to 1.  Default is 0.5.

       f   How much of original frequency content to keep when de-essing.
           Allowed range is from 0 to 1.  Default is 0.5.

       s   Set the output mode.

           It accepts the following values:

           i   Pass input unchanged.

           o   Pass ess filtered out.

           e   Pass only ess.

               Default value is o.

   drmeter
       Measure audio dynamic range.

       DR values of 14 and higher is found in very dynamic material. DR of 8
       to 13 is found in transition material. And anything less that 8 have
       very poor dynamics and is very compressed.

       The filter accepts the following options:

       length
           Set window length in seconds used to split audio into segments of
           equal length.  Default is 3 seconds.

   dynaudnorm
       Dynamic Audio Normalizer.

       This filter applies a certain amount of gain to the input audio in
       order to bring its peak magnitude to a target level (e.g. 0 dBFS).
       However, in contrast to more "simple" normalization algorithms, the
       Dynamic Audio Normalizer *dynamically* re-adjusts the gain factor to
       the input audio.  This allows for applying extra gain to the "quiet"
       sections of the audio while avoiding distortions or clipping the "loud"
       sections. In other words: The Dynamic Audio Normalizer will "even out"
       the volume of quiet and loud sections, in the sense that the volume of
       each section is brought to the same target level. Note, however, that
       the Dynamic Audio Normalizer achieves this goal *without* applying
       "dynamic range compressing". It will retain 100% of the dynamic range
       *within* each section of the audio file.

       framelen, f
           Set the frame length in milliseconds. In range from 10 to 8000
           milliseconds.  Default is 500 milliseconds.  The Dynamic Audio
           Normalizer processes the input audio in small chunks, referred to
           as frames. This is required, because a peak magnitude has no
           meaning for just a single sample value. Instead, we need to
           determine the peak magnitude for a contiguous sequence of sample
           values. While a "standard" normalizer would simply use the peak
           magnitude of the complete file, the Dynamic Audio Normalizer
           determines the peak magnitude individually for each frame. The
           length of a frame is specified in milliseconds. By default, the
           Dynamic Audio Normalizer uses a frame length of 500 milliseconds,
           which has been found to give good results with most files.  Note
           that the exact frame length, in number of samples, will be
           determined automatically, based on the sampling rate of the
           individual input audio file.

       gausssize, g
           Set the Gaussian filter window size. In range from 3 to 301, must
           be odd number. Default is 31.  Probably the most important
           parameter of the Dynamic Audio Normalizer is the "window size" of
           the Gaussian smoothing filter. The filter's window size is
           specified in frames, centered around the current frame. For the
           sake of simplicity, this must be an odd number. Consequently, the
           default value of 31 takes into account the current frame, as well
           as the 15 preceding frames and the 15 subsequent frames. Using a
           larger window results in a stronger smoothing effect and thus in
           less gain variation, i.e. slower gain adaptation. Conversely, using
           a smaller window results in a weaker smoothing effect and thus in
           more gain variation, i.e. faster gain adaptation.  In other words,
           the more you increase this value, the more the Dynamic Audio
           Normalizer will behave like a "traditional" normalization filter.
           On the contrary, the more you decrease this value, the more the
           Dynamic Audio Normalizer will behave like a dynamic range
           compressor.

       peak, p
           Set the target peak value. This specifies the highest permissible
           magnitude level for the normalized audio input. This filter will
           try to approach the target peak magnitude as closely as possible,
           but at the same time it also makes sure that the normalized signal
           will never exceed the peak magnitude.  A frame's maximum local gain
           factor is imposed directly by the target peak magnitude. The
           default value is 0.95 and thus leaves a headroom of 5%*.  It is not
           recommended to go above this value.

       maxgain, m
           Set the maximum gain factor. In range from 1.0 to 100.0. Default is
           10.0.  The Dynamic Audio Normalizer determines the maximum possible
           (local) gain factor for each input frame, i.e. the maximum gain
           factor that does not result in clipping or distortion. The maximum
           gain factor is determined by the frame's highest magnitude sample.
           However, the Dynamic Audio Normalizer additionally bounds the
           frame's maximum gain factor by a predetermined (global) maximum
           gain factor. This is done in order to avoid excessive gain factors
           in "silent" or almost silent frames. By default, the maximum gain
           factor is 10.0, For most inputs the default value should be
           sufficient and it usually is not recommended to increase this
           value. Though, for input with an extremely low overall volume
           level, it may be necessary to allow even higher gain factors. Note,
           however, that the Dynamic Audio Normalizer does not simply apply a
           "hard" threshold (i.e. cut off values above the threshold).
           Instead, a "sigmoid" threshold function will be applied. This way,
           the gain factors will smoothly approach the threshold value, but
           never exceed that value.

       targetrms, r
           Set the target RMS. In range from 0.0 to 1.0. Default is 0.0 -
           disabled.  By default, the Dynamic Audio Normalizer performs "peak"
           normalization.  This means that the maximum local gain factor for
           each frame is defined (only) by the frame's highest magnitude
           sample. This way, the samples can be amplified as much as possible
           without exceeding the maximum signal level, i.e. without clipping.
           Optionally, however, the Dynamic Audio Normalizer can also take
           into account the frame's root mean square, abbreviated RMS. In
           electrical engineering, the RMS is commonly used to determine the
           power of a time-varying signal. It is therefore considered that the
           RMS is a better approximation of the "perceived loudness" than just
           looking at the signal's peak magnitude. Consequently, by adjusting
           all frames to a constant RMS value, a uniform "perceived loudness"
           can be established. If a target RMS value has been specified, a
           frame's local gain factor is defined as the factor that would
           result in exactly that RMS value.  Note, however, that the maximum
           local gain factor is still restricted by the frame's highest
           magnitude sample, in order to prevent clipping.

       coupling, n
           Enable channels coupling. By default is enabled.  By default, the
           Dynamic Audio Normalizer will amplify all channels by the same
           amount. This means the same gain factor will be applied to all
           channels, i.e.  the maximum possible gain factor is determined by
           the "loudest" channel.  However, in some recordings, it may happen
           that the volume of the different channels is uneven, e.g. one
           channel may be "quieter" than the other one(s).  In this case, this
           option can be used to disable the channel coupling. This way, the
           gain factor will be determined independently for each channel,
           depending only on the individual channel's highest magnitude
           sample. This allows for harmonizing the volume of the different
           channels.

       correctdc, c
           Enable DC bias correction. By default is disabled.  An audio signal
           (in the time domain) is a sequence of sample values.  In the
           Dynamic Audio Normalizer these sample values are represented in the
           -1.0 to 1.0 range, regardless of the original input format.
           Normally, the audio signal, or "waveform", should be centered
           around the zero point.  That means if we calculate the mean value
           of all samples in a file, or in a single frame, then the result
           should be 0.0 or at least very close to that value. If, however,
           there is a significant deviation of the mean value from 0.0, in
           either positive or negative direction, this is referred to as a DC
           bias or DC offset. Since a DC bias is clearly undesirable, the
           Dynamic Audio Normalizer provides optional DC bias correction.
           With DC bias correction enabled, the Dynamic Audio Normalizer will
           determine the mean value, or "DC correction" offset, of each input
           frame and subtract that value from all of the frame's sample values
           which ensures those samples are centered around 0.0 again. Also, in
           order to avoid "gaps" at the frame boundaries, the DC correction
           offset values will be interpolated smoothly between neighbouring
           frames.

       altboundary, b
           Enable alternative boundary mode. By default is disabled.  The
           Dynamic Audio Normalizer takes into account a certain neighbourhood
           around each frame. This includes the preceding frames as well as
           the subsequent frames. However, for the "boundary" frames, located
           at the very beginning and at the very end of the audio file, not
           all neighbouring frames are available. In particular, for the first
           few frames in the audio file, the preceding frames are not known.
           And, similarly, for the last few frames in the audio file, the
           subsequent frames are not known. Thus, the question arises which
           gain factors should be assumed for the missing frames in the
           "boundary" region. The Dynamic Audio Normalizer implements two
           modes to deal with this situation. The default boundary mode
           assumes a gain factor of exactly 1.0 for the missing frames,
           resulting in a smooth "fade in" and "fade out" at the beginning and
           at the end of the input, respectively.

       compress, s
           Set the compress factor. In range from 0.0 to 30.0. Default is 0.0.
           By default, the Dynamic Audio Normalizer does not apply
           "traditional" compression. This means that signal peaks will not be
           pruned and thus the full dynamic range will be retained within each
           local neighbourhood. However, in some cases it may be desirable to
           combine the Dynamic Audio Normalizer's normalization algorithm with
           a more "traditional" compression.  For this purpose, the Dynamic
           Audio Normalizer provides an optional compression (thresholding)
           function. If (and only if) the compression feature is enabled, all
           input frames will be processed by a soft knee thresholding function
           prior to the actual normalization process. Put simply, the
           thresholding function is going to prune all samples whose magnitude
           exceeds a certain threshold value.  However, the Dynamic Audio
           Normalizer does not simply apply a fixed threshold value. Instead,
           the threshold value will be adjusted for each individual frame.  In
           general, smaller parameters result in stronger compression, and
           vice versa.  Values below 3.0 are not recommended, because audible
           distortion may appear.

       threshold, t
           Set the target threshold value. This specifies the lowest
           permissible magnitude level for the audio input which will be
           normalized.  If input frame volume is above this value frame will
           be normalized.  Otherwise frame may not be normalized at all. The
           default value is set to 0, which means all input frames will be
           normalized.  This option is mostly useful if digital noise is not
           wanted to be amplified.

       Commands

       This filter supports the all above options as commands.

   earwax
       Make audio easier to listen to on headphones.

       This filter adds `cues' to 44.1kHz stereo (i.e. audio CD format) audio
       so that when listened to on headphones the stereo image is moved from
       inside your head (standard for headphones) to outside and in front of
       the listener (standard for speakers).

       Ported from SoX.

   equalizer
       Apply a two-pole peaking equalisation (EQ) filter. With this filter,
       the signal-level at and around a selected frequency can be increased or
       decreased, whilst (unlike bandpass and bandreject filters) that at all
       other frequencies is unchanged.

       In order to produce complex equalisation curves, this filter can be
       given several times, each with a different central frequency.

       The filter accepts the following options:

       frequency, f
           Set the filter's central frequency in Hz.

       width_type, t
           Set method to specify band-width of filter.

           h   Hz

           q   Q-Factor

           o   octave

           s   slope

           k   kHz

       width, w
           Specify the band-width of a filter in width_type units.

       gain, g
           Set the required gain or attenuation in dB.  Beware of clipping
           when using a positive gain.

       mix, m
           How much to use filtered signal in output. Default is 1.  Range is
           between 0 and 1.

       channels, c
           Specify which channels to filter, by default all available are
           filtered.

       normalize, n
           Normalize biquad coefficients, by default is disabled.  Enabling it
           will normalize magnitude response at DC to 0dB.

       transform, a
           Set transform type of IIR filter.

           di
           dii
           tdii
           latt
       precision, r
           Set precison of filtering.

           auto
               Pick automatic sample format depending on surround filters.

           s16 Always use signed 16-bit.

           s32 Always use signed 32-bit.

           f32 Always use float 32-bit.

           f64 Always use float 64-bit.

       Examples

       o   Attenuate 10 dB at 1000 Hz, with a bandwidth of 200 Hz:

                   equalizer=f=1000:t=h:width=200:g=-10

       o   Apply 2 dB gain at 1000 Hz with Q 1 and attenuate 5 dB at 100 Hz
           with Q 2:

                   equalizer=f=1000:t=q:w=1:g=2,equalizer=f=100:t=q:w=2:g=-5

       Commands

       This filter supports the following commands:

       frequency, f
           Change equalizer frequency.  Syntax for the command is :
           "frequency"

       width_type, t
           Change equalizer width_type.  Syntax for the command is :
           "width_type"

       width, w
           Change equalizer width.  Syntax for the command is : "width"

       gain, g
           Change equalizer gain.  Syntax for the command is : "gain"

       mix, m
           Change equalizer mix.  Syntax for the command is : "mix"

   extrastereo
       Linearly increases the difference between left and right channels which
       adds some sort of "live" effect to playback.

       The filter accepts the following options:

       m   Sets the difference coefficient (default: 2.5). 0.0 means mono
           sound (average of both channels), with 1.0 sound will be unchanged,
           with -1.0 left and right channels will be swapped.

       c   Enable clipping. By default is enabled.

       Commands

       This filter supports the all above options as commands.

   firequalizer
       Apply FIR Equalization using arbitrary frequency response.

       The filter accepts the following option:

       gain
           Set gain curve equation (in dB). The expression can contain
           variables:

           f   the evaluated frequency

           sr  sample rate

           ch  channel number, set to 0 when multichannels evaluation is
               disabled

           chid
               channel id, see libavutil/channel_layout.h, set to the first
               channel id when multichannels evaluation is disabled

           chs number of channels

           chlayout
               channel_layout, see libavutil/channel_layout.h

           and functions:

           gain_interpolate(f)
               interpolate gain on frequency f based on gain_entry

           cubic_interpolate(f)
               same as gain_interpolate, but smoother

           This option is also available as command. Default is
           gain_interpolate(f).

       gain_entry
           Set gain entry for gain_interpolate function. The expression can
           contain functions:

           entry(f, g)
               store gain entry at frequency f with value g

           This option is also available as command.

       delay
           Set filter delay in seconds. Higher value means more accurate.
           Default is 0.01.

       accuracy
           Set filter accuracy in Hz. Lower value means more accurate.
           Default is 5.

       wfunc
           Set window function. Acceptable values are:

           rectangular
               rectangular window, useful when gain curve is already smooth

           hann
               hann window (default)

           hamming
               hamming window

           blackman
               blackman window

           nuttall3
               3-terms continuous 1st derivative nuttall window

           mnuttall3
               minimum 3-terms discontinuous nuttall window

           nuttall
               4-terms continuous 1st derivative nuttall window

           bnuttall
               minimum 4-terms discontinuous nuttall (blackman-nuttall) window

           bharris
               blackman-harris window

           tukey
               tukey window

       fixed
           If enabled, use fixed number of audio samples. This improves speed
           when filtering with large delay. Default is disabled.

       multi
           Enable multichannels evaluation on gain. Default is disabled.

       zero_phase
           Enable zero phase mode by subtracting timestamp to compensate
           delay.  Default is disabled.

       scale
           Set scale used by gain. Acceptable values are:

           linlin
               linear frequency, linear gain

           linlog
               linear frequency, logarithmic (in dB) gain (default)

           loglin
               logarithmic (in octave scale where 20 Hz is 0) frequency,
               linear gain

           loglog
               logarithmic frequency, logarithmic gain

       dumpfile
           Set file for dumping, suitable for gnuplot.

       dumpscale
           Set scale for dumpfile. Acceptable values are same with scale
           option.  Default is linlog.

       fft2
           Enable 2-channel convolution using complex FFT. This improves speed
           significantly.  Default is disabled.

       min_phase
           Enable minimum phase impulse response. Default is disabled.

       Examples

       o   lowpass at 1000 Hz:

                   firequalizer=gain='if(lt(f,1000), 0, -INF)'

       o   lowpass at 1000 Hz with gain_entry:

                   firequalizer=gain_entry='entry(1000,0); entry(1001, -INF)'

       o   custom equalization:

                   firequalizer=gain_entry='entry(100,0); entry(400, -4); entry(1000, -6); entry(2000, 0)'

       o   higher delay with zero phase to compensate delay:

                   firequalizer=delay=0.1:fixed=on:zero_phase=on

       o   lowpass on left channel, highpass on right channel:

                   firequalizer=gain='if(eq(chid,1), gain_interpolate(f), if(eq(chid,2), gain_interpolate(1e6+f), 0))'
                   :gain_entry='entry(1000, 0); entry(1001,-INF); entry(1e6+1000,0)':multi=on

   flanger
       Apply a flanging effect to the audio.

       The filter accepts the following options:

       delay
           Set base delay in milliseconds. Range from 0 to 30. Default value
           is 0.

       depth
           Set added sweep delay in milliseconds. Range from 0 to 10. Default
           value is 2.

       regen
           Set percentage regeneration (delayed signal feedback). Range from
           -95 to 95.  Default value is 0.

       width
           Set percentage of delayed signal mixed with original. Range from 0
           to 100.  Default value is 71.

       speed
           Set sweeps per second (Hz). Range from 0.1 to 10. Default value is
           0.5.

       shape
           Set swept wave shape, can be triangular or sinusoidal.  Default
           value is sinusoidal.

       phase
           Set swept wave percentage-shift for multi channel. Range from 0 to
           100.  Default value is 25.

       interp
           Set delay-line interpolation, linear or quadratic.  Default is
           linear.

   haas
       Apply Haas effect to audio.

       Note that this makes most sense to apply on mono signals.  With this
       filter applied to mono signals it give some directionality and
       stretches its stereo image.

       The filter accepts the following options:

       level_in
           Set input level. By default is 1, or 0dB

       level_out
           Set output level. By default is 1, or 0dB.

       side_gain
           Set gain applied to side part of signal. By default is 1.

       middle_source
           Set kind of middle source. Can be one of the following:

           left
               Pick left channel.

           right
               Pick right channel.

           mid Pick middle part signal of stereo image.

           side
               Pick side part signal of stereo image.

       middle_phase
           Change middle phase. By default is disabled.

       left_delay
           Set left channel delay. By default is 2.05 milliseconds.

       left_balance
           Set left channel balance. By default is -1.

       left_gain
           Set left channel gain. By default is 1.

       left_phase
           Change left phase. By default is disabled.

       right_delay
           Set right channel delay. By defaults is 2.12 milliseconds.

       right_balance
           Set right channel balance. By default is 1.

       right_gain
           Set right channel gain. By default is 1.

       right_phase
           Change right phase. By default is enabled.

   hdcd
       Decodes High Definition Compatible Digital (HDCD) data. A 16-bit PCM
       stream with embedded HDCD codes is expanded into a 20-bit PCM stream.

       The filter supports the Peak Extend and Low-level Gain Adjustment
       features of HDCD, and detects the Transient Filter flag.

               ffmpeg -i HDCD16.flac -af hdcd OUT24.flac

       When using the filter with wav, note the default encoding for wav is
       16-bit, so the resulting 20-bit stream will be truncated back to
       16-bit. Use something like -acodec pcm_s24le after the filter to get
       24-bit PCM output.

               ffmpeg -i HDCD16.wav -af hdcd OUT16.wav
               ffmpeg -i HDCD16.wav -af hdcd -c:a pcm_s24le OUT24.wav

       The filter accepts the following options:

       disable_autoconvert
           Disable any automatic format conversion or resampling in the filter
           graph.

       process_stereo
           Process the stereo channels together. If target_gain does not match
           between channels, consider it invalid and use the last valid
           target_gain.

       cdt_ms
           Set the code detect timer period in ms.

       force_pe
           Always extend peaks above -3dBFS even if PE isn't signaled.

       analyze_mode
           Replace audio with a solid tone and adjust the amplitude to signal
           some specific aspect of the decoding process. The output file can
           be loaded in an audio editor alongside the original to aid
           analysis.

           "analyze_mode=pe:force_pe=true" can be used to see all samples
           above the PE level.

           Modes are:

           0, off
               Disabled

           1, lle
               Gain adjustment level at each sample

           2, pe
               Samples where peak extend occurs

           3, cdt
               Samples where the code detect timer is active

           4, tgm
               Samples where the target gain does not match between channels

   headphone
       Apply head-related transfer functions (HRTFs) to create virtual
       loudspeakers around the user for binaural listening via headphones.
       The HRIRs are provided via additional streams, for each channel one
       stereo input stream is needed.

       The filter accepts the following options:

       map Set mapping of input streams for convolution.  The argument is a
           '|'-separated list of channel names in order as they are given as
           additional stream inputs for filter.  This also specify number of
           input streams. Number of input streams must be not less than number
           of channels in first stream plus one.

       gain
           Set gain applied to audio. Value is in dB. Default is 0.

       type
           Set processing type. Can be time or freq. time is processing audio
           in time domain which is slow.  freq is processing audio in
           frequency domain which is fast.  Default is freq.

       lfe Set custom gain for LFE channels. Value is in dB. Default is 0.

       size
           Set size of frame in number of samples which will be processed at
           once.  Default value is 1024. Allowed range is from 1024 to 96000.

       hrir
           Set format of hrir stream.  Default value is stereo. Alternative
           value is multich.  If value is set to stereo, number of additional
           streams should be greater or equal to number of input channels in
           first input stream.  Also each additional stream should have stereo
           number of channels.  If value is set to multich, number of
           additional streams should be exactly one. Also number of input
           channels of additional stream should be equal or greater than twice
           number of channels of first input stream.

       Examples

       o   Full example using wav files as coefficients with amovie filters
           for 7.1 downmix, each amovie filter use stereo file with IR
           coefficients as input.  The files give coefficients for each
           position of virtual loudspeaker:

                   ffmpeg -i input.wav
                   -filter_complex "amovie=azi_270_ele_0_DFC.wav[sr];amovie=azi_90_ele_0_DFC.wav[sl];amovie=azi_225_ele_0_DFC.wav[br];amovie=azi_135_ele_0_DFC.wav[bl];amovie=azi_0_ele_0_DFC.wav,asplit[fc][lfe];amovie=azi_35_ele_0_DFC.wav[fl];amovie=azi_325_ele_0_DFC.wav[fr];[0:a][fl][fr][fc][lfe][bl][br][sl][sr]headphone=FL|FR|FC|LFE|BL|BR|SL|SR"
                   output.wav

       o   Full example using wav files as coefficients with amovie filters
           for 7.1 downmix, but now in multich hrir format.

                   ffmpeg -i input.wav -filter_complex "amovie=minp.wav[hrirs];[0:a][hrirs]headphone=map=FL|FR|FC|LFE|BL|BR|SL|SR:hrir=multich"
                   output.wav

   highpass
       Apply a high-pass filter with 3dB point frequency.  The filter can be
       either single-pole, or double-pole (the default).  The filter roll off
       at 6dB per pole per octave (20dB per pole per decade).

       The filter accepts the following options:

       frequency, f
           Set frequency in Hz. Default is 3000.

       poles, p
           Set number of poles. Default is 2.

       width_type, t
           Set method to specify band-width of filter.

           h   Hz

           q   Q-Factor

           o   octave

           s   slope

           k   kHz

       width, w
           Specify the band-width of a filter in width_type units.  Applies
           only to double-pole filter.  The default is 0.707q and gives a
           Butterworth response.

       mix, m
           How much to use filtered signal in output. Default is 1.  Range is
           between 0 and 1.

       channels, c
           Specify which channels to filter, by default all available are
           filtered.

       normalize, n
           Normalize biquad coefficients, by default is disabled.  Enabling it
           will normalize magnitude response at DC to 0dB.

       transform, a
           Set transform type of IIR filter.

           di
           dii
           tdii
           latt
       precision, r
           Set precison of filtering.

           auto
               Pick automatic sample format depending on surround filters.

           s16 Always use signed 16-bit.

           s32 Always use signed 32-bit.

           f32 Always use float 32-bit.

           f64 Always use float 64-bit.

       Commands

       This filter supports the following commands:

       frequency, f
           Change highpass frequency.  Syntax for the command is : "frequency"

       width_type, t
           Change highpass width_type.  Syntax for the command is :
           "width_type"

       width, w
           Change highpass width.  Syntax for the command is : "width"

       mix, m
           Change highpass mix.  Syntax for the command is : "mix"

   join
       Join multiple input streams into one multi-channel stream.

       It accepts the following parameters:

       inputs
           The number of input streams. It defaults to 2.

       channel_layout
           The desired output channel layout. It defaults to stereo.

       map Map channels from inputs to output. The argument is a '|'-separated
           list of mappings, each in the "input_idx.in_channel-out_channel"
           form. input_idx is the 0-based index of the input stream.
           in_channel can be either the name of the input channel (e.g. FL for
           front left) or its index in the specified input stream. out_channel
           is the name of the output channel.

       The filter will attempt to guess the mappings when they are not
       specified explicitly. It does so by first trying to find an unused
       matching input channel and if that fails it picks the first unused
       input channel.

       Join 3 inputs (with properly set channel layouts):

               ffmpeg -i INPUT1 -i INPUT2 -i INPUT3 -filter_complex join=inputs=3 OUTPUT

       Build a 5.1 output from 6 single-channel streams:

               ffmpeg -i fl -i fr -i fc -i sl -i sr -i lfe -filter_complex
               'join=inputs=6:channel_layout=5.1:map=0.0-FL|1.0-FR|2.0-FC|3.0-SL|4.0-SR|5.0-LFE'
               out

   ladspa
       Load a LADSPA (Linux Audio Developer's Simple Plugin API) plugin.

       To enable compilation of this filter you need to configure FFmpeg with
       "--enable-ladspa".

       file, f
           Specifies the name of LADSPA plugin library to load. If the
           environment variable LADSPA_PATH is defined, the LADSPA plugin is
           searched in each one of the directories specified by the colon
           separated list in LADSPA_PATH, otherwise in the standard LADSPA
           paths, which are in this order: HOME/.ladspa/lib/,
           /usr/local/lib/ladspa/, /usr/lib/ladspa/.

       plugin, p
           Specifies the plugin within the library. Some libraries contain
           only one plugin, but others contain many of them. If this is not
           set filter will list all available plugins within the specified
           library.

       controls, c
           Set the '|' separated list of controls which are zero or more
           floating point values that determine the behavior of the loaded
           plugin (for example delay, threshold or gain).  Controls need to be
           defined using the following syntax:
           c0=value0|c1=value1|c2=value2|..., where valuei is the value set on
           the i-th control.  Alternatively they can be also defined using the
           following syntax: value0|value1|value2|..., where valuei is the
           value set on the i-th control.  If controls is set to "help", all
           available controls and their valid ranges are printed.

       sample_rate, s
           Specify the sample rate, default to 44100. Only used if plugin have
           zero inputs.

       nb_samples, n
           Set the number of samples per channel per each output frame,
           default is 1024. Only used if plugin have zero inputs.

       duration, d
           Set the minimum duration of the sourced audio. See the Time
           duration section in the ffmpeg-utils(1) manual for the accepted
           syntax.  Note that the resulting duration may be greater than the
           specified duration, as the generated audio is always cut at the end
           of a complete frame.  If not specified, or the expressed duration
           is negative, the audio is supposed to be generated forever.  Only
           used if plugin have zero inputs.

       latency, l
           Enable latency compensation, by default is disabled.  Only used if
           plugin have inputs.

       Examples

       o   List all available plugins within amp (LADSPA example plugin)
           library:

                   ladspa=file=amp

       o   List all available controls and their valid ranges for "vcf_notch"
           plugin from "VCF" library:

                   ladspa=f=vcf:p=vcf_notch:c=help

       o   Simulate low quality audio equipment using "Computer Music Toolkit"
           (CMT) plugin library:

                   ladspa=file=cmt:plugin=lofi:controls=c0=22|c1=12|c2=12

       o   Add reverberation to the audio using TAP-plugins (Tom's Audio
           Processing plugins):

                   ladspa=file=tap_reverb:tap_reverb

       o   Generate white noise, with 0.2 amplitude:

                   ladspa=file=cmt:noise_source_white:c=c0=.2

       o   Generate 20 bpm clicks using plugin "C* Click - Metronome" from the
           "C* Audio Plugin Suite" (CAPS) library:

                   ladspa=file=caps:Click:c=c1=20'

       o   Apply "C* Eq10X2 - Stereo 10-band equaliser" effect:

                   ladspa=caps:Eq10X2:c=c0=-48|c9=-24|c3=12|c4=2

       o   Increase volume by 20dB using fast lookahead limiter from Steve
           Harris "SWH Plugins" collection:

                   ladspa=fast_lookahead_limiter_1913:fastLookaheadLimiter:20|0|2

       o   Attenuate low frequencies using Multiband EQ from Steve Harris "SWH
           Plugins" collection:

                   ladspa=mbeq_1197:mbeq:-24|-24|-24|0|0|0|0|0|0|0|0|0|0|0|0

       o   Reduce stereo image using "Narrower" from the "C* Audio Plugin
           Suite" (CAPS) library:

                   ladspa=caps:Narrower

       o   Another white noise, now using "C* Audio Plugin Suite" (CAPS)
           library:

                   ladspa=caps:White:.2

       o   Some fractal noise, using "C* Audio Plugin Suite" (CAPS) library:

                   ladspa=caps:Fractal:c=c1=1

       o   Dynamic volume normalization using "VLevel" plugin:

                   ladspa=vlevel-ladspa:vlevel_mono

       Commands

       This filter supports the following commands:

       cN  Modify the N-th control value.

           If the specified value is not valid, it is ignored and prior one is
           kept.

   loudnorm
       EBU R128 loudness normalization. Includes both dynamic and linear
       normalization modes.  Support for both single pass (livestreams, files)
       and double pass (files) modes.  This algorithm can target IL, LRA, and
       maximum true peak. In dynamic mode, to accurately detect true peaks,
       the audio stream will be upsampled to 192 kHz.  Use the "-ar" option or
       "aresample" filter to explicitly set an output sample rate.

       The filter accepts the following options:

       I, i
           Set integrated loudness target.  Range is -70.0 - -5.0. Default
           value is -24.0.

       LRA, lra
           Set loudness range target.  Range is 1.0 - 20.0. Default value is
           7.0.

       TP, tp
           Set maximum true peak.  Range is -9.0 - +0.0. Default value is
           -2.0.

       measured_I, measured_i
           Measured IL of input file.  Range is -99.0 - +0.0.

       measured_LRA, measured_lra
           Measured LRA of input file.  Range is  0.0 - 99.0.

       measured_TP, measured_tp
           Measured true peak of input file.  Range is  -99.0 - +99.0.

       measured_thresh
           Measured threshold of input file.  Range is -99.0 - +0.0.

       offset
           Set offset gain. Gain is applied before the true-peak limiter.
           Range is  -99.0 - +99.0. Default is +0.0.

       linear
           Normalize by linearly scaling the source audio.  "measured_I",
           "measured_LRA", "measured_TP", and "measured_thresh" must all be
           specified. Target LRA shouldn't be lower than source LRA and the
           change in integrated loudness shouldn't result in a true peak which
           exceeds the target TP. If any of these conditions aren't met,
           normalization mode will revert to dynamic.  Options are "true" or
           "false". Default is "true".

       dual_mono
           Treat mono input files as "dual-mono". If a mono file is intended
           for playback on a stereo system, its EBU R128 measurement will be
           perceptually incorrect.  If set to "true", this option will
           compensate for this effect.  Multi-channel input files are not
           affected by this option.  Options are true or false. Default is
           false.

       print_format
           Set print format for stats. Options are summary, json, or none.
           Default value is none.

   lowpass
       Apply a low-pass filter with 3dB point frequency.  The filter can be
       either single-pole or double-pole (the default).  The filter roll off
       at 6dB per pole per octave (20dB per pole per decade).

       The filter accepts the following options:

       frequency, f
           Set frequency in Hz. Default is 500.

       poles, p
           Set number of poles. Default is 2.

       width_type, t
           Set method to specify band-width of filter.

           h   Hz

           q   Q-Factor

           o   octave

           s   slope

           k   kHz

       width, w
           Specify the band-width of a filter in width_type units.  Applies
           only to double-pole filter.  The default is 0.707q and gives a
           Butterworth response.

       mix, m
           How much to use filtered signal in output. Default is 1.  Range is
           between 0 and 1.

       channels, c
           Specify which channels to filter, by default all available are
           filtered.

       normalize, n
           Normalize biquad coefficients, by default is disabled.  Enabling it
           will normalize magnitude response at DC to 0dB.

       transform, a
           Set transform type of IIR filter.

           di
           dii
           tdii
           latt
       precision, r
           Set precison of filtering.

           auto
               Pick automatic sample format depending on surround filters.

           s16 Always use signed 16-bit.

           s32 Always use signed 32-bit.

           f32 Always use float 32-bit.

           f64 Always use float 64-bit.

       Examples

       o   Lowpass only LFE channel, it LFE is not present it does nothing:

                   lowpass=c=LFE

       Commands

       This filter supports the following commands:

       frequency, f
           Change lowpass frequency.  Syntax for the command is : "frequency"

       width_type, t
           Change lowpass width_type.  Syntax for the command is :
           "width_type"

       width, w
           Change lowpass width.  Syntax for the command is : "width"

       mix, m
           Change lowpass mix.  Syntax for the command is : "mix"

   lv2
       Load a LV2 (LADSPA Version 2) plugin.

       To enable compilation of this filter you need to configure FFmpeg with
       "--enable-lv2".

       plugin, p
           Specifies the plugin URI. You may need to escape ':'.

       controls, c
           Set the '|' separated list of controls which are zero or more
           floating point values that determine the behavior of the loaded
           plugin (for example delay, threshold or gain).  If controls is set
           to "help", all available controls and their valid ranges are
           printed.

       sample_rate, s
           Specify the sample rate, default to 44100. Only used if plugin have
           zero inputs.

       nb_samples, n
           Set the number of samples per channel per each output frame,
           default is 1024. Only used if plugin have zero inputs.

       duration, d
           Set the minimum duration of the sourced audio. See the Time
           duration section in the ffmpeg-utils(1) manual for the accepted
           syntax.  Note that the resulting duration may be greater than the
           specified duration, as the generated audio is always cut at the end
           of a complete frame.  If not specified, or the expressed duration
           is negative, the audio is supposed to be generated forever.  Only
           used if plugin have zero inputs.

       Examples

       o   Apply bass enhancer plugin from Calf:

                   lv2=p=http\\\\://calf.sourceforge.net/plugins/BassEnhancer:c=amount=2

       o   Apply vinyl plugin from Calf:

                   lv2=p=http\\\\://calf.sourceforge.net/plugins/Vinyl:c=drone=0.2|aging=0.5

       o   Apply bit crusher plugin from ArtyFX:

                   lv2=p=http\\\\://www.openavproductions.com/artyfx#bitta:c=crush=0.3

   mcompand
       Multiband Compress or expand the audio's dynamic range.

       The input audio is divided into bands using 4th order Linkwitz-Riley
       IIRs.  This is akin to the crossover of a loudspeaker, and results in
       flat frequency response when absent compander action.

       It accepts the following parameters:

       args
           This option syntax is: attack,decay,[attack,decay..] soft-knee
           points crossover_frequency [delay [initial_volume [gain]]] |
           attack,decay ...  For explanation of each item refer to compand
           filter documentation.

   pan
       Mix channels with specific gain levels. The filter accepts the output
       channel layout followed by a set of channels definitions.

       This filter is also designed to efficiently remap the channels of an
       audio stream.

       The filter accepts parameters of the form: "l|outdef|outdef|..."

       l   output channel layout or number of channels

       outdef
           output channel specification, of the form:
           "out_name=[gain*]in_name[(+-)[gain*]in_name...]"

       out_name
           output channel to define, either a channel name (FL, FR, etc.) or a
           channel number (c0, c1, etc.)

       gain
           multiplicative coefficient for the channel, 1 leaving the volume
           unchanged

       in_name
           input channel to use, see out_name for details; it is not possible
           to mix named and numbered input channels

       If the `=' in a channel specification is replaced by `<', then the
       gains for that specification will be renormalized so that the total is
       1, thus avoiding clipping noise.

       Mixing examples

       For example, if you want to down-mix from stereo to mono, but with a
       bigger factor for the left channel:

               pan=1c|c0=0.9*c0+0.1*c1

       A customized down-mix to stereo that works automatically for 3-, 4-, 5-
       and 7-channels surround:

               pan=stereo| FL < FL + 0.5*FC + 0.6*BL + 0.6*SL | FR < FR + 0.5*FC + 0.6*BR + 0.6*SR

       Note that ffmpeg integrates a default down-mix (and up-mix) system that
       should be preferred (see "-ac" option) unless you have very specific
       needs.

       Remapping examples

       The channel remapping will be effective if, and only if:

       *<gain coefficients are zeroes or ones,>
       *<only one input per channel output,>

       If all these conditions are satisfied, the filter will notify the user
       ("Pure channel mapping detected"), and use an optimized and lossless
       method to do the remapping.

       For example, if you have a 5.1 source and want a stereo audio stream by
       dropping the extra channels:

               pan="stereo| c0=FL | c1=FR"

       Given the same source, you can also switch front left and front right
       channels and keep the input channel layout:

               pan="5.1| c0=c1 | c1=c0 | c2=c2 | c3=c3 | c4=c4 | c5=c5"

       If the input is a stereo audio stream, you can mute the front left
       channel (and still keep the stereo channel layout) with:

               pan="stereo|c1=c1"

       Still with a stereo audio stream input, you can copy the right channel
       in both front left and right:

               pan="stereo| c0=FR | c1=FR"

   replaygain
       ReplayGain scanner filter. This filter takes an audio stream as an
       input and outputs it unchanged.  At end of filtering it displays
       "track_gain" and "track_peak".

   resample
       Convert the audio sample format, sample rate and channel layout. It is
       not meant to be used directly.

   rubberband
       Apply time-stretching and pitch-shifting with librubberband.

       To enable compilation of this filter, you need to configure FFmpeg with
       "--enable-librubberband".

       The filter accepts the following options:

       tempo
           Set tempo scale factor.

       pitch
           Set pitch scale factor.

       transients
           Set transients detector.  Possible values are:

           crisp
           mixed
           smooth
       detector
           Set detector.  Possible values are:

           compound
           percussive
           soft
       phase
           Set phase.  Possible values are:

           laminar
           independent
       window
           Set processing window size.  Possible values are:

           standard
           short
           long
       smoothing
           Set smoothing.  Possible values are:

           off
           on
       formant
           Enable formant preservation when shift pitching.  Possible values
           are:

           shifted
           preserved
       pitchq
           Set pitch quality.  Possible values are:

           quality
           speed
           consistency
       channels
           Set channels.  Possible values are:

           apart
           together

       Commands

       This filter supports the following commands:

       tempo
           Change filter tempo scale factor.  Syntax for the command is :
           "tempo"

       pitch
           Change filter pitch scale factor.  Syntax for the command is :
           "pitch"

   sidechaincompress
       This filter acts like normal compressor but has the ability to compress
       detected signal using second input signal.  It needs two input streams
       and returns one output stream.  First input stream will be processed
       depending on second stream signal.  The filtered signal then can be
       filtered with other filters in later stages of processing. See pan and
       amerge filter.

       The filter accepts the following options:

       level_in
           Set input gain. Default is 1. Range is between 0.015625 and 64.

       mode
           Set mode of compressor operation. Can be "upward" or "downward".
           Default is "downward".

       threshold
           If a signal of second stream raises above this level it will affect
           the gain reduction of first stream.  By default is 0.125. Range is
           between 0.00097563 and 1.

       ratio
           Set a ratio about which the signal is reduced. 1:2 means that if
           the level raised 4dB above the threshold, it will be only 2dB above
           after the reduction.  Default is 2. Range is between 1 and 20.

       attack
           Amount of milliseconds the signal has to rise above the threshold
           before gain reduction starts. Default is 20. Range is between 0.01
           and 2000.

       release
           Amount of milliseconds the signal has to fall below the threshold
           before reduction is decreased again. Default is 250. Range is
           between 0.01 and 9000.

       makeup
           Set the amount by how much signal will be amplified after
           processing.  Default is 1. Range is from 1 to 64.

       knee
           Curve the sharp knee around the threshold to enter gain reduction
           more softly.  Default is 2.82843. Range is between 1 and 8.

       link
           Choose if the "average" level between all channels of side-chain
           stream or the louder("maximum") channel of side-chain stream
           affects the reduction. Default is "average".

       detection
           Should the exact signal be taken in case of "peak" or an RMS one in
           case of "rms". Default is "rms" which is mainly smoother.

       level_sc
           Set sidechain gain. Default is 1. Range is between 0.015625 and 64.

       mix How much to use compressed signal in output. Default is 1.  Range
           is between 0 and 1.

       Commands

       This filter supports the all above options as commands.

       Examples

       o   Full ffmpeg example taking 2 audio inputs, 1st input to be
           compressed depending on the signal of 2nd input and later
           compressed signal to be merged with 2nd input:

                   ffmpeg -i main.flac -i sidechain.flac -filter_complex "[1:a]asplit=2[sc][mix];[0:a][sc]sidechaincompress[compr];[compr][mix]amerge"

   sidechaingate
       A sidechain gate acts like a normal (wideband) gate but has the ability
       to filter the detected signal before sending it to the gain reduction
       stage.  Normally a gate uses the full range signal to detect a level
       above the threshold.  For example: If you cut all lower frequencies
       from your sidechain signal the gate will decrease the volume of your
       track only if not enough highs appear. With this technique you are able
       to reduce the resonation of a natural drum or remove "rumbling" of
       muted strokes from a heavily distorted guitar.  It needs two input
       streams and returns one output stream.  First input stream will be
       processed depending on second stream signal.

       The filter accepts the following options:

       level_in
           Set input level before filtering.  Default is 1. Allowed range is
           from 0.015625 to 64.

       mode
           Set the mode of operation. Can be "upward" or "downward".  Default
           is "downward". If set to "upward" mode, higher parts of signal will
           be amplified, expanding dynamic range in upward direction.
           Otherwise, in case of "downward" lower parts of signal will be
           reduced.

       range
           Set the level of gain reduction when the signal is below the
           threshold.  Default is 0.06125. Allowed range is from 0 to 1.
           Setting this to 0 disables reduction and then filter behaves like
           expander.

       threshold
           If a signal rises above this level the gain reduction is released.
           Default is 0.125. Allowed range is from 0 to 1.

       ratio
           Set a ratio about which the signal is reduced.  Default is 2.
           Allowed range is from 1 to 9000.

       attack
           Amount of milliseconds the signal has to rise above the threshold
           before gain reduction stops.  Default is 20 milliseconds. Allowed
           range is from 0.01 to 9000.

       release
           Amount of milliseconds the signal has to fall below the threshold
           before the reduction is increased again. Default is 250
           milliseconds.  Allowed range is from 0.01 to 9000.

       makeup
           Set amount of amplification of signal after processing.  Default is
           1. Allowed range is from 1 to 64.

       knee
           Curve the sharp knee around the threshold to enter gain reduction
           more softly.  Default is 2.828427125. Allowed range is from 1 to 8.

       detection
           Choose if exact signal should be taken for detection or an RMS like
           one.  Default is rms. Can be peak or rms.

       link
           Choose if the average level between all channels or the louder
           channel affects the reduction.  Default is average. Can be average
           or maximum.

       level_sc
           Set sidechain gain. Default is 1. Range is from 0.015625 to 64.

       Commands

       This filter supports the all above options as commands.

   silencedetect
       Detect silence in an audio stream.

       This filter logs a message when it detects that the input audio volume
       is less or equal to a noise tolerance value for a duration greater or
       equal to the minimum detected noise duration.

       The printed times and duration are expressed in seconds. The
       "lavfi.silence_start" or "lavfi.silence_start.X" metadata key is set on
       the first frame whose timestamp equals or exceeds the detection
       duration and it contains the timestamp of the first frame of the
       silence.

       The "lavfi.silence_duration" or "lavfi.silence_duration.X" and
       "lavfi.silence_end" or "lavfi.silence_end.X" metadata keys are set on
       the first frame after the silence. If mono is enabled, and each channel
       is evaluated separately, the ".X" suffixed keys are used, and "X"
       corresponds to the channel number.

       The filter accepts the following options:

       noise, n
           Set noise tolerance. Can be specified in dB (in case "dB" is
           appended to the specified value) or amplitude ratio. Default is
           -60dB, or 0.001.

       duration, d
           Set silence duration until notification (default is 2 seconds). See
           the Time duration section in the ffmpeg-utils(1) manual for the
           accepted syntax.

       mono, m
           Process each channel separately, instead of combined. By default is
           disabled.

       Examples

       o   Detect 5 seconds of silence with -50dB noise tolerance:

                   silencedetect=n=-50dB:d=5

       o   Complete example with ffmpeg to detect silence with 0.0001 noise
           tolerance in silence.mp3:

                   ffmpeg -i silence.mp3 -af silencedetect=noise=0.0001 -f null -

   silenceremove
       Remove silence from the beginning, middle or end of the audio.

       The filter accepts the following options:

       start_periods
           This value is used to indicate if audio should be trimmed at
           beginning of the audio. A value of zero indicates no silence should
           be trimmed from the beginning. When specifying a non-zero value, it
           trims audio up until it finds non-silence. Normally, when trimming
           silence from beginning of audio the start_periods will be 1 but it
           can be increased to higher values to trim all audio up to specific
           count of non-silence periods.  Default value is 0.

       start_duration
           Specify the amount of time that non-silence must be detected before
           it stops trimming audio. By increasing the duration, bursts of
           noises can be treated as silence and trimmed off. Default value is
           0.

       start_threshold
           This indicates what sample value should be treated as silence. For
           digital audio, a value of 0 may be fine but for audio recorded from
           analog, you may wish to increase the value to account for
           background noise.  Can be specified in dB (in case "dB" is appended
           to the specified value) or amplitude ratio. Default value is 0.

       start_silence
           Specify max duration of silence at beginning that will be kept
           after trimming. Default is 0, which is equal to trimming all
           samples detected as silence.

       start_mode
           Specify mode of detection of silence end in start of multi-channel
           audio.  Can be any or all. Default is any.  With any, any sample
           that is detected as non-silence will cause stopped trimming of
           silence.  With all, only if all channels are detected as non-
           silence will cause stopped trimming of silence.

       stop_periods
           Set the count for trimming silence from the end of audio.  To
           remove silence from the middle of a file, specify a stop_periods
           that is negative. This value is then treated as a positive value
           and is used to indicate the effect should restart processing as
           specified by start_periods, making it suitable for removing periods
           of silence in the middle of the audio.  Default value is 0.

       stop_duration
           Specify a duration of silence that must exist before audio is not
           copied any more. By specifying a higher duration, silence that is
           wanted can be left in the audio.  Default value is 0.

       stop_threshold
           This is the same as start_threshold but for trimming silence from
           the end of audio.  Can be specified in dB (in case "dB" is appended
           to the specified value) or amplitude ratio. Default value is 0.

       stop_silence
           Specify max duration of silence at end that will be kept after
           trimming. Default is 0, which is equal to trimming all samples
           detected as silence.

       stop_mode
           Specify mode of detection of silence start in end of multi-channel
           audio.  Can be any or all. Default is any.  With any, any sample
           that is detected as non-silence will cause stopped trimming of
           silence.  With all, only if all channels are detected as non-
           silence will cause stopped trimming of silence.

       detection
           Set how is silence detected. Can be "rms" or "peak". Second is
           faster and works better with digital silence which is exactly 0.
           Default value is "rms".

       window
           Set duration in number of seconds used to calculate size of window
           in number of samples for detecting silence.  Default value is 0.02.
           Allowed range is from 0 to 10.

       Examples

       o   The following example shows how this filter can be used to start a
           recording that does not contain the delay at the start which
           usually occurs between pressing the record button and the start of
           the performance:

                   silenceremove=start_periods=1:start_duration=5:start_threshold=0.02

       o   Trim all silence encountered from beginning to end where there is
           more than 1 second of silence in audio:

                   silenceremove=stop_periods=-1:stop_duration=1:stop_threshold=-90dB

       o   Trim all digital silence samples, using peak detection, from
           beginning to end where there is more than 0 samples of digital
           silence in audio and digital silence is detected in all channels at
           same positions in stream:

                   silenceremove=window=0:detection=peak:stop_mode=all:start_mode=all:stop_periods=-1:stop_threshold=0

   sofalizer
       SOFAlizer uses head-related transfer functions (HRTFs) to create
       virtual loudspeakers around the user for binaural listening via
       headphones (audio formats up to 9 channels supported).  The HRTFs are
       stored in SOFA files (see <http://www.sofacoustics.org/> for a
       database).  SOFAlizer is developed at the Acoustics Research Institute
       (ARI) of the Austrian Academy of Sciences.

       To enable compilation of this filter you need to configure FFmpeg with
       "--enable-libmysofa".

       The filter accepts the following options:

       sofa
           Set the SOFA file used for rendering.

       gain
           Set gain applied to audio. Value is in dB. Default is 0.

       rotation
           Set rotation of virtual loudspeakers in deg. Default is 0.

       elevation
           Set elevation of virtual speakers in deg. Default is 0.

       radius
           Set distance in meters between loudspeakers and the listener with
           near-field HRTFs. Default is 1.

       type
           Set processing type. Can be time or freq. time is processing audio
           in time domain which is slow.  freq is processing audio in
           frequency domain which is fast.  Default is freq.

       speakers
           Set custom positions of virtual loudspeakers. Syntax for this
           option is: <CH> <AZIM> <ELEV>[|<CH> <AZIM> <ELEV>|...].  Each
           virtual loudspeaker is described with short channel name following
           with azimuth and elevation in degrees.  Each virtual loudspeaker
           description is separated by '|'.  For example to override front
           left and front right channel positions use: 'speakers=FL 45 15|FR
           345 15'.  Descriptions with unrecognised channel names are ignored.

       lfegain
           Set custom gain for LFE channels. Value is in dB. Default is 0.

       framesize
           Set custom frame size in number of samples. Default is 1024.
           Allowed range is from 1024 to 96000. Only used if option type is
           set to freq.

       normalize
           Should all IRs be normalized upon importing SOFA file.  By default
           is enabled.

       interpolate
           Should nearest IRs be interpolated with neighbor IRs if exact
           position does not match. By default is disabled.

       minphase
           Minphase all IRs upon loading of SOFA file. By default is disabled.

       anglestep
           Set neighbor search angle step. Only used if option interpolate is
           enabled.

       radstep
           Set neighbor search radius step. Only used if option interpolate is
           enabled.

       Examples

       o   Using ClubFritz6 sofa file:

                   sofalizer=sofa=/path/to/ClubFritz6.sofa:type=freq:radius=1

       o   Using ClubFritz12 sofa file and bigger radius with small rotation:

                   sofalizer=sofa=/path/to/ClubFritz12.sofa:type=freq:radius=2:rotation=5

       o   Similar as above but with custom speaker positions for front left,
           front right, back left and back right and also with custom gain:

                   "sofalizer=sofa=/path/to/ClubFritz6.sofa:type=freq:radius=2:speakers=FL 45|FR 315|BL 135|BR 225:gain=28"

   speechnorm
       Speech Normalizer.

       This filter expands or compresses each half-cycle of audio samples
       (local set of samples all above or all below zero and between two
       nearest zero crossings) depending on threshold value, so audio reaches
       target peak value under conditions controlled by below options.

       The filter accepts the following options:

       peak, p
           Set the expansion target peak value. This specifies the highest
           allowed absolute amplitude level for the normalized audio input.
           Default value is 0.95. Allowed range is from 0.0 to 1.0.

       expansion, e
           Set the maximum expansion factor. Allowed range is from 1.0 to
           50.0. Default value is 2.0.  This option controls maximum local
           half-cycle of samples expansion. The maximum expansion would be
           such that local peak value reaches target peak value but never to
           surpass it and that ratio between new and previous peak value does
           not surpass this option value.

       compression, c
           Set the maximum compression factor. Allowed range is from 1.0 to
           50.0. Default value is 2.0.  This option controls maximum local
           half-cycle of samples compression. This option is used only if
           threshold option is set to value greater than 0.0, then in such
           cases when local peak is lower or same as value set by threshold
           all samples belonging to that peak's half-cycle will be compressed
           by current compression factor.

       threshold, t
           Set the threshold value. Default value is 0.0. Allowed range is
           from 0.0 to 1.0.  This option specifies which half-cycles of
           samples will be compressed and which will be expanded.  Any half-
           cycle samples with their local peak value below or same as this
           option value will be compressed by current compression factor,
           otherwise, if greater than threshold value they will be expanded
           with expansion factor so that it could reach peak target value but
           never surpass it.

       raise, r
           Set the expansion raising amount per each half-cycle of samples.
           Default value is 0.001.  Allowed range is from 0.0 to 1.0. This
           controls how fast expansion factor is raised per each new half-
           cycle until it reaches expansion value.  Setting this options too
           high may lead to distortions.

       fall, f
           Set the compression raising amount per each half-cycle of samples.
           Default value is 0.001.  Allowed range is from 0.0 to 1.0. This
           controls how fast compression factor is raised per each new half-
           cycle until it reaches compression value.

       channels, h
           Specify which channels to filter, by default all available channels
           are filtered.

       invert, i
           Enable inverted filtering, by default is disabled. This inverts
           interpretation of threshold option. When enabled any half-cycle of
           samples with their local peak value below or same as threshold
           option will be expanded otherwise it will be compressed.

       link, l
           Link channels when calculating gain applied to each filtered
           channel sample, by default is disabled.  When disabled each
           filtered channel gain calculation is independent, otherwise when
           this option is enabled the minimum of all possible gains for each
           filtered channel is used.

       Commands

       This filter supports the all above options as commands.

   stereotools
       This filter has some handy utilities to manage stereo signals, for
       converting M/S stereo recordings to L/R signal while having control
       over the parameters or spreading the stereo image of master track.

       The filter accepts the following options:

       level_in
           Set input level before filtering for both channels. Defaults is 1.
           Allowed range is from 0.015625 to 64.

       level_out
           Set output level after filtering for both channels. Defaults is 1.
           Allowed range is from 0.015625 to 64.

       balance_in
           Set input balance between both channels. Default is 0.  Allowed
           range is from -1 to 1.

       balance_out
           Set output balance between both channels. Default is 0.  Allowed
           range is from -1 to 1.

       softclip
           Enable softclipping. Results in analog distortion instead of harsh
           digital 0dB clipping. Disabled by default.

       mutel
           Mute the left channel. Disabled by default.

       muter
           Mute the right channel. Disabled by default.

       phasel
           Change the phase of the left channel. Disabled by default.

       phaser
           Change the phase of the right channel. Disabled by default.

       mode
           Set stereo mode. Available values are:

           lr>lr
               Left/Right to Left/Right, this is default.

           lr>ms
               Left/Right to Mid/Side.

           ms>lr
               Mid/Side to Left/Right.

           lr>ll
               Left/Right to Left/Left.

           lr>rr
               Left/Right to Right/Right.

           lr>l+r
               Left/Right to Left + Right.

           lr>rl
               Left/Right to Right/Left.

           ms>ll
               Mid/Side to Left/Left.

           ms>rr
               Mid/Side to Right/Right.

           ms>rl
               Mid/Side to Right/Left.

           lr>l-r
               Left/Right to Left - Right.

       slev
           Set level of side signal. Default is 1.  Allowed range is from
           0.015625 to 64.

       sbal
           Set balance of side signal. Default is 0.  Allowed range is from -1
           to 1.

       mlev
           Set level of the middle signal. Default is 1.  Allowed range is
           from 0.015625 to 64.

       mpan
           Set middle signal pan. Default is 0. Allowed range is from -1 to 1.

       base
           Set stereo base between mono and inversed channels. Default is 0.
           Allowed range is from -1 to 1.

       delay
           Set delay in milliseconds how much to delay left from right channel
           and vice versa. Default is 0. Allowed range is from -20 to 20.

       sclevel
           Set S/C level. Default is 1. Allowed range is from 1 to 100.

       phase
           Set the stereo phase in degrees. Default is 0. Allowed range is
           from 0 to 360.

       bmode_in, bmode_out
           Set balance mode for balance_in/balance_out option.

           Can be one of the following:

           balance
               Classic balance mode. Attenuate one channel at time.  Gain is
               raised up to 1.

           amplitude
               Similar as classic mode above but gain is raised up to 2.

           power
               Equal power distribution, from -6dB to +6dB range.

       Commands

       This filter supports the all above options as commands.

       Examples

       o   Apply karaoke like effect:

                   stereotools=mlev=0.015625

       o   Convert M/S signal to L/R:

                   "stereotools=mode=ms>lr"

   stereowiden
       This filter enhance the stereo effect by suppressing signal common to
       both channels and by delaying the signal of left into right and vice
       versa, thereby widening the stereo effect.

       The filter accepts the following options:

       delay
           Time in milliseconds of the delay of left signal into right and
           vice versa.  Default is 20 milliseconds.

       feedback
           Amount of gain in delayed signal into right and vice versa. Gives a
           delay effect of left signal in right output and vice versa which
           gives widening effect. Default is 0.3.

       crossfeed
           Cross feed of left into right with inverted phase. This helps in
           suppressing the mono. If the value is 1 it will cancel all the
           signal common to both channels. Default is 0.3.

       drymix
           Set level of input signal of original channel. Default is 0.8.

       Commands

       This filter supports the all above options except "delay" as commands.

   superequalizer
       Apply 18 band equalizer.

       The filter accepts the following options:

       1b  Set 65Hz band gain.

       2b  Set 92Hz band gain.

       3b  Set 131Hz band gain.

       4b  Set 185Hz band gain.

       5b  Set 262Hz band gain.

       6b  Set 370Hz band gain.

       7b  Set 523Hz band gain.

       8b  Set 740Hz band gain.

       9b  Set 1047Hz band gain.

       10b Set 1480Hz band gain.

       11b Set 2093Hz band gain.

       12b Set 2960Hz band gain.

       13b Set 4186Hz band gain.

       14b Set 5920Hz band gain.

       15b Set 8372Hz band gain.

       16b Set 11840Hz band gain.

       17b Set 16744Hz band gain.

       18b Set 20000Hz band gain.

   surround
       Apply audio surround upmix filter.

       This filter allows to produce multichannel output from audio stream.

       The filter accepts the following options:

       chl_out
           Set output channel layout. By default, this is 5.1.

           See the Channel Layout section in the ffmpeg-utils(1) manual for
           the required syntax.

       chl_in
           Set input channel layout. By default, this is stereo.

           See the Channel Layout section in the ffmpeg-utils(1) manual for
           the required syntax.

       level_in
           Set input volume level. By default, this is 1.

       level_out
           Set output volume level. By default, this is 1.

       lfe Enable LFE channel output if output channel layout has it. By
           default, this is enabled.

       lfe_low
           Set LFE low cut off frequency. By default, this is 128 Hz.

       lfe_high
           Set LFE high cut off frequency. By default, this is 256 Hz.

       lfe_mode
           Set LFE mode, can be add or sub. Default is add.  In add mode, LFE
           channel is created from input audio and added to output.  In sub
           mode, LFE channel is created from input audio and added to output
           but also all non-LFE output channels are subtracted with output LFE
           channel.

       angle
           Set angle of stereo surround transform, Allowed range is from 0 to
           360.  Default is 90.

       fc_in
           Set front center input volume. By default, this is 1.

       fc_out
           Set front center output volume. By default, this is 1.

       fl_in
           Set front left input volume. By default, this is 1.

       fl_out
           Set front left output volume. By default, this is 1.

       fr_in
           Set front right input volume. By default, this is 1.

       fr_out
           Set front right output volume. By default, this is 1.

       sl_in
           Set side left input volume. By default, this is 1.

       sl_out
           Set side left output volume. By default, this is 1.

       sr_in
           Set side right input volume. By default, this is 1.

       sr_out
           Set side right output volume. By default, this is 1.

       bl_in
           Set back left input volume. By default, this is 1.

       bl_out
           Set back left output volume. By default, this is 1.

       br_in
           Set back right input volume. By default, this is 1.

       br_out
           Set back right output volume. By default, this is 1.

       bc_in
           Set back center input volume. By default, this is 1.

       bc_out
           Set back center output volume. By default, this is 1.

       lfe_in
           Set LFE input volume. By default, this is 1.

       lfe_out
           Set LFE output volume. By default, this is 1.

       allx
           Set spread usage of stereo image across X axis for all channels.

       ally
           Set spread usage of stereo image across Y axis for all channels.

       fcx, flx, frx, blx, brx, slx, srx, bcx
           Set spread usage of stereo image across X axis for each channel.

       fcy, fly, fry, bly, bry, sly, sry, bcy
           Set spread usage of stereo image across Y axis for each channel.

       win_size
           Set window size. Allowed range is from 1024 to 65536. Default size
           is 4096.

       win_func
           Set window function.

           It accepts the following values:

           rect
           bartlett
           hann, hanning
           hamming
           blackman
           welch
           flattop
           bharris
           bnuttall
           bhann
           sine
           nuttall
           lanczos
           gauss
           tukey
           dolph
           cauchy
           parzen
           poisson
           bohman

           Default is "hann".

       overlap
           Set window overlap. If set to 1, the recommended overlap for
           selected window function will be picked. Default is 0.5.

   treble, highshelf
       Boost or cut treble (upper) frequencies of the audio using a two-pole
       shelving filter with a response similar to that of a standard hi-fi's
       tone-controls. This is also known as shelving equalisation (EQ).

       The filter accepts the following options:

       gain, g
           Give the gain at whichever is the lower of ~22 kHz and the Nyquist
           frequency. Its useful range is about -20 (for a large cut) to +20
           (for a large boost). Beware of clipping when using a positive gain.

       frequency, f
           Set the filter's central frequency and so can be used to extend or
           reduce the frequency range to be boosted or cut.  The default value
           is 3000 Hz.

       width_type, t
           Set method to specify band-width of filter.

           h   Hz

           q   Q-Factor

           o   octave

           s   slope

           k   kHz

       width, w
           Determine how steep is the filter's shelf transition.

       poles, p
           Set number of poles. Default is 2.

       mix, m
           How much to use filtered signal in output. Default is 1.  Range is
           between 0 and 1.

       channels, c
           Specify which channels to filter, by default all available are
           filtered.

       normalize, n
           Normalize biquad coefficients, by default is disabled.  Enabling it
           will normalize magnitude response at DC to 0dB.

       transform, a
           Set transform type of IIR filter.

           di
           dii
           tdii
           latt
       precision, r
           Set precison of filtering.

           auto
               Pick automatic sample format depending on surround filters.

           s16 Always use signed 16-bit.

           s32 Always use signed 32-bit.

           f32 Always use float 32-bit.

           f64 Always use float 64-bit.

       Commands

       This filter supports the following commands:

       frequency, f
           Change treble frequency.  Syntax for the command is : "frequency"

       width_type, t
           Change treble width_type.  Syntax for the command is : "width_type"

       width, w
           Change treble width.  Syntax for the command is : "width"

       gain, g
           Change treble gain.  Syntax for the command is : "gain"

       mix, m
           Change treble mix.  Syntax for the command is : "mix"

   tremolo
       Sinusoidal amplitude modulation.

       The filter accepts the following options:

       f   Modulation frequency in Hertz. Modulation frequencies in the
           subharmonic range (20 Hz or lower) will result in a tremolo effect.
           This filter may also be used as a ring modulator by specifying a
           modulation frequency higher than 20 Hz.  Range is 0.1 - 20000.0.
           Default value is 5.0 Hz.

       d   Depth of modulation as a percentage. Range is 0.0 - 1.0.  Default
           value is 0.5.

   vibrato
       Sinusoidal phase modulation.

       The filter accepts the following options:

       f   Modulation frequency in Hertz.  Range is 0.1 - 20000.0. Default
           value is 5.0 Hz.

       d   Depth of modulation as a percentage. Range is 0.0 - 1.0.  Default
           value is 0.5.

   volume
       Adjust the input audio volume.

       It accepts the following parameters:

       volume
           Set audio volume expression.

           Output values are clipped to the maximum value.

           The output audio volume is given by the relation:

                   <output_volume> = <volume> * <input_volume>

           The default value for volume is "1.0".

       precision
           This parameter represents the mathematical precision.

           It determines which input sample formats will be allowed, which
           affects the precision of the volume scaling.

           fixed
               8-bit fixed-point; this limits input sample format to U8, S16,
               and S32.

           float
               32-bit floating-point; this limits input sample format to FLT.
               (default)

           double
               64-bit floating-point; this limits input sample format to DBL.

       replaygain
           Choose the behaviour on encountering ReplayGain side data in input
           frames.

           drop
               Remove ReplayGain side data, ignoring its contents (the
               default).

           ignore
               Ignore ReplayGain side data, but leave it in the frame.

           track
               Prefer the track gain, if present.

           album
               Prefer the album gain, if present.

       replaygain_preamp
           Pre-amplification gain in dB to apply to the selected replaygain
           gain.

           Default value for replaygain_preamp is 0.0.

       replaygain_noclip
           Prevent clipping by limiting the gain applied.

           Default value for replaygain_noclip is 1.

       eval
           Set when the volume expression is evaluated.

           It accepts the following values:

           once
               only evaluate expression once during the filter initialization,
               or when the volume command is sent

           frame
               evaluate expression for each incoming frame

           Default value is once.

       The volume expression can contain the following parameters.

       n   frame number (starting at zero)

       nb_channels
           number of channels

       nb_consumed_samples
           number of samples consumed by the filter

       nb_samples
           number of samples in the current frame

       pos original frame position in the file

       pts frame PTS

       sample_rate
           sample rate

       startpts
           PTS at start of stream

       startt
           time at start of stream

       t   frame time

       tb  timestamp timebase

       volume
           last set volume value

       Note that when eval is set to once only the sample_rate and tb
       variables are available, all other variables will evaluate to NAN.

       Commands

       This filter supports the following commands:

       volume
           Modify the volume expression.  The command accepts the same syntax
           of the corresponding option.

           If the specified expression is not valid, it is kept at its current
           value.

       Examples

       o   Halve the input audio volume:

                   volume=volume=0.5
                   volume=volume=1/2
                   volume=volume=-6.0206dB

           In all the above example the named key for volume can be omitted,
           for example like in:

                   volume=0.5

       o   Increase input audio power by 6 decibels using fixed-point
           precision:

                   volume=volume=6dB:precision=fixed

       o   Fade volume after time 10 with an annihilation period of 5 seconds:

                   volume='if(lt(t,10),1,max(1-(t-10)/5,0))':eval=frame

   volumedetect
       Detect the volume of the input video.

       The filter has no parameters. The input is not modified. Statistics
       about the volume will be printed in the log when the input stream end
       is reached.

       In particular it will show the mean volume (root mean square), maximum
       volume (on a per-sample basis), and the beginning of a histogram of the
       registered volume values (from the maximum value to a cumulated 1/1000
       of the samples).

       All volumes are in decibels relative to the maximum PCM value.

       Examples

       Here is an excerpt of the output:

               [Parsed_volumedetect_0  0xa23120] mean_volume: -27 dB
               [Parsed_volumedetect_0  0xa23120] max_volume: -4 dB
               [Parsed_volumedetect_0  0xa23120] histogram_4db: 6
               [Parsed_volumedetect_0  0xa23120] histogram_5db: 62
               [Parsed_volumedetect_0  0xa23120] histogram_6db: 286
               [Parsed_volumedetect_0  0xa23120] histogram_7db: 1042
               [Parsed_volumedetect_0  0xa23120] histogram_8db: 2551
               [Parsed_volumedetect_0  0xa23120] histogram_9db: 4609
               [Parsed_volumedetect_0  0xa23120] histogram_10db: 8409

       It means that:

       o   The mean square energy is approximately -27 dB, or 10^-2.7.

       o   The largest sample is at -4 dB, or more precisely between -4 dB and
           -5 dB.

       o   There are 6 samples at -4 dB, 62 at -5 dB, 286 at -6 dB, etc.

       In other words, raising the volume by +4 dB does not cause any
       clipping, raising it by +5 dB causes clipping for 6 samples, etc.


AUDIO SOURCES

       Below is a description of the currently available audio sources.

   abuffer
       Buffer audio frames, and make them available to the filter chain.

       This source is mainly intended for a programmatic use, in particular
       through the interface defined in libavfilter/buffersrc.h.

       It accepts the following parameters:

       time_base
           The timebase which will be used for timestamps of submitted frames.
           It must be either a floating-point number or in
           numerator/denominator form.

       sample_rate
           The sample rate of the incoming audio buffers.

       sample_fmt
           The sample format of the incoming audio buffers.  Either a sample
           format name or its corresponding integer representation from the
           enum AVSampleFormat in libavutil/samplefmt.h

       channel_layout
           The channel layout of the incoming audio buffers.  Either a channel
           layout name from channel_layout_map in libavutil/channel_layout.c
           or its corresponding integer representation from the AV_CH_LAYOUT_*
           macros in libavutil/channel_layout.h

       channels
           The number of channels of the incoming audio buffers.  If both
           channels and channel_layout are specified, then they must be
           consistent.

       Examples

               abuffer=sample_rate=44100:sample_fmt=s16p:channel_layout=stereo

       will instruct the source to accept planar 16bit signed stereo at
       44100Hz.  Since the sample format with name "s16p" corresponds to the
       number 6 and the "stereo" channel layout corresponds to the value 0x3,
       this is equivalent to:

               abuffer=sample_rate=44100:sample_fmt=6:channel_layout=0x3

   aevalsrc
       Generate an audio signal specified by an expression.

       This source accepts in input one or more expressions (one for each
       channel), which are evaluated and used to generate a corresponding
       audio signal.

       This source accepts the following options:

       exprs
           Set the '|'-separated expressions list for each separate channel.
           In case the channel_layout option is not specified, the selected
           channel layout depends on the number of provided expressions.
           Otherwise the last specified expression is applied to the remaining
           output channels.

       channel_layout, c
           Set the channel layout. The number of channels in the specified
           layout must be equal to the number of specified expressions.

       duration, d
           Set the minimum duration of the sourced audio. See the Time
           duration section in the ffmpeg-utils(1) manual for the accepted
           syntax.  Note that the resulting duration may be greater than the
           specified duration, as the generated audio is always cut at the end
           of a complete frame.

           If not specified, or the expressed duration is negative, the audio
           is supposed to be generated forever.

       nb_samples, n
           Set the number of samples per channel per each output frame,
           default to 1024.

       sample_rate, s
           Specify the sample rate, default to 44100.

       Each expression in exprs can contain the following constants:

       n   number of the evaluated sample, starting from 0

       t   time of the evaluated sample expressed in seconds, starting from 0

       s   sample rate

       Examples

       o   Generate silence:

                   aevalsrc=0

       o   Generate a sin signal with frequency of 440 Hz, set sample rate to
           8000 Hz:

                   aevalsrc="sin(440*2*PI*t):s=8000"

       o   Generate a two channels signal, specify the channel layout (Front
           Center + Back Center) explicitly:

                   aevalsrc="sin(420*2*PI*t)|cos(430*2*PI*t):c=FC|BC"

       o   Generate white noise:

                   aevalsrc="-2+random(0)"

       o   Generate an amplitude modulated signal:

                   aevalsrc="sin(10*2*PI*t)*sin(880*2*PI*t)"

       o   Generate 2.5 Hz binaural beats on a 360 Hz carrier:

                   aevalsrc="0.1*sin(2*PI*(360-2.5/2)*t) | 0.1*sin(2*PI*(360+2.5/2)*t)"

   afirsrc
       Generate a FIR coefficients using frequency sampling method.

       The resulting stream can be used with afir filter for filtering the
       audio signal.

       The filter accepts the following options:

       taps, t
           Set number of filter coefficents in output audio stream.  Default
           value is 1025.

       frequency, f
           Set frequency points from where magnitude and phase are set.  This
           must be in non decreasing order, and first element must be 0, while
           last element must be 1. Elements are separated by white spaces.

       magnitude, m
           Set magnitude value for every frequency point set by frequency.
           Number of values must be same as number of frequency points.
           Values are separated by white spaces.

       phase, p
           Set phase value for every frequency point set by frequency.  Number
           of values must be same as number of frequency points.  Values are
           separated by white spaces.

       sample_rate, r
           Set sample rate, default is 44100.

       nb_samples, n
           Set number of samples per each frame. Default is 1024.

       win_func, w
           Set window function. Default is blackman.

   anullsrc
       The null audio source, return unprocessed audio frames. It is mainly
       useful as a template and to be employed in analysis / debugging tools,
       or as the source for filters which ignore the input data (for example
       the sox synth filter).

       This source accepts the following options:

       channel_layout, cl
           Specifies the channel layout, and can be either an integer or a
           string representing a channel layout. The default value of
           channel_layout is "stereo".

           Check the channel_layout_map definition in
           libavutil/channel_layout.c for the mapping between strings and
           channel layout values.

       sample_rate, r
           Specifies the sample rate, and defaults to 44100.

       nb_samples, n
           Set the number of samples per requested frames.

       duration, d
           Set the duration of the sourced audio. See the Time duration
           section in the ffmpeg-utils(1) manual for the accepted syntax.

           If not specified, or the expressed duration is negative, the audio
           is supposed to be generated forever.

       Examples

       o   Set the sample rate to 48000 Hz and the channel layout to
           AV_CH_LAYOUT_MONO.

                   anullsrc=r=48000:cl=4

       o   Do the same operation with a more obvious syntax:

                   anullsrc=r=48000:cl=mono

       All the parameters need to be explicitly defined.

   flite
       Synthesize a voice utterance using the libflite library.

       To enable compilation of this filter you need to configure FFmpeg with
       "--enable-libflite".

       Note that versions of the flite library prior to 2.0 are not thread-
       safe.

       The filter accepts the following options:

       list_voices
           If set to 1, list the names of the available voices and exit
           immediately. Default value is 0.

       nb_samples, n
           Set the maximum number of samples per frame. Default value is 512.

       textfile
           Set the filename containing the text to speak.

       text
           Set the text to speak.

       voice, v
           Set the voice to use for the speech synthesis. Default value is
           "kal". See also the list_voices option.

       Examples

       o   Read from file speech.txt, and synthesize the text using the
           standard flite voice:

                   flite=textfile=speech.txt

       o   Read the specified text selecting the "slt" voice:

                   flite=text='So fare thee well, poor devil of a Sub-Sub, whose commentator I am':voice=slt

       o   Input text to ffmpeg:

                   ffmpeg -f lavfi -i flite=text='So fare thee well, poor devil of a Sub-Sub, whose commentator I am':voice=slt

       o   Make ffplay speak the specified text, using "flite" and the "lavfi"
           device:

                   ffplay -f lavfi flite=text='No more be grieved for which that thou hast done.'

       For more information about libflite, check:
       <http://www.festvox.org/flite/>

   anoisesrc
       Generate a noise audio signal.

       The filter accepts the following options:

       sample_rate, r
           Specify the sample rate. Default value is 48000 Hz.

       amplitude, a
           Specify the amplitude (0.0 - 1.0) of the generated audio stream.
           Default value is 1.0.

       duration, d
           Specify the duration of the generated audio stream. Not specifying
           this option results in noise with an infinite length.

       color, colour, c
           Specify the color of noise. Available noise colors are white, pink,
           brown, blue, violet and velvet. Default color is white.

       seed, s
           Specify a value used to seed the PRNG.

       nb_samples, n
           Set the number of samples per each output frame, default is 1024.

       Examples

       o   Generate 60 seconds of pink noise, with a 44.1 kHz sampling rate
           and an amplitude of 0.5:

                   anoisesrc=d=60:c=pink:r=44100:a=0.5

   hilbert
       Generate odd-tap Hilbert transform FIR coefficients.

       The resulting stream can be used with afir filter for phase-shifting
       the signal by 90 degrees.

       This is used in many matrix coding schemes and for analytic signal
       generation.  The process is often written as a multiplication by i (or
       j), the imaginary unit.

       The filter accepts the following options:

       sample_rate, s
           Set sample rate, default is 44100.

       taps, t
           Set length of FIR filter, default is 22051.

       nb_samples, n
           Set number of samples per each frame.

       win_func, w
           Set window function to be used when generating FIR coefficients.

   sinc
       Generate a sinc kaiser-windowed low-pass, high-pass, band-pass, or
       band-reject FIR coefficients.

       The resulting stream can be used with afir filter for filtering the
       audio signal.

       The filter accepts the following options:

       sample_rate, r
           Set sample rate, default is 44100.

       nb_samples, n
           Set number of samples per each frame. Default is 1024.

       hp  Set high-pass frequency. Default is 0.

       lp  Set low-pass frequency. Default is 0.  If high-pass frequency is
           lower than low-pass frequency and low-pass frequency is higher than
           0 then filter will create band-pass filter coefficients, otherwise
           band-reject filter coefficients.

       phase
           Set filter phase response. Default is 50. Allowed range is from 0
           to 100.

       beta
           Set Kaiser window beta.

       att Set stop-band attenuation. Default is 120dB, allowed range is from
           40 to 180 dB.

       round
           Enable rounding, by default is disabled.

       hptaps
           Set number of taps for high-pass filter.

       lptaps
           Set number of taps for low-pass filter.

   sine
       Generate an audio signal made of a sine wave with amplitude 1/8.

       The audio signal is bit-exact.

       The filter accepts the following options:

       frequency, f
           Set the carrier frequency. Default is 440 Hz.

       beep_factor, b
           Enable a periodic beep every second with frequency beep_factor
           times the carrier frequency. Default is 0, meaning the beep is
           disabled.

       sample_rate, r
           Specify the sample rate, default is 44100.

       duration, d
           Specify the duration of the generated audio stream.

       samples_per_frame
           Set the number of samples per output frame.

           The expression can contain the following constants:

           n   The (sequential) number of the output audio frame, starting
               from 0.

           pts The PTS (Presentation TimeStamp) of the output audio frame,
               expressed in TB units.

           t   The PTS of the output audio frame, expressed in seconds.

           TB  The timebase of the output audio frames.

           Default is 1024.

       Examples

       o   Generate a simple 440 Hz sine wave:

                   sine

       o   Generate a 220 Hz sine wave with a 880 Hz beep each second, for 5
           seconds:

                   sine=220:4:d=5
                   sine=f=220:b=4:d=5
                   sine=frequency=220:beep_factor=4:duration=5

       o   Generate a 1 kHz sine wave following "1602,1601,1602,1601,1602"
           NTSC pattern:

                   sine=1000:samples_per_frame='st(0,mod(n,5)); 1602-not(not(eq(ld(0),1)+eq(ld(0),3)))'


AUDIO SINKS

       Below is a description of the currently available audio sinks.

   abuffersink
       Buffer audio frames, and make them available to the end of filter
       chain.

       This sink is mainly intended for programmatic use, in particular
       through the interface defined in libavfilter/buffersink.h or the
       options system.

       It accepts a pointer to an AVABufferSinkContext structure, which
       defines the incoming buffers' formats, to be passed as the opaque
       parameter to "avfilter_init_filter" for initialization.

   anullsink
       Null audio sink; do absolutely nothing with the input audio. It is
       mainly useful as a template and for use in analysis / debugging tools.


VIDEO FILTERS

       When you configure your FFmpeg build, you can disable any of the
       existing filters using "--disable-filters".  The configure output will
       show the video filters included in your build.

       Below is a description of the currently available video filters.

   addroi
       Mark a region of interest in a video frame.

       The frame data is passed through unchanged, but metadata is attached to
       the frame indicating regions of interest which can affect the behaviour
       of later encoding.  Multiple regions can be marked by applying the
       filter multiple times.

       x   Region distance in pixels from the left edge of the frame.

       y   Region distance in pixels from the top edge of the frame.

       w   Region width in pixels.

       h   Region height in pixels.

           The parameters x, y, w and h are expressions, and may contain the
           following variables:

           iw  Width of the input frame.

           ih  Height of the input frame.

       qoffset
           Quantisation offset to apply within the region.

           This must be a real value in the range -1 to +1.  A value of zero
           indicates no quality change.  A negative value asks for better
           quality (less quantisation), while a positive value asks for worse
           quality (greater quantisation).

           The range is calibrated so that the extreme values indicate the
           largest possible offset - if the rest of the frame is encoded with
           the worst possible quality, an offset of -1 indicates that this
           region should be encoded with the best possible quality anyway.
           Intermediate values are then interpolated in some codec-dependent
           way.

           For example, in 10-bit H.264 the quantisation parameter varies
           between -12 and 51.  A typical qoffset value of -1/10 therefore
           indicates that this region should be encoded with a QP around one-
           tenth of the full range better than the rest of the frame.  So, if
           most of the frame were to be encoded with a QP of around 30, this
           region would get a QP of around 24 (an offset of approximately
           -1/10 * (51 - -12) = -6.3).  An extreme value of -1 would indicate
           that this region should be encoded with the best possible quality
           regardless of the treatment of the rest of the frame - that is,
           should be encoded at a QP of -12.

       clear
           If set to true, remove any existing regions of interest marked on
           the frame before adding the new one.

       Examples

       o   Mark the centre quarter of the frame as interesting.

                   addroi=iw/4:ih/4:iw/2:ih/2:-1/10

       o   Mark the 100-pixel-wide region on the left edge of the frame as
           very uninteresting (to be encoded at much lower quality than the
           rest of the frame).

                   addroi=0:0:100:ih:+1/5

   alphaextract
       Extract the alpha component from the input as a grayscale video. This
       is especially useful with the alphamerge filter.

   alphamerge
       Add or replace the alpha component of the primary input with the
       grayscale value of a second input. This is intended for use with
       alphaextract to allow the transmission or storage of frame sequences
       that have alpha in a format that doesn't support an alpha channel.

       For example, to reconstruct full frames from a normal YUV-encoded video
       and a separate video created with alphaextract, you might use:

               movie=in_alpha.mkv [alpha]; [in][alpha] alphamerge [out]

   amplify
       Amplify differences between current pixel and pixels of adjacent frames
       in same pixel location.

       This filter accepts the following options:

       radius
           Set frame radius. Default is 2. Allowed range is from 1 to 63.  For
           example radius of 3 will instruct filter to calculate average of 7
           frames.

       factor
           Set factor to amplify difference. Default is 2. Allowed range is
           from 0 to 65535.

       threshold
           Set threshold for difference amplification. Any difference greater
           or equal to this value will not alter source pixel. Default is 10.
           Allowed range is from 0 to 65535.

       tolerance
           Set tolerance for difference amplification. Any difference lower to
           this value will not alter source pixel. Default is 0.  Allowed
           range is from 0 to 65535.

       low Set lower limit for changing source pixel. Default is 65535.
           Allowed range is from 0 to 65535.  This option controls maximum
           possible value that will decrease source pixel value.

       high
           Set high limit for changing source pixel. Default is 65535. Allowed
           range is from 0 to 65535.  This option controls maximum possible
           value that will increase source pixel value.

       planes
           Set which planes to filter. Default is all. Allowed range is from 0
           to 15.

       Commands

       This filter supports the following commands that corresponds to option
       of same name:

       factor
       threshold
       tolerance
       low
       high
       planes

   ass
       Same as the subtitles filter, except that it doesn't require libavcodec
       and libavformat to work. On the other hand, it is limited to ASS
       (Advanced Substation Alpha) subtitles files.

       This filter accepts the following option in addition to the common
       options from the subtitles filter:

       shaping
           Set the shaping engine

           Available values are:

           auto
               The default libass shaping engine, which is the best available.

           simple
               Fast, font-agnostic shaper that can do only substitutions

           complex
               Slower shaper using OpenType for substitutions and positioning

           The default is "auto".

   atadenoise
       Apply an Adaptive Temporal Averaging Denoiser to the video input.

       The filter accepts the following options:

       0a  Set threshold A for 1st plane. Default is 0.02.  Valid range is 0
           to 0.3.

       0b  Set threshold B for 1st plane. Default is 0.04.  Valid range is 0
           to 5.

       1a  Set threshold A for 2nd plane. Default is 0.02.  Valid range is 0
           to 0.3.

       1b  Set threshold B for 2nd plane. Default is 0.04.  Valid range is 0
           to 5.

       2a  Set threshold A for 3rd plane. Default is 0.02.  Valid range is 0
           to 0.3.

       2b  Set threshold B for 3rd plane. Default is 0.04.  Valid range is 0
           to 5.

           Threshold A is designed to react on abrupt changes in the input
           signal and threshold B is designed to react on continuous changes
           in the input signal.

       s   Set number of frames filter will use for averaging. Default is 9.
           Must be odd number in range [5, 129].

       p   Set what planes of frame filter will use for averaging. Default is
           all.

       a   Set what variant of algorithm filter will use for averaging.
           Default is "p" parallel.  Alternatively can be set to "s" serial.

           Parallel can be faster then serial, while other way around is never
           true.  Parallel will abort early on first change being greater then
           thresholds, while serial will continue processing other side of
           frames if they are equal or below thresholds.

       0s
       1s
       2s  Set sigma for 1st plane, 2nd plane or 3rd plane. Default is 32767.
           Valid range is from 0 to 32767.  This options controls weight for
           each pixel in radius defined by size.  Default value means every
           pixel have same weight.  Setting this option to 0 effectively
           disables filtering.

       Commands

       This filter supports same commands as options except option "s".  The
       command accepts the same syntax of the corresponding option.

   avgblur
       Apply average blur filter.

       The filter accepts the following options:

       sizeX
           Set horizontal radius size.

       planes
           Set which planes to filter. By default all planes are filtered.

       sizeY
           Set vertical radius size, if zero it will be same as "sizeX".
           Default is 0.

       Commands

       This filter supports same commands as options.  The command accepts the
       same syntax of the corresponding option.

       If the specified expression is not valid, it is kept at its current
       value.

   bbox
       Compute the bounding box for the non-black pixels in the input frame
       luminance plane.

       This filter computes the bounding box containing all the pixels with a
       luminance value greater than the minimum allowed value.  The parameters
       describing the bounding box are printed on the filter log.

       The filter accepts the following option:

       min_val
           Set the minimal luminance value. Default is 16.

       Commands

       This filter supports the all above options as commands.

   bilateral
       Apply bilateral filter, spatial smoothing while preserving edges.

       The filter accepts the following options:

       sigmaS
           Set sigma of gaussian function to calculate spatial weight.
           Allowed range is 0 to 512. Default is 0.1.

       sigmaR
           Set sigma of gaussian function to calculate range weight.  Allowed
           range is 0 to 1. Default is 0.1.

       planes
           Set planes to filter. Default is first only.

       Commands

       This filter supports the all above options as commands.

   bitplanenoise
       Show and measure bit plane noise.

       The filter accepts the following options:

       bitplane
           Set which plane to analyze. Default is 1.

       filter
           Filter out noisy pixels from "bitplane" set above.  Default is
           disabled.

   blackdetect
       Detect video intervals that are (almost) completely black. Can be
       useful to detect chapter transitions, commercials, or invalid
       recordings.

       The filter outputs its detection analysis to both the log as well as
       frame metadata. If a black segment of at least the specified minimum
       duration is found, a line with the start and end timestamps as well as
       duration is printed to the log with level "info". In addition, a log
       line with level "debug" is printed per frame showing the black amount
       detected for that frame.

       The filter also attaches metadata to the first frame of a black segment
       with key "lavfi.black_start" and to the first frame after the black
       segment ends with key "lavfi.black_end". The value is the frame's
       timestamp. This metadata is added regardless of the minimum duration
       specified.

       The filter accepts the following options:

       black_min_duration, d
           Set the minimum detected black duration expressed in seconds. It
           must be a non-negative floating point number.

           Default value is 2.0.

       picture_black_ratio_th, pic_th
           Set the threshold for considering a picture "black".  Express the
           minimum value for the ratio:

                   <nb_black_pixels> / <nb_pixels>

           for which a picture is considered black.  Default value is 0.98.

       pixel_black_th, pix_th
           Set the threshold for considering a pixel "black".

           The threshold expresses the maximum pixel luminance value for which
           a pixel is considered "black". The provided value is scaled
           according to the following equation:

                   <absolute_threshold> = <luminance_minimum_value> + <pixel_black_th> * <luminance_range_size>

           luminance_range_size and luminance_minimum_value depend on the
           input video format, the range is [0-255] for YUV full-range formats
           and [16-235] for YUV non full-range formats.

           Default value is 0.10.

       The following example sets the maximum pixel threshold to the minimum
       value, and detects only black intervals of 2 or more seconds:

               blackdetect=d=2:pix_th=0.00

   blackframe
       Detect frames that are (almost) completely black. Can be useful to
       detect chapter transitions or commercials. Output lines consist of the
       frame number of the detected frame, the percentage of blackness, the
       position in the file if known or -1 and the timestamp in seconds.

       In order to display the output lines, you need to set the loglevel at
       least to the AV_LOG_INFO value.

       This filter exports frame metadata "lavfi.blackframe.pblack".  The
       value represents the percentage of pixels in the picture that are below
       the threshold value.

       It accepts the following parameters:

       amount
           The percentage of the pixels that have to be below the threshold;
           it defaults to 98.

       threshold, thresh
           The threshold below which a pixel value is considered black; it
           defaults to 32.

   blend
       Blend two video frames into each other.

       The "blend" filter takes two input streams and outputs one stream, the
       first input is the "top" layer and second input is "bottom" layer.  By
       default, the output terminates when the longest input terminates.

       The "tblend" (time blend) filter takes two consecutive frames from one
       single stream, and outputs the result obtained by blending the new
       frame on top of the old frame.

       A description of the accepted options follows.

       c0_mode
       c1_mode
       c2_mode
       c3_mode
       all_mode
           Set blend mode for specific pixel component or all pixel components
           in case of all_mode. Default value is "normal".

           Available values for component modes are:

           addition
           grainmerge
           and
           average
           burn
           darken
           difference
           grainextract
           divide
           dodge
           freeze
           exclusion
           extremity
           glow
           hardlight
           hardmix
           heat
           lighten
           linearlight
           multiply
           multiply128
           negation
           normal
           or
           overlay
           phoenix
           pinlight
           reflect
           screen
           softlight
           subtract
           vividlight
           xor
       c0_opacity
       c1_opacity
       c2_opacity
       c3_opacity
       all_opacity
           Set blend opacity for specific pixel component or all pixel
           components in case of all_opacity. Only used in combination with
           pixel component blend modes.

       c0_expr
       c1_expr
       c2_expr
       c3_expr
       all_expr
           Set blend expression for specific pixel component or all pixel
           components in case of all_expr. Note that related mode options will
           be ignored if those are set.

           The expressions can use the following variables:

           N   The sequential number of the filtered frame, starting from 0.

           X
           Y   the coordinates of the current sample

           W
           H   the width and height of currently filtered plane

           SW
           SH  Width and height scale for the plane being filtered. It is the
               ratio between the dimensions of the current plane to the luma
               plane, e.g. for a "yuv420p" frame, the values are "1,1" for the
               luma plane and "0.5,0.5" for the chroma planes.

           T   Time of the current frame, expressed in seconds.

           TOP, A
               Value of pixel component at current location for first video
               frame (top layer).

           BOTTOM, B
               Value of pixel component at current location for second video
               frame (bottom layer).

       The "blend" filter also supports the framesync options.

       Examples

       o   Apply transition from bottom layer to top layer in first 10
           seconds:

                   blend=all_expr='A*(if(gte(T,10),1,T/10))+B*(1-(if(gte(T,10),1,T/10)))'

       o   Apply linear horizontal transition from top layer to bottom layer:

                   blend=all_expr='A*(X/W)+B*(1-X/W)'

       o   Apply 1x1 checkerboard effect:

                   blend=all_expr='if(eq(mod(X,2),mod(Y,2)),A,B)'

       o   Apply uncover left effect:

                   blend=all_expr='if(gte(N*SW+X,W),A,B)'

       o   Apply uncover down effect:

                   blend=all_expr='if(gte(Y-N*SH,0),A,B)'

       o   Apply uncover up-left effect:

                   blend=all_expr='if(gte(T*SH*40+Y,H)*gte((T*40*SW+X)*W/H,W),A,B)'

       o   Split diagonally video and shows top and bottom layer on each side:

                   blend=all_expr='if(gt(X,Y*(W/H)),A,B)'

       o   Display differences between the current and the previous frame:

                   tblend=all_mode=grainextract

       Commands

       This filter supports same commands as options.

   bm3d
       Denoise frames using Block-Matching 3D algorithm.

       The filter accepts the following options.

       sigma
           Set denoising strength. Default value is 1.  Allowed range is from
           0 to 999.9.  The denoising algorithm is very sensitive to sigma, so
           adjust it according to the source.

       block
           Set local patch size. This sets dimensions in 2D.

       bstep
           Set sliding step for processing blocks. Default value is 4.
           Allowed range is from 1 to 64.  Smaller values allows processing
           more reference blocks and is slower.

       group
           Set maximal number of similar blocks for 3rd dimension. Default
           value is 1.  When set to 1, no block matching is done. Larger
           values allows more blocks in single group.  Allowed range is from 1
           to 256.

       range
           Set radius for search block matching. Default is 9.  Allowed range
           is from 1 to INT32_MAX.

       mstep
           Set step between two search locations for block matching. Default
           is 1.  Allowed range is from 1 to 64. Smaller is slower.

       thmse
           Set threshold of mean square error for block matching. Valid range
           is 0 to INT32_MAX.

       hdthr
           Set thresholding parameter for hard thresholding in 3D transformed
           domain.  Larger values results in stronger hard-thresholding
           filtering in frequency domain.

       estim
           Set filtering estimation mode. Can be "basic" or "final".  Default
           is "basic".

       ref If enabled, filter will use 2nd stream for block matching.  Default
           is disabled for "basic" value of estim option, and always enabled
           if value of estim is "final".

       planes
           Set planes to filter. Default is all available except alpha.

       Examples

       o   Basic filtering with bm3d:

                   bm3d=sigma=3:block=4:bstep=2:group=1:estim=basic

       o   Same as above, but filtering only luma:

                   bm3d=sigma=3:block=4:bstep=2:group=1:estim=basic:planes=1

       o   Same as above, but with both estimation modes:

                   split[a][b],[a]bm3d=sigma=3:block=4:bstep=2:group=1:estim=basic[a],[b][a]bm3d=sigma=3:block=4:bstep=2:group=16:estim=final:ref=1

       o   Same as above, but prefilter with nlmeans filter instead:

                   split[a][b],[a]nlmeans=s=3:r=7:p=3[a],[b][a]bm3d=sigma=3:block=4:bstep=2:group=16:estim=final:ref=1

   boxblur
       Apply a boxblur algorithm to the input video.

       It accepts the following parameters:

       luma_radius, lr
       luma_power, lp
       chroma_radius, cr
       chroma_power, cp
       alpha_radius, ar
       alpha_power, ap

       A description of the accepted options follows.

       luma_radius, lr
       chroma_radius, cr
       alpha_radius, ar
           Set an expression for the box radius in pixels used for blurring
           the corresponding input plane.

           The radius value must be a non-negative number, and must not be
           greater than the value of the expression "min(w,h)/2" for the luma
           and alpha planes, and of "min(cw,ch)/2" for the chroma planes.

           Default value for luma_radius is "2". If not specified,
           chroma_radius and alpha_radius default to the corresponding value
           set for luma_radius.

           The expressions can contain the following constants:

           w
           h   The input width and height in pixels.

           cw
           ch  The input chroma image width and height in pixels.

           hsub
           vsub
               The horizontal and vertical chroma subsample values. For
               example, for the pixel format "yuv422p", hsub is 2 and vsub is
               1.

       luma_power, lp
       chroma_power, cp
       alpha_power, ap
           Specify how many times the boxblur filter is applied to the
           corresponding plane.

           Default value for luma_power is 2. If not specified, chroma_power
           and alpha_power default to the corresponding value set for
           luma_power.

           A value of 0 will disable the effect.

       Examples

       o   Apply a boxblur filter with the luma, chroma, and alpha radii set
           to 2:

                   boxblur=luma_radius=2:luma_power=1
                   boxblur=2:1

       o   Set the luma radius to 2, and alpha and chroma radius to 0:

                   boxblur=2:1:cr=0:ar=0

       o   Set the luma and chroma radii to a fraction of the video dimension:

                   boxblur=luma_radius=min(h\,w)/10:luma_power=1:chroma_radius=min(cw\,ch)/10:chroma_power=1

   bwdif
       Deinterlace the input video ("bwdif" stands for "Bob Weaver
       Deinterlacing Filter").

       Motion adaptive deinterlacing based on yadif with the use of w3fdif and
       cubic interpolation algorithms.  It accepts the following parameters:

       mode
           The interlacing mode to adopt. It accepts one of the following
           values:

           0, send_frame
               Output one frame for each frame.

           1, send_field
               Output one frame for each field.

           The default value is "send_field".

       parity
           The picture field parity assumed for the input interlaced video. It
           accepts one of the following values:

           0, tff
               Assume the top field is first.

           1, bff
               Assume the bottom field is first.

           -1, auto
               Enable automatic detection of field parity.

           The default value is "auto".  If the interlacing is unknown or the
           decoder does not export this information, top field first will be
           assumed.

       deint
           Specify which frames to deinterlace. Accepts one of the following
           values:

           0, all
               Deinterlace all frames.

           1, interlaced
               Only deinterlace frames marked as interlaced.

           The default value is "all".

   cas
       Apply Contrast Adaptive Sharpen filter to video stream.

       The filter accepts the following options:

       strength
           Set the sharpening strength. Default value is 0.

       planes
           Set planes to filter. Default value is to filter all planes except
           alpha plane.

       Commands

       This filter supports same commands as options.

   chromahold
       Remove all color information for all colors except for certain one.

       The filter accepts the following options:

       color
           The color which will not be replaced with neutral chroma.

       similarity
           Similarity percentage with the above color.  0.01 matches only the
           exact key color, while 1.0 matches everything.

       blend
           Blend percentage.  0.0 makes pixels either fully gray, or not gray
           at all.  Higher values result in more preserved color.

       yuv Signals that the color passed is already in YUV instead of RGB.

           Literal colors like "green" or "red" don't make sense with this
           enabled anymore.  This can be used to pass exact YUV values as
           hexadecimal numbers.

       Commands

       This filter supports same commands as options.  The command accepts the
       same syntax of the corresponding option.

       If the specified expression is not valid, it is kept at its current
       value.

   chromakey
       YUV colorspace color/chroma keying.

       The filter accepts the following options:

       color
           The color which will be replaced with transparency.

       similarity
           Similarity percentage with the key color.

           0.01 matches only the exact key color, while 1.0 matches
           everything.

       blend
           Blend percentage.

           0.0 makes pixels either fully transparent, or not transparent at
           all.

           Higher values result in semi-transparent pixels, with a higher
           transparency the more similar the pixels color is to the key color.

       yuv Signals that the color passed is already in YUV instead of RGB.

           Literal colors like "green" or "red" don't make sense with this
           enabled anymore.  This can be used to pass exact YUV values as
           hexadecimal numbers.

       Commands

       This filter supports same commands as options.  The command accepts the
       same syntax of the corresponding option.

       If the specified expression is not valid, it is kept at its current
       value.

       Examples

       o   Make every green pixel in the input image transparent:

                   ffmpeg -i input.png -vf chromakey=green out.png

       o   Overlay a greenscreen-video on top of a static black background.

                   ffmpeg -f lavfi -i color=c=black:s=1280x720 -i video.mp4 -shortest -filter_complex "[1:v]chromakey=0x70de77:0.1:0.2[ckout];[0:v][ckout]overlay[out]" -map "[out]" output.mkv

   chromanr
       Reduce chrominance noise.

       The filter accepts the following options:

       thres
           Set threshold for averaging chrominance values.  Sum of absolute
           difference of Y, U and V pixel components of current pixel and
           neighbour pixels lower than this threshold will be used in
           averaging. Luma component is left unchanged and is copied to
           output.  Default value is 30. Allowed range is from 1 to 200.

       sizew
           Set horizontal radius of rectangle used for averaging.  Allowed
           range is from 1 to 100. Default value is 5.

       sizeh
           Set vertical radius of rectangle used for averaging.  Allowed range
           is from 1 to 100. Default value is 5.

       stepw
           Set horizontal step when averaging. Default value is 1.  Allowed
           range is from 1 to 50.  Mostly useful to speed-up filtering.

       steph
           Set vertical step when averaging. Default value is 1.  Allowed
           range is from 1 to 50.  Mostly useful to speed-up filtering.

       threy
           Set Y threshold for averaging chrominance values.  Set finer
           control for max allowed difference between Y components of current
           pixel and neigbour pixels.  Default value is 200. Allowed range is
           from 1 to 200.

       threu
           Set U threshold for averaging chrominance values.  Set finer
           control for max allowed difference between U components of current
           pixel and neigbour pixels.  Default value is 200. Allowed range is
           from 1 to 200.

       threv
           Set V threshold for averaging chrominance values.  Set finer
           control for max allowed difference between V components of current
           pixel and neigbour pixels.  Default value is 200. Allowed range is
           from 1 to 200.

       Commands

       This filter supports same commands as options.  The command accepts the
       same syntax of the corresponding option.

   chromashift
       Shift chroma pixels horizontally and/or vertically.

       The filter accepts the following options:

       cbh Set amount to shift chroma-blue horizontally.

       cbv Set amount to shift chroma-blue vertically.

       crh Set amount to shift chroma-red horizontally.

       crv Set amount to shift chroma-red vertically.

       edge
           Set edge mode, can be smear, default, or warp.

       Commands

       This filter supports the all above options as commands.

   ciescope
       Display CIE color diagram with pixels overlaid onto it.

       The filter accepts the following options:

       system
           Set color system.

           ntsc, 470m
           ebu, 470bg
           smpte
           240m
           apple
           widergb
           cie1931
           rec709, hdtv
           uhdtv, rec2020
           dcip3
       cie Set CIE system.

           xyy
           ucs
           luv
       gamuts
           Set what gamuts to draw.

           See "system" option for available values.

       size, s
           Set ciescope size, by default set to 512.

       intensity, i
           Set intensity used to map input pixel values to CIE diagram.

       contrast
           Set contrast used to draw tongue colors that are out of active
           color system gamut.

       corrgamma
           Correct gamma displayed on scope, by default enabled.

       showwhite
           Show white point on CIE diagram, by default disabled.

       gamma
           Set input gamma. Used only with XYZ input color space.

   codecview
       Visualize information exported by some codecs.

       Some codecs can export information through frames using side-data or
       other means. For example, some MPEG based codecs export motion vectors
       through the export_mvs flag in the codec flags2 option.

       The filter accepts the following option:

       mv  Set motion vectors to visualize.

           Available flags for mv are:

           pf  forward predicted MVs of P-frames

           bf  forward predicted MVs of B-frames

           bb  backward predicted MVs of B-frames

       qp  Display quantization parameters using the chroma planes.

       mv_type, mvt
           Set motion vectors type to visualize. Includes MVs from all frames
           unless specified by frame_type option.

           Available flags for mv_type are:

           fp  forward predicted MVs

           bp  backward predicted MVs

       frame_type, ft
           Set frame type to visualize motion vectors of.

           Available flags for frame_type are:

           if  intra-coded frames (I-frames)

           pf  predicted frames (P-frames)

           bf  bi-directionally predicted frames (B-frames)

       Examples

       o   Visualize forward predicted MVs of all frames using ffplay:

                   ffplay -flags2 +export_mvs input.mp4 -vf codecview=mv_type=fp

       o   Visualize multi-directionals MVs of P and B-Frames using ffplay:

                   ffplay -flags2 +export_mvs input.mp4 -vf codecview=mv=pf+bf+bb

   colorbalance
       Modify intensity of primary colors (red, green and blue) of input
       frames.

       The filter allows an input frame to be adjusted in the shadows,
       midtones or highlights regions for the red-cyan, green-magenta or blue-
       yellow balance.

       A positive adjustment value shifts the balance towards the primary
       color, a negative value towards the complementary color.

       The filter accepts the following options:

       rs
       gs
       bs  Adjust red, green and blue shadows (darkest pixels).

       rm
       gm
       bm  Adjust red, green and blue midtones (medium pixels).

       rh
       gh
       bh  Adjust red, green and blue highlights (brightest pixels).

           Allowed ranges for options are "[-1.0, 1.0]". Defaults are 0.

       pl  Preserve lightness when changing color balance. Default is
           disabled.

       Examples

       o   Add red color cast to shadows:

                   colorbalance=rs=.3

       Commands

       This filter supports the all above options as commands.

   colorcontrast
       Adjust color contrast between RGB components.

       The filter accepts the following options:

       rc  Set the red-cyan contrast. Defaults is 0.0. Allowed range is from
           -1.0 to 1.0.

       gm  Set the green-magenta contrast. Defaults is 0.0. Allowed range is
           from -1.0 to 1.0.

       by  Set the blue-yellow contrast. Defaults is 0.0. Allowed range is
           from -1.0 to 1.0.

       rcw
       gmw
       byw Set the weight of each "rc", "gm", "by" option value. Default value
           is 0.0.  Allowed range is from 0.0 to 1.0. If all weights are 0.0
           filtering is disabled.

       pl  Set the amount of preserving lightness. Default value is 0.0.
           Allowed range is from 0.0 to 1.0.

       Commands

       This filter supports the all above options as commands.

   colorcorrect
       Adjust color white balance selectively for blacks and whites.  This
       filter operates in YUV colorspace.

       The filter accepts the following options:

       rl  Set the red shadow spot. Allowed range is from -1.0 to 1.0.
           Default value is 0.

       bl  Set the blue shadow spot. Allowed range is from -1.0 to 1.0.
           Default value is 0.

       rh  Set the red highlight spot. Allowed range is from -1.0 to 1.0.
           Default value is 0.

       bh  Set the red highlight spot. Allowed range is from -1.0 to 1.0.
           Default value is 0.

       saturation
           Set the amount of saturation. Allowed range is from -3.0 to 3.0.
           Default value is 1.

       Commands

       This filter supports the all above options as commands.

   colorchannelmixer
       Adjust video input frames by re-mixing color channels.

       This filter modifies a color channel by adding the values associated to
       the other channels of the same pixels. For example if the value to
       modify is red, the output value will be:

               <red>=<red>*<rr> + <blue>*<rb> + <green>*<rg> + <alpha>*<ra>

       The filter accepts the following options:

       rr
       rg
       rb
       ra  Adjust contribution of input red, green, blue and alpha channels
           for output red channel.  Default is 1 for rr, and 0 for rg, rb and
           ra.

       gr
       gg
       gb
       ga  Adjust contribution of input red, green, blue and alpha channels
           for output green channel.  Default is 1 for gg, and 0 for gr, gb
           and ga.

       br
       bg
       bb
       ba  Adjust contribution of input red, green, blue and alpha channels
           for output blue channel.  Default is 1 for bb, and 0 for br, bg and
           ba.

       ar
       ag
       ab
       aa  Adjust contribution of input red, green, blue and alpha channels
           for output alpha channel.  Default is 1 for aa, and 0 for ar, ag
           and ab.

           Allowed ranges for options are "[-2.0, 2.0]".

       pl  Preserve lightness when changing colors. Allowed range is from
           "[0.0, 1.0]".  Default is 0.0, thus disabled.

       Examples

       o   Convert source to grayscale:

                   colorchannelmixer=.3:.4:.3:0:.3:.4:.3:0:.3:.4:.3

       o   Simulate sepia tones:

                   colorchannelmixer=.393:.769:.189:0:.349:.686:.168:0:.272:.534:.131

       Commands

       This filter supports the all above options as commands.

   colorize
       Overlay a solid color on the video stream.

       The filter accepts the following options:

       hue Set the color hue. Allowed range is from 0 to 360.  Default value
           is 0.

       saturation
           Set the color saturation. Allowed range is from 0 to 1.  Default
           value is 0.5.

       lightness
           Set the color lightness. Allowed range is from 0 to 1.  Default
           value is 0.5.

       mix Set the mix of source lightness. By default is set to 1.0.  Allowed
           range is from 0.0 to 1.0.

       Commands

       This filter supports the all above options as commands.

   colorkey
       RGB colorspace color keying.

       The filter accepts the following options:

       color
           The color which will be replaced with transparency.

       similarity
           Similarity percentage with the key color.

           0.01 matches only the exact key color, while 1.0 matches
           everything.

       blend
           Blend percentage.

           0.0 makes pixels either fully transparent, or not transparent at
           all.

           Higher values result in semi-transparent pixels, with a higher
           transparency the more similar the pixels color is to the key color.

       Examples

       o   Make every green pixel in the input image transparent:

                   ffmpeg -i input.png -vf colorkey=green out.png

       o   Overlay a greenscreen-video on top of a static background image.

                   ffmpeg -i background.png -i video.mp4 -filter_complex "[1:v]colorkey=0x3BBD1E:0.3:0.2[ckout];[0:v][ckout]overlay[out]" -map "[out]" output.flv

       Commands

       This filter supports same commands as options.  The command accepts the
       same syntax of the corresponding option.

       If the specified expression is not valid, it is kept at its current
       value.

   colorhold
       Remove all color information for all RGB colors except for certain one.

       The filter accepts the following options:

       color
           The color which will not be replaced with neutral gray.

       similarity
           Similarity percentage with the above color.  0.01 matches only the
           exact key color, while 1.0 matches everything.

       blend
           Blend percentage. 0.0 makes pixels fully gray.  Higher values
           result in more preserved color.

       Commands

       This filter supports same commands as options.  The command accepts the
       same syntax of the corresponding option.

       If the specified expression is not valid, it is kept at its current
       value.

   colorlevels
       Adjust video input frames using levels.

       The filter accepts the following options:

       rimin
       gimin
       bimin
       aimin
           Adjust red, green, blue and alpha input black point.  Allowed
           ranges for options are "[-1.0, 1.0]". Defaults are 0.

       rimax
       gimax
       bimax
       aimax
           Adjust red, green, blue and alpha input white point.  Allowed
           ranges for options are "[-1.0, 1.0]". Defaults are 1.

           Input levels are used to lighten highlights (bright tones), darken
           shadows (dark tones), change the balance of bright and dark tones.

       romin
       gomin
       bomin
       aomin
           Adjust red, green, blue and alpha output black point.  Allowed
           ranges for options are "[0, 1.0]". Defaults are 0.

       romax
       gomax
       bomax
       aomax
           Adjust red, green, blue and alpha output white point.  Allowed
           ranges for options are "[0, 1.0]". Defaults are 1.

           Output levels allows manual selection of a constrained output level
           range.

       Examples

       o   Make video output darker:

                   colorlevels=rimin=0.058:gimin=0.058:bimin=0.058

       o   Increase contrast:

                   colorlevels=rimin=0.039:gimin=0.039:bimin=0.039:rimax=0.96:gimax=0.96:bimax=0.96

       o   Make video output lighter:

                   colorlevels=rimax=0.902:gimax=0.902:bimax=0.902

       o   Increase brightness:

                   colorlevels=romin=0.5:gomin=0.5:bomin=0.5

       Commands

       This filter supports the all above options as commands.

   colormatrix
       Convert color matrix.

       The filter accepts the following options:

       src
       dst Specify the source and destination color matrix. Both values must
           be specified.

           The accepted values are:

           bt709
               BT.709

           fcc FCC

           bt601
               BT.601

           bt470
               BT.470

           bt470bg
               BT.470BG

           smpte170m
               SMPTE-170M

           smpte240m
               SMPTE-240M

           bt2020
               BT.2020

       For example to convert from BT.601 to SMPTE-240M, use the command:

               colormatrix=bt601:smpte240m

   colorspace
       Convert colorspace, transfer characteristics or color primaries.  Input
       video needs to have an even size.

       The filter accepts the following options:

       all Specify all color properties at once.

           The accepted values are:

           bt470m
               BT.470M

           bt470bg
               BT.470BG

           bt601-6-525
               BT.601-6 525

           bt601-6-625
               BT.601-6 625

           bt709
               BT.709

           smpte170m
               SMPTE-170M

           smpte240m
               SMPTE-240M

           bt2020
               BT.2020

       space
           Specify output colorspace.

           The accepted values are:

           bt709
               BT.709

           fcc FCC

           bt470bg
               BT.470BG or BT.601-6 625

           smpte170m
               SMPTE-170M or BT.601-6 525

           smpte240m
               SMPTE-240M

           ycgco
               YCgCo

           bt2020ncl
               BT.2020 with non-constant luminance

       trc Specify output transfer characteristics.

           The accepted values are:

           bt709
               BT.709

           bt470m
               BT.470M

           bt470bg
               BT.470BG

           gamma22
               Constant gamma of 2.2

           gamma28
               Constant gamma of 2.8

           smpte170m
               SMPTE-170M, BT.601-6 625 or BT.601-6 525

           smpte240m
               SMPTE-240M

           srgb
               SRGB

           iec61966-2-1
               iec61966-2-1

           iec61966-2-4
               iec61966-2-4

           xvycc
               xvycc

           bt2020-10
               BT.2020 for 10-bits content

           bt2020-12
               BT.2020 for 12-bits content

       primaries
           Specify output color primaries.

           The accepted values are:

           bt709
               BT.709

           bt470m
               BT.470M

           bt470bg
               BT.470BG or BT.601-6 625

           smpte170m
               SMPTE-170M or BT.601-6 525

           smpte240m
               SMPTE-240M

           film
               film

           smpte431
               SMPTE-431

           smpte432
               SMPTE-432

           bt2020
               BT.2020

           jedec-p22
               JEDEC P22 phosphors

       range
           Specify output color range.

           The accepted values are:

           tv  TV (restricted) range

           mpeg
               MPEG (restricted) range

           pc  PC (full) range

           jpeg
               JPEG (full) range

       format
           Specify output color format.

           The accepted values are:

           yuv420p
               YUV 4:2:0 planar 8-bits

           yuv420p10
               YUV 4:2:0 planar 10-bits

           yuv420p12
               YUV 4:2:0 planar 12-bits

           yuv422p
               YUV 4:2:2 planar 8-bits

           yuv422p10
               YUV 4:2:2 planar 10-bits

           yuv422p12
               YUV 4:2:2 planar 12-bits

           yuv444p
               YUV 4:4:4 planar 8-bits

           yuv444p10
               YUV 4:4:4 planar 10-bits

           yuv444p12
               YUV 4:4:4 planar 12-bits

       fast
           Do a fast conversion, which skips gamma/primary correction. This
           will take significantly less CPU, but will be mathematically
           incorrect. To get output compatible with that produced by the
           colormatrix filter, use fast=1.

       dither
           Specify dithering mode.

           The accepted values are:

           none
               No dithering

           fsb Floyd-Steinberg dithering

       wpadapt
           Whitepoint adaptation mode.

           The accepted values are:

           bradford
               Bradford whitepoint adaptation

           vonkries
               von Kries whitepoint adaptation

           identity
               identity whitepoint adaptation (i.e. no whitepoint adaptation)

       iall
           Override all input properties at once. Same accepted values as all.

       ispace
           Override input colorspace. Same accepted values as space.

       iprimaries
           Override input color primaries. Same accepted values as primaries.

       itrc
           Override input transfer characteristics. Same accepted values as
           trc.

       irange
           Override input color range. Same accepted values as range.

       The filter converts the transfer characteristics, color space and color
       primaries to the specified user values. The output value, if not
       specified, is set to a default value based on the "all" property. If
       that property is also not specified, the filter will log an error. The
       output color range and format default to the same value as the input
       color range and format. The input transfer characteristics, color
       space, color primaries and color range should be set on the input data.
       If any of these are missing, the filter will log an error and no
       conversion will take place.

       For example to convert the input to SMPTE-240M, use the command:

               colorspace=smpte240m

   colortemperature
       Adjust color temperature in video to simulate variations in ambient
       color temperature.

       The filter accepts the following options:

       temperature
           Set the temperature in Kelvin. Allowed range is from 1000 to 40000.
           Default value is 6500 K.

       mix Set mixing with filtered output. Allowed range is from 0 to 1.
           Default value is 1.

       pl  Set the amount of preserving lightness. Allowed range is from 0 to
           1.  Default value is 0.

       Commands

       This filter supports same commands as options.

   convolution
       Apply convolution of 33, 5x5, 7x7 or horizontal/vertical up to 49
       elements.

       The filter accepts the following options:

       0m
       1m
       2m
       3m  Set matrix for each plane.  Matrix is sequence of 9, 25 or 49
           signed integers in square mode, and from 1 to 49 odd number of
           signed integers in row mode.

       0rdiv
       1rdiv
       2rdiv
       3rdiv
           Set multiplier for calculated value for each plane.  If unset or 0,
           it will be sum of all matrix elements.

       0bias
       1bias
       2bias
       3bias
           Set bias for each plane. This value is added to the result of the
           multiplication.  Useful for making the overall image brighter or
           darker. Default is 0.0.

       0mode
       1mode
       2mode
       3mode
           Set matrix mode for each plane. Can be square, row or column.
           Default is square.

       Commands

       This filter supports the all above options as commands.

       Examples

       o   Apply sharpen:

                   convolution="0 -1 0 -1 5 -1 0 -1 0:0 -1 0 -1 5 -1 0 -1 0:0 -1 0 -1 5 -1 0 -1 0:0 -1 0 -1 5 -1 0 -1 0"

       o   Apply blur:

                   convolution="1 1 1 1 1 1 1 1 1:1 1 1 1 1 1 1 1 1:1 1 1 1 1 1 1 1 1:1 1 1 1 1 1 1 1 1:1/9:1/9:1/9:1/9"

       o   Apply edge enhance:

                   convolution="0 0 0 -1 1 0 0 0 0:0 0 0 -1 1 0 0 0 0:0 0 0 -1 1 0 0 0 0:0 0 0 -1 1 0 0 0 0:5:1:1:1:0:128:128:128"

       o   Apply edge detect:

                   convolution="0 1 0 1 -4 1 0 1 0:0 1 0 1 -4 1 0 1 0:0 1 0 1 -4 1 0 1 0:0 1 0 1 -4 1 0 1 0:5:5:5:1:0:128:128:128"

       o   Apply laplacian edge detector which includes diagonals:

                   convolution="1 1 1 1 -8 1 1 1 1:1 1 1 1 -8 1 1 1 1:1 1 1 1 -8 1 1 1 1:1 1 1 1 -8 1 1 1 1:5:5:5:1:0:128:128:0"

       o   Apply emboss:

                   convolution="-2 -1 0 -1 1 1 0 1 2:-2 -1 0 -1 1 1 0 1 2:-2 -1 0 -1 1 1 0 1 2:-2 -1 0 -1 1 1 0 1 2"

   convolve
       Apply 2D convolution of video stream in frequency domain using second
       stream as impulse.

       The filter accepts the following options:

       planes
           Set which planes to process.

       impulse
           Set which impulse video frames will be processed, can be first or
           all. Default is all.

       The "convolve" filter also supports the framesync options.

   copy
       Copy the input video source unchanged to the output. This is mainly
       useful for testing purposes.

   coreimage
       Video filtering on GPU using Apple's CoreImage API on OSX.

       Hardware acceleration is based on an OpenGL context. Usually, this
       means it is processed by video hardware. However, software-based OpenGL
       implementations exist which means there is no guarantee for hardware
       processing. It depends on the respective OSX.

       There are many filters and image generators provided by Apple that come
       with a large variety of options. The filter has to be referenced by its
       name along with its options.

       The coreimage filter accepts the following options:

       list_filters
           List all available filters and generators along with all their
           respective options as well as possible minimum and maximum values
           along with the default values.

                   list_filters=true

       filter
           Specify all filters by their respective name and options.  Use
           list_filters to determine all valid filter names and options.
           Numerical options are specified by a float value and are
           automatically clamped to their respective value range.  Vector and
           color options have to be specified by a list of space separated
           float values. Character escaping has to be done.  A special option
           name "default" is available to use default options for a filter.

           It is required to specify either "default" or at least one of the
           filter options.  All omitted options are used with their default
           values.  The syntax of the filter string is as follows:

                   filter=<NAME>@<OPTION>=<VALUE>[@<OPTION>=<VALUE>][@...][#<NAME>@<OPTION>=<VALUE>[@<OPTION>=<VALUE>][@...]][#...]

       output_rect
           Specify a rectangle where the output of the filter chain is copied
           into the input image. It is given by a list of space separated
           float values:

                   output_rect=x\ y\ width\ height

           If not given, the output rectangle equals the dimensions of the
           input image.  The output rectangle is automatically cropped at the
           borders of the input image. Negative values are valid for each
           component.

                   output_rect=25\ 25\ 100\ 100

       Several filters can be chained for successive processing without GPU-
       HOST transfers allowing for fast processing of complex filter chains.
       Currently, only filters with zero (generators) or exactly one (filters)
       input image and one output image are supported. Also, transition
       filters are not yet usable as intended.

       Some filters generate output images with additional padding depending
       on the respective filter kernel. The padding is automatically removed
       to ensure the filter output has the same size as the input image.

       For image generators, the size of the output image is determined by the
       previous output image of the filter chain or the input image of the
       whole filterchain, respectively. The generators do not use the pixel
       information of this image to generate their output. However, the
       generated output is blended onto this image, resulting in partial or
       complete coverage of the output image.

       The coreimagesrc video source can be used for generating input images
       which are directly fed into the filter chain. By using it, providing
       input images by another video source or an input video is not required.

       Examples

       o   List all filters available:

                   coreimage=list_filters=true

       o   Use the CIBoxBlur filter with default options to blur an image:

                   coreimage=filter=CIBoxBlur@default

       o   Use a filter chain with CISepiaTone at default values and
           CIVignetteEffect with its center at 100x100 and a radius of 50
           pixels:

                   coreimage=filter=CIBoxBlur@default#CIVignetteEffect@inputCenter=100\ 100@inputRadius=50

       o   Use nullsrc and CIQRCodeGenerator to create a QR code for the
           FFmpeg homepage, given as complete and escaped command-line for
           Apple's standard bash shell:

                   ffmpeg -f lavfi -i nullsrc=s=100x100,coreimage=filter=CIQRCodeGenerator@inputMessage=https\\\\\://FFmpeg.org/@inputCorrectionLevel=H -frames:v 1 QRCode.png

   cover_rect
       Cover a rectangular object

       It accepts the following options:

       cover
           Filepath of the optional cover image, needs to be in yuv420.

       mode
           Set covering mode.

           It accepts the following values:

           cover
               cover it by the supplied image

           blur
               cover it by interpolating the surrounding pixels

           Default value is blur.

       Examples

       o   Cover a rectangular object by the supplied image of a given video
           using ffmpeg:

                   ffmpeg -i file.ts -vf find_rect=newref.pgm,cover_rect=cover.jpg:mode=cover new.mkv

   crop
       Crop the input video to given dimensions.

       It accepts the following parameters:

       w, out_w
           The width of the output video. It defaults to "iw".  This
           expression is evaluated only once during the filter configuration,
           or when the w or out_w command is sent.

       h, out_h
           The height of the output video. It defaults to "ih".  This
           expression is evaluated only once during the filter configuration,
           or when the h or out_h command is sent.

       x   The horizontal position, in the input video, of the left edge of
           the output video. It defaults to "(in_w-out_w)/2".  This expression
           is evaluated per-frame.

       y   The vertical position, in the input video, of the top edge of the
           output video.  It defaults to "(in_h-out_h)/2".  This expression is
           evaluated per-frame.

       keep_aspect
           If set to 1 will force the output display aspect ratio to be the
           same of the input, by changing the output sample aspect ratio. It
           defaults to 0.

       exact
           Enable exact cropping. If enabled, subsampled videos will be
           cropped at exact width/height/x/y as specified and will not be
           rounded to nearest smaller value.  It defaults to 0.

       The out_w, out_h, x, y parameters are expressions containing the
       following constants:

       x
       y   The computed values for x and y. They are evaluated for each new
           frame.

       in_w
       in_h
           The input width and height.

       iw
       ih  These are the same as in_w and in_h.

       out_w
       out_h
           The output (cropped) width and height.

       ow
       oh  These are the same as out_w and out_h.

       a   same as iw / ih

       sar input sample aspect ratio

       dar input display aspect ratio, it is the same as (iw / ih) * sar

       hsub
       vsub
           horizontal and vertical chroma subsample values. For example for
           the pixel format "yuv422p" hsub is 2 and vsub is 1.

       n   The number of the input frame, starting from 0.

       pos the position in the file of the input frame, NAN if unknown

       t   The timestamp expressed in seconds. It's NAN if the input timestamp
           is unknown.

       The expression for out_w may depend on the value of out_h, and the
       expression for out_h may depend on out_w, but they cannot depend on x
       and y, as x and y are evaluated after out_w and out_h.

       The x and y parameters specify the expressions for the position of the
       top-left corner of the output (non-cropped) area. They are evaluated
       for each frame. If the evaluated value is not valid, it is approximated
       to the nearest valid value.

       The expression for x may depend on y, and the expression for y may
       depend on x.

       Examples

       o   Crop area with size 100x100 at position (12,34).

                   crop=100:100:12:34

           Using named options, the example above becomes:

                   crop=w=100:h=100:x=12:y=34

       o   Crop the central input area with size 100x100:

                   crop=100:100

       o   Crop the central input area with size 2/3 of the input video:

                   crop=2/3*in_w:2/3*in_h

       o   Crop the input video central square:

                   crop=out_w=in_h
                   crop=in_h

       o   Delimit the rectangle with the top-left corner placed at position
           100:100 and the right-bottom corner corresponding to the right-
           bottom corner of the input image.

                   crop=in_w-100:in_h-100:100:100

       o   Crop 10 pixels from the left and right borders, and 20 pixels from
           the top and bottom borders

                   crop=in_w-2*10:in_h-2*20

       o   Keep only the bottom right quarter of the input image:

                   crop=in_w/2:in_h/2:in_w/2:in_h/2

       o   Crop height for getting Greek harmony:

                   crop=in_w:1/PHI*in_w

       o   Apply trembling effect:

                   crop=in_w/2:in_h/2:(in_w-out_w)/2+((in_w-out_w)/2)*sin(n/10):(in_h-out_h)/2 +((in_h-out_h)/2)*sin(n/7)

       o   Apply erratic camera effect depending on timestamp:

                   crop=in_w/2:in_h/2:(in_w-out_w)/2+((in_w-out_w)/2)*sin(t*10):(in_h-out_h)/2 +((in_h-out_h)/2)*sin(t*13)"

       o   Set x depending on the value of y:

                   crop=in_w/2:in_h/2:y:10+10*sin(n/10)

       Commands

       This filter supports the following commands:

       w, out_w
       h, out_h
       x
       y   Set width/height of the output video and the horizontal/vertical
           position in the input video.  The command accepts the same syntax
           of the corresponding option.

           If the specified expression is not valid, it is kept at its current
           value.

   cropdetect
       Auto-detect the crop size.

       It calculates the necessary cropping parameters and prints the
       recommended parameters via the logging system. The detected dimensions
       correspond to the non-black area of the input video.

       It accepts the following parameters:

       limit
           Set higher black value threshold, which can be optionally specified
           from nothing (0) to everything (255 for 8-bit based formats). An
           intensity value greater to the set value is considered non-black.
           It defaults to 24.  You can also specify a value between 0.0 and
           1.0 which will be scaled depending on the bitdepth of the pixel
           format.

       round
           The value which the width/height should be divisible by. It
           defaults to 16. The offset is automatically adjusted to center the
           video. Use 2 to get only even dimensions (needed for 4:2:2 video).
           16 is best when encoding to most video codecs.

       skip
           Set the number of initial frames for which evaluation is skipped.
           Default is 2. Range is 0 to INT_MAX.

       reset_count, reset
           Set the counter that determines after how many frames cropdetect
           will reset the previously detected largest video area and start
           over to detect the current optimal crop area. Default value is 0.

           This can be useful when channel logos distort the video area. 0
           indicates 'never reset', and returns the largest area encountered
           during playback.

   cue
       Delay video filtering until a given wallclock timestamp. The filter
       first passes on preroll amount of frames, then it buffers at most
       buffer amount of frames and waits for the cue. After reaching the cue
       it forwards the buffered frames and also any subsequent frames coming
       in its input.

       The filter can be used synchronize the output of multiple ffmpeg
       processes for realtime output devices like decklink. By putting the
       delay in the filtering chain and pre-buffering frames the process can
       pass on data to output almost immediately after the target wallclock
       timestamp is reached.

       Perfect frame accuracy cannot be guaranteed, but the result is good
       enough for some use cases.

       cue The cue timestamp expressed in a UNIX timestamp in microseconds.
           Default is 0.

       preroll
           The duration of content to pass on as preroll expressed in seconds.
           Default is 0.

       buffer
           The maximum duration of content to buffer before waiting for the
           cue expressed in seconds. Default is 0.

   curves
       Apply color adjustments using curves.

       This filter is similar to the Adobe Photoshop and GIMP curves tools.
       Each component (red, green and blue) has its values defined by N key
       points tied from each other using a smooth curve. The x-axis represents
       the pixel values from the input frame, and the y-axis the new pixel
       values to be set for the output frame.

       By default, a component curve is defined by the two points (0;0) and
       (1;1). This creates a straight line where each original pixel value is
       "adjusted" to its own value, which means no change to the image.

       The filter allows you to redefine these two points and add some more. A
       new curve (using a natural cubic spline interpolation) will be define
       to pass smoothly through all these new coordinates. The new defined
       points needs to be strictly increasing over the x-axis, and their x and
       y values must be in the [0;1] interval.  If the computed curves
       happened to go outside the vector spaces, the values will be clipped
       accordingly.

       The filter accepts the following options:

       preset
           Select one of the available color presets. This option can be used
           in addition to the r, g, b parameters; in this case, the later
           options takes priority on the preset values.  Available presets
           are:

           none
           color_negative
           cross_process
           darker
           increase_contrast
           lighter
           linear_contrast
           medium_contrast
           negative
           strong_contrast
           vintage

           Default is "none".

       master, m
           Set the master key points. These points will define a second pass
           mapping. It is sometimes called a "luminance" or "value" mapping.
           It can be used with r, g, b or all since it acts like a post-
           processing LUT.

       red, r
           Set the key points for the red component.

       green, g
           Set the key points for the green component.

       blue, b
           Set the key points for the blue component.

       all Set the key points for all components (not including master).  Can
           be used in addition to the other key points component options. In
           this case, the unset component(s) will fallback on this all
           setting.

       psfile
           Specify a Photoshop curves file (".acv") to import the settings
           from.

       plot
           Save Gnuplot script of the curves in specified file.

       To avoid some filtergraph syntax conflicts, each key points list need
       to be defined using the following syntax: "x0/y0 x1/y1 x2/y2 ...".

       Commands

       This filter supports same commands as options.

       Examples

       o   Increase slightly the middle level of blue:

                   curves=blue='0/0 0.5/0.58 1/1'

       o   Vintage effect:

                   curves=r='0/0.11 .42/.51 1/0.95':g='0/0 0.50/0.48 1/1':b='0/0.22 .49/.44 1/0.8'

           Here we obtain the following coordinates for each components:

           red "(0;0.11) (0.42;0.51) (1;0.95)"

           green
               "(0;0) (0.50;0.48) (1;1)"

           blue
               "(0;0.22) (0.49;0.44) (1;0.80)"

       o   The previous example can also be achieved with the associated
           built-in preset:

                   curves=preset=vintage

       o   Or simply:

                   curves=vintage

       o   Use a Photoshop preset and redefine the points of the green
           component:

                   curves=psfile='MyCurvesPresets/purple.acv':green='0/0 0.45/0.53 1/1'

       o   Check out the curves of the "cross_process" profile using ffmpeg
           and gnuplot:

                   ffmpeg -f lavfi -i color -vf curves=cross_process:plot=/tmp/curves.plt -frames:v 1 -f null -
                   gnuplot -p /tmp/curves.plt

   datascope
       Video data analysis filter.

       This filter shows hexadecimal pixel values of part of video.

       The filter accepts the following options:

       size, s
           Set output video size.

       x   Set x offset from where to pick pixels.

       y   Set y offset from where to pick pixels.

       mode
           Set scope mode, can be one of the following:

           mono
               Draw hexadecimal pixel values with white color on black
               background.

           color
               Draw hexadecimal pixel values with input video pixel color on
               black background.

           color2
               Draw hexadecimal pixel values on color background picked from
               input video, the text color is picked in such way so its always
               visible.

       axis
           Draw rows and columns numbers on left and top of video.

       opacity
           Set background opacity.

       format
           Set display number format. Can be "hex", or "dec". Default is
           "hex".

       components
           Set pixel components to display. By default all pixel components
           are displayed.

       Commands

       This filter supports same commands as options excluding "size" option.

   dblur
       Apply Directional blur filter.

       The filter accepts the following options:

       angle
           Set angle of directional blur. Default is 45.

       radius
           Set radius of directional blur. Default is 5.

       planes
           Set which planes to filter. By default all planes are filtered.

       Commands

       This filter supports same commands as options.  The command accepts the
       same syntax of the corresponding option.

       If the specified expression is not valid, it is kept at its current
       value.

   dctdnoiz
       Denoise frames using 2D DCT (frequency domain filtering).

       This filter is not designed for real time.

       The filter accepts the following options:

       sigma, s
           Set the noise sigma constant.

           This sigma defines a hard threshold of "3 * sigma"; every DCT
           coefficient (absolute value) below this threshold with be dropped.

           If you need a more advanced filtering, see expr.

           Default is 0.

       overlap
           Set number overlapping pixels for each block. Since the filter can
           be slow, you may want to reduce this value, at the cost of a less
           effective filter and the risk of various artefacts.

           If the overlapping value doesn't permit processing the whole input
           width or height, a warning will be displayed and according borders
           won't be denoised.

           Default value is blocksize-1, which is the best possible setting.

       expr, e
           Set the coefficient factor expression.

           For each coefficient of a DCT block, this expression will be
           evaluated as a multiplier value for the coefficient.

           If this is option is set, the sigma option will be ignored.

           The absolute value of the coefficient can be accessed through the c
           variable.

       n   Set the blocksize using the number of bits. "1<<n" defines the
           blocksize, which is the width and height of the processed blocks.

           The default value is 3 (8x8) and can be raised to 4 for a blocksize
           of 16x16. Note that changing this setting has huge consequences on
           the speed processing. Also, a larger block size does not
           necessarily means a better de-noising.

       Examples

       Apply a denoise with a sigma of 4.5:

               dctdnoiz=4.5

       The same operation can be achieved using the expression system:

               dctdnoiz=e='gte(c, 4.5*3)'

       Violent denoise using a block size of "16x16":

               dctdnoiz=15:n=4

   deband
       Remove banding artifacts from input video.  It works by replacing
       banded pixels with average value of referenced pixels.

       The filter accepts the following options:

       1thr
       2thr
       3thr
       4thr
           Set banding detection threshold for each plane. Default is 0.02.
           Valid range is 0.00003 to 0.5.  If difference between current pixel
           and reference pixel is less than threshold, it will be considered
           as banded.

       range, r
           Banding detection range in pixels. Default is 16. If positive,
           random number in range 0 to set value will be used. If negative,
           exact absolute value will be used.  The range defines square of
           four pixels around current pixel.

       direction, d
           Set direction in radians from which four pixel will be compared. If
           positive, random direction from 0 to set direction will be picked.
           If negative, exact of absolute value will be picked. For example
           direction 0, -PI or -2*PI radians will pick only pixels on same row
           and -PI/2 will pick only pixels on same column.

       blur, b
           If enabled, current pixel is compared with average value of all
           four surrounding pixels. The default is enabled. If disabled
           current pixel is compared with all four surrounding pixels. The
           pixel is considered banded if only all four differences with
           surrounding pixels are less than threshold.

       coupling, c
           If enabled, current pixel is changed if and only if all pixel
           components are banded, e.g. banding detection threshold is
           triggered for all color components.  The default is disabled.

       Commands

       This filter supports the all above options as commands.

   deblock
       Remove blocking artifacts from input video.

       The filter accepts the following options:

       filter
           Set filter type, can be weak or strong. Default is strong.  This
           controls what kind of deblocking is applied.

       block
           Set size of block, allowed range is from 4 to 512. Default is 8.

       alpha
       beta
       gamma
       delta
           Set blocking detection thresholds. Allowed range is 0 to 1.
           Defaults are: 0.098 for alpha and 0.05 for the rest.  Using higher
           threshold gives more deblocking strength.  Setting alpha controls
           threshold detection at exact edge of block.  Remaining options
           controls threshold detection near the edge. Each one for
           below/above or left/right. Setting any of those to 0 disables
           deblocking.

       planes
           Set planes to filter. Default is to filter all available planes.

       Examples

       o   Deblock using weak filter and block size of 4 pixels.

                   deblock=filter=weak:block=4

       o   Deblock using strong filter, block size of 4 pixels and custom
           thresholds for deblocking more edges.

                   deblock=filter=strong:block=4:alpha=0.12:beta=0.07:gamma=0.06:delta=0.05

       o   Similar as above, but filter only first plane.

                   deblock=filter=strong:block=4:alpha=0.12:beta=0.07:gamma=0.06:delta=0.05:planes=1

       o   Similar as above, but filter only second and third plane.

                   deblock=filter=strong:block=4:alpha=0.12:beta=0.07:gamma=0.06:delta=0.05:planes=6

       Commands

       This filter supports the all above options as commands.

   decimate
       Drop duplicated frames at regular intervals.

       The filter accepts the following options:

       cycle
           Set the number of frames from which one will be dropped. Setting
           this to N means one frame in every batch of N frames will be
           dropped.  Default is 5.

       dupthresh
           Set the threshold for duplicate detection. If the difference metric
           for a frame is less than or equal to this value, then it is
           declared as duplicate. Default is 1.1

       scthresh
           Set scene change threshold. Default is 15.

       blockx
       blocky
           Set the size of the x and y-axis blocks used during metric
           calculations.  Larger blocks give better noise suppression, but
           also give worse detection of small movements. Must be a power of
           two. Default is 32.

       ppsrc
           Mark main input as a pre-processed input and activate clean source
           input stream. This allows the input to be pre-processed with
           various filters to help the metrics calculation while keeping the
           frame selection lossless. When set to 1, the first stream is for
           the pre-processed input, and the second stream is the clean source
           from where the kept frames are chosen. Default is 0.

       chroma
           Set whether or not chroma is considered in the metric calculations.
           Default is 1.

   deconvolve
       Apply 2D deconvolution of video stream in frequency domain using second
       stream as impulse.

       The filter accepts the following options:

       planes
           Set which planes to process.

       impulse
           Set which impulse video frames will be processed, can be first or
           all. Default is all.

       noise
           Set noise when doing divisions. Default is 0.0000001. Useful when
           width and height are not same and not power of 2 or if stream prior
           to convolving had noise.

       The "deconvolve" filter also supports the framesync options.

   dedot
       Reduce cross-luminance (dot-crawl) and cross-color (rainbows) from
       video.

       It accepts the following options:

       m   Set mode of operation. Can be combination of dotcrawl for cross-
           luminance reduction and/or rainbows for cross-color reduction.

       lt  Set spatial luma threshold. Lower values increases reduction of
           cross-luminance.

       tl  Set tolerance for temporal luma. Higher values increases reduction
           of cross-luminance.

       tc  Set tolerance for chroma temporal variation. Higher values
           increases reduction of cross-color.

       ct  Set temporal chroma threshold. Lower values increases reduction of
           cross-color.

   deflate
       Apply deflate effect to the video.

       This filter replaces the pixel by the local(33) average by taking into
       account only values lower than the pixel.

       It accepts the following options:

       threshold0
       threshold1
       threshold2
       threshold3
           Limit the maximum change for each plane, default is 65535.  If 0,
           plane will remain unchanged.

       Commands

       This filter supports the all above options as commands.

   deflicker
       Remove temporal frame luminance variations.

       It accepts the following options:

       size, s
           Set moving-average filter size in frames. Default is 5. Allowed
           range is 2 - 129.

       mode, m
           Set averaging mode to smooth temporal luminance variations.

           Available values are:

           am  Arithmetic mean

           gm  Geometric mean

           hm  Harmonic mean

           qm  Quadratic mean

           cm  Cubic mean

           pm  Power mean

           median
               Median

       bypass
           Do not actually modify frame. Useful when one only wants metadata.

   dejudder
       Remove judder produced by partially interlaced telecined content.

       Judder can be introduced, for instance, by pullup filter. If the
       original source was partially telecined content then the output of
       "pullup,dejudder" will have a variable frame rate. May change the
       recorded frame rate of the container. Aside from that change, this
       filter will not affect constant frame rate video.

       The option available in this filter is:

       cycle
           Specify the length of the window over which the judder repeats.

           Accepts any integer greater than 1. Useful values are:

           4   If the original was telecined from 24 to 30 fps (Film to NTSC).

           5   If the original was telecined from 25 to 30 fps (PAL to NTSC).

           20  If a mixture of the two.

           The default is 4.

   delogo
       Suppress a TV station logo by a simple interpolation of the surrounding
       pixels. Just set a rectangle covering the logo and watch it disappear
       (and sometimes something even uglier appear - your mileage may vary).

       It accepts the following parameters:

       x
       y   Specify the top left corner coordinates of the logo. They must be
           specified.

       w
       h   Specify the width and height of the logo to clear. They must be
           specified.

       show
           When set to 1, a green rectangle is drawn on the screen to simplify
           finding the right x, y, w, and h parameters.  The default value is
           0.

           The rectangle is drawn on the outermost pixels which will be
           (partly) replaced with interpolated values. The values of the next
           pixels immediately outside this rectangle in each direction will be
           used to compute the interpolated pixel values inside the rectangle.

       Examples

       o   Set a rectangle covering the area with top left corner coordinates
           0,0 and size 100x77:

                   delogo=x=0:y=0:w=100:h=77

   derain
       Remove the rain in the input image/video by applying the derain methods
       based on convolutional neural networks. Supported models:

       o   Recurrent Squeeze-and-Excitation Context Aggregation Net (RESCAN).
           See
           <http://openaccess.thecvf.com/content_ECCV_2018/papers/Xia_Li_Recurrent_Squeeze-and-Excitation_Context_ECCV_2018_paper.pdf>.

       Training as well as model generation scripts are provided in the
       repository at <https://github.com/XueweiMeng/derain_filter.git<>.

       Native model files (.model) can be generated from TensorFlow model
       files (.pb) by using tools/python/convert.py

       The filter accepts the following options:

       filter_type
           Specify which filter to use. This option accepts the following
           values:

           derain
               Derain filter. To conduct derain filter, you need to use a
               derain model.

           dehaze
               Dehaze filter. To conduct dehaze filter, you need to use a
               dehaze model.

           Default value is derain.

       dnn_backend
           Specify which DNN backend to use for model loading and execution.
           This option accepts the following values:

           native
               Native implementation of DNN loading and execution.

           tensorflow
               TensorFlow backend. To enable this backend you need to install
               the TensorFlow for C library (see
               <https://www.tensorflow.org/install/install_c>) and configure
               FFmpeg with "--enable-libtensorflow"

           Default value is native.

       model
           Set path to model file specifying network architecture and its
           parameters.  Note that different backends use different file
           formats. TensorFlow and native backend can load files for only its
           format.

       It can also be finished with dnn_processing filter.

   deshake
       Attempt to fix small changes in horizontal and/or vertical shift. This
       filter helps remove camera shake from hand-holding a camera, bumping a
       tripod, moving on a vehicle, etc.

       The filter accepts the following options:

       x
       y
       w
       h   Specify a rectangular area where to limit the search for motion
           vectors.  If desired the search for motion vectors can be limited
           to a rectangular area of the frame defined by its top left corner,
           width and height. These parameters have the same meaning as the
           drawbox filter which can be used to visualise the position of the
           bounding box.

           This is useful when simultaneous movement of subjects within the
           frame might be confused for camera motion by the motion vector
           search.

           If any or all of x, y, w and h are set to -1 then the full frame is
           used. This allows later options to be set without specifying the
           bounding box for the motion vector search.

           Default - search the whole frame.

       rx
       ry  Specify the maximum extent of movement in x and y directions in the
           range 0-64 pixels. Default 16.

       edge
           Specify how to generate pixels to fill blanks at the edge of the
           frame. Available values are:

           blank, 0
               Fill zeroes at blank locations

           original, 1
               Original image at blank locations

           clamp, 2
               Extruded edge value at blank locations

           mirror, 3
               Mirrored edge at blank locations

           Default value is mirror.

       blocksize
           Specify the blocksize to use for motion search. Range 4-128 pixels,
           default 8.

       contrast
           Specify the contrast threshold for blocks. Only blocks with more
           than the specified contrast (difference between darkest and
           lightest pixels) will be considered. Range 1-255, default 125.

       search
           Specify the search strategy. Available values are:

           exhaustive, 0
               Set exhaustive search

           less, 1
               Set less exhaustive search.

           Default value is exhaustive.

       filename
           If set then a detailed log of the motion search is written to the
           specified file.

   despill
       Remove unwanted contamination of foreground colors, caused by reflected
       color of greenscreen or bluescreen.

       This filter accepts the following options:

       type
           Set what type of despill to use.

       mix Set how spillmap will be generated.

       expand
           Set how much to get rid of still remaining spill.

       red Controls amount of red in spill area.

       green
           Controls amount of green in spill area.  Should be -1 for
           greenscreen.

       blue
           Controls amount of blue in spill area.  Should be -1 for
           bluescreen.

       brightness
           Controls brightness of spill area, preserving colors.

       alpha
           Modify alpha from generated spillmap.

       Commands

       This filter supports the all above options as commands.

   detelecine
       Apply an exact inverse of the telecine operation. It requires a
       predefined pattern specified using the pattern option which must be the
       same as that passed to the telecine filter.

       This filter accepts the following options:

       first_field
           top, t
               top field first

           bottom, b
               bottom field first The default value is "top".

       pattern
           A string of numbers representing the pulldown pattern you wish to
           apply.  The default value is 23.

       start_frame
           A number representing position of the first frame with respect to
           the telecine pattern. This is to be used if the stream is cut. The
           default value is 0.

   dilation
       Apply dilation effect to the video.

       This filter replaces the pixel by the local(33) maximum.

       It accepts the following options:

       threshold0
       threshold1
       threshold2
       threshold3
           Limit the maximum change for each plane, default is 65535.  If 0,
           plane will remain unchanged.

       coordinates
           Flag which specifies the pixel to refer to. Default is 255 i.e. all
           eight pixels are used.

           Flags to local 33 coordinates maps like this:

               1 2 3
               4   5
               6 7 8

       Commands

       This filter supports the all above options as commands.

   displace
       Displace pixels as indicated by second and third input stream.

       It takes three input streams and outputs one stream, the first input is
       the source, and second and third input are displacement maps.

       The second input specifies how much to displace pixels along the
       x-axis, while the third input specifies how much to displace pixels
       along the y-axis.  If one of displacement map streams terminates, last
       frame from that displacement map will be used.

       Note that once generated, displacements maps can be reused over and
       over again.

       A description of the accepted options follows.

       edge
           Set displace behavior for pixels that are out of range.

           Available values are:

           blank
               Missing pixels are replaced by black pixels.

           smear
               Adjacent pixels will spread out to replace missing pixels.

           wrap
               Out of range pixels are wrapped so they point to pixels of
               other side.

           mirror
               Out of range pixels will be replaced with mirrored pixels.

           Default is smear.

       Examples

       o   Add ripple effect to rgb input of video size hd720:

                   ffmpeg -i INPUT -f lavfi -i nullsrc=s=hd720,lutrgb=128:128:128 -f lavfi -i nullsrc=s=hd720,geq='r=128+30*sin(2*PI*X/400+T):g=128+30*sin(2*PI*X/400+T):b=128+30*sin(2*PI*X/400+T)' -lavfi '[0][1][2]displace' OUTPUT

       o   Add wave effect to rgb input of video size hd720:

                   ffmpeg -i INPUT -f lavfi -i nullsrc=hd720,geq='r=128+80*(sin(sqrt((X-W/2)*(X-W/2)+(Y-H/2)*(Y-H/2))/220*2*PI+T)):g=128+80*(sin(sqrt((X-W/2)*(X-W/2)+(Y-H/2)*(Y-H/2))/220*2*PI+T)):b=128+80*(sin(sqrt((X-W/2)*(X-W/2)+(Y-H/2)*(Y-H/2))/220*2*PI+T))' -lavfi '[1]split[x][y],[0][x][y]displace' OUTPUT

   dnn_processing
       Do image processing with deep neural networks. It works together with
       another filter which converts the pixel format of the Frame to what the
       dnn network requires.

       The filter accepts the following options:

       dnn_backend
           Specify which DNN backend to use for model loading and execution.
           This option accepts the following values:

           native
               Native implementation of DNN loading and execution.

           tensorflow
               TensorFlow backend. To enable this backend you need to install
               the TensorFlow for C library (see
               <https://www.tensorflow.org/install/install_c>) and configure
               FFmpeg with "--enable-libtensorflow"

           openvino
               OpenVINO backend. To enable this backend you need to build and
               install the OpenVINO for C library (see
               <https://github.com/openvinotoolkit/openvino/blob/master/build-instruction.md>)
               and configure FFmpeg with "--enable-libopenvino"
               (--extra-cflags=-I... --extra-ldflags=-L... might be needed if
               the header files and libraries are not installed into system
               path)

           Default value is native.

       model
           Set path to model file specifying network architecture and its
           parameters.  Note that different backends use different file
           formats. TensorFlow, OpenVINO and native backend can load files for
           only its format.

           Native model file (.model) can be generated from TensorFlow model
           file (.pb) by using tools/python/convert.py

       input
           Set the input name of the dnn network.

       output
           Set the output name of the dnn network.

       async
           use DNN async execution if set (default: set), roll back to sync
           execution if the backend does not support async.

       Examples

       o   Remove rain in rgb24 frame with can.pb (see derain filter):

                   ./ffmpeg -i rain.jpg -vf format=rgb24,dnn_processing=dnn_backend=tensorflow:model=can.pb:input=x:output=y derain.jpg

       o   Halve the pixel value of the frame with format gray32f:

                   ffmpeg -i input.jpg -vf format=grayf32,dnn_processing=model=halve_gray_float.model:input=dnn_in:output=dnn_out:dnn_backend=native -y out.native.png

       o   Handle the Y channel with srcnn.pb (see sr filter) for frame with
           yuv420p (planar YUV formats supported):

                   ./ffmpeg -i 480p.jpg -vf format=yuv420p,scale=w=iw*2:h=ih*2,dnn_processing=dnn_backend=tensorflow:model=srcnn.pb:input=x:output=y -y srcnn.jpg

       o   Handle the Y channel with espcn.pb (see sr filter), which changes
           frame size, for format yuv420p (planar YUV formats supported):

                   ./ffmpeg -i 480p.jpg -vf format=yuv420p,dnn_processing=dnn_backend=tensorflow:model=espcn.pb:input=x:output=y -y tmp.espcn.jpg

   drawbox
       Draw a colored box on the input image.

       It accepts the following parameters:

       x
       y   The expressions which specify the top left corner coordinates of
           the box. It defaults to 0.

       width, w
       height, h
           The expressions which specify the width and height of the box; if 0
           they are interpreted as the input width and height. It defaults to
           0.

       color, c
           Specify the color of the box to write. For the general syntax of
           this option, check the "Color" section in the ffmpeg-utils manual.
           If the special value "invert" is used, the box edge color is the
           same as the video with inverted luma.

       thickness, t
           The expression which sets the thickness of the box edge.  A value
           of "fill" will create a filled box. Default value is 3.

           See below for the list of accepted constants.

       replace
           Applicable if the input has alpha. With value 1, the pixels of the
           painted box will overwrite the video's color and alpha pixels.
           Default is 0, which composites the box onto the input, leaving the
           video's alpha intact.

       The parameters for x, y, w and h and t are expressions containing the
       following constants:

       dar The input display aspect ratio, it is the same as (w / h) * sar.

       hsub
       vsub
           horizontal and vertical chroma subsample values. For example for
           the pixel format "yuv422p" hsub is 2 and vsub is 1.

       in_h, ih
       in_w, iw
           The input width and height.

       sar The input sample aspect ratio.

       x
       y   The x and y offset coordinates where the box is drawn.

       w
       h   The width and height of the drawn box.

       t   The thickness of the drawn box.

           These constants allow the x, y, w, h and t expressions to refer to
           each other, so you may for example specify "y=x/dar" or "h=w/dar".

       Examples

       o   Draw a black box around the edge of the input image:

                   drawbox

       o   Draw a box with color red and an opacity of 50%:

                   drawbox=10:20:200:60:red@0.5

           The previous example can be specified as:

                   drawbox=x=10:y=20:w=200:h=60:color=red@0.5

       o   Fill the box with pink color:

                   drawbox=x=10:y=10:w=100:h=100:color=pink@0.5:t=fill

       o   Draw a 2-pixel red 2.40:1 mask:

                   drawbox=x=-t:y=0.5*(ih-iw/2.4)-t:w=iw+t*2:h=iw/2.4+t*2:t=2:c=red

       Commands

       This filter supports same commands as options.  The command accepts the
       same syntax of the corresponding option.

       If the specified expression is not valid, it is kept at its current
       value.

   drawgraph
       Draw a graph using input video metadata.

       It accepts the following parameters:

       m1  Set 1st frame metadata key from which metadata values will be used
           to draw a graph.

       fg1 Set 1st foreground color expression.

       m2  Set 2nd frame metadata key from which metadata values will be used
           to draw a graph.

       fg2 Set 2nd foreground color expression.

       m3  Set 3rd frame metadata key from which metadata values will be used
           to draw a graph.

       fg3 Set 3rd foreground color expression.

       m4  Set 4th frame metadata key from which metadata values will be used
           to draw a graph.

       fg4 Set 4th foreground color expression.

       min Set minimal value of metadata value.

       max Set maximal value of metadata value.

       bg  Set graph background color. Default is white.

       mode
           Set graph mode.

           Available values for mode is:

           bar
           dot
           line

           Default is "line".

       slide
           Set slide mode.

           Available values for slide is:

           frame
               Draw new frame when right border is reached.

           replace
               Replace old columns with new ones.

           scroll
               Scroll from right to left.

           rscroll
               Scroll from left to right.

           picture
               Draw single picture.

           Default is "frame".

       size
           Set size of graph video. For the syntax of this option, check the
           "Video size" section in the ffmpeg-utils manual.  The default value
           is "900x256".

       rate, r
           Set the output frame rate. Default value is 25.

           The foreground color expressions can use the following variables:

           MIN Minimal value of metadata value.

           MAX Maximal value of metadata value.

           VAL Current metadata key value.

           The color is defined as 0xAABBGGRR.

       Example using metadata from signalstats filter:

               signalstats,drawgraph=lavfi.signalstats.YAVG:min=0:max=255

       Example using metadata from ebur128 filter:

               ebur128=metadata=1,adrawgraph=lavfi.r128.M:min=-120:max=5

   drawgrid
       Draw a grid on the input image.

       It accepts the following parameters:

       x
       y   The expressions which specify the coordinates of some point of grid
           intersection (meant to configure offset). Both default to 0.

       width, w
       height, h
           The expressions which specify the width and height of the grid
           cell, if 0 they are interpreted as the input width and height,
           respectively, minus "thickness", so image gets framed. Default to
           0.

       color, c
           Specify the color of the grid. For the general syntax of this
           option, check the "Color" section in the ffmpeg-utils manual. If
           the special value "invert" is used, the grid color is the same as
           the video with inverted luma.

       thickness, t
           The expression which sets the thickness of the grid line. Default
           value is 1.

           See below for the list of accepted constants.

       replace
           Applicable if the input has alpha. With 1 the pixels of the painted
           grid will overwrite the video's color and alpha pixels.  Default is
           0, which composites the grid onto the input, leaving the video's
           alpha intact.

       The parameters for x, y, w and h and t are expressions containing the
       following constants:

       dar The input display aspect ratio, it is the same as (w / h) * sar.

       hsub
       vsub
           horizontal and vertical chroma subsample values. For example for
           the pixel format "yuv422p" hsub is 2 and vsub is 1.

       in_h, ih
       in_w, iw
           The input grid cell width and height.

       sar The input sample aspect ratio.

       x
       y   The x and y coordinates of some point of grid intersection (meant
           to configure offset).

       w
       h   The width and height of the drawn cell.

       t   The thickness of the drawn cell.

           These constants allow the x, y, w, h and t expressions to refer to
           each other, so you may for example specify "y=x/dar" or "h=w/dar".

       Examples

       o   Draw a grid with cell 100x100 pixels, thickness 2 pixels, with
           color red and an opacity of 50%:

                   drawgrid=width=100:height=100:thickness=2:color=red@0.5

       o   Draw a white 33 grid with an opacity of 50%:

                   drawgrid=w=iw/3:h=ih/3:t=2:c=white@0.5

       Commands

       This filter supports same commands as options.  The command accepts the
       same syntax of the corresponding option.

       If the specified expression is not valid, it is kept at its current
       value.

   drawtext
       Draw a text string or text from a specified file on top of a video,
       using the libfreetype library.

       To enable compilation of this filter, you need to configure FFmpeg with
       "--enable-libfreetype".  To enable default font fallback and the font
       option you need to configure FFmpeg with "--enable-libfontconfig".  To
       enable the text_shaping option, you need to configure FFmpeg with
       "--enable-libfribidi".

       Syntax

       It accepts the following parameters:

       box Used to draw a box around text using the background color.  The
           value must be either 1 (enable) or 0 (disable).  The default value
           of box is 0.

       boxborderw
           Set the width of the border to be drawn around the box using
           boxcolor.  The default value of boxborderw is 0.

       boxcolor
           The color to be used for drawing box around text. For the syntax of
           this option, check the "Color" section in the ffmpeg-utils manual.

           The default value of boxcolor is "white".

       line_spacing
           Set the line spacing in pixels of the border to be drawn around the
           box using box.  The default value of line_spacing is 0.

       borderw
           Set the width of the border to be drawn around the text using
           bordercolor.  The default value of borderw is 0.

       bordercolor
           Set the color to be used for drawing border around text. For the
           syntax of this option, check the "Color" section in the ffmpeg-
           utils manual.

           The default value of bordercolor is "black".

       expansion
           Select how the text is expanded. Can be either "none", "strftime"
           (deprecated) or "normal" (default). See the drawtext_expansion,
           Text expansion section below for details.

       basetime
           Set a start time for the count. Value is in microseconds. Only
           applied in the deprecated strftime expansion mode. To emulate in
           normal expansion mode use the "pts" function, supplying the start
           time (in seconds) as the second argument.

       fix_bounds
           If true, check and fix text coords to avoid clipping.

       fontcolor
           The color to be used for drawing fonts. For the syntax of this
           option, check the "Color" section in the ffmpeg-utils manual.

           The default value of fontcolor is "black".

       fontcolor_expr
           String which is expanded the same way as text to obtain dynamic
           fontcolor value. By default this option has empty value and is not
           processed. When this option is set, it overrides fontcolor option.

       font
           The font family to be used for drawing text. By default Sans.

       fontfile
           The font file to be used for drawing text. The path must be
           included.  This parameter is mandatory if the fontconfig support is
           disabled.

       alpha
           Draw the text applying alpha blending. The value can be a number
           between 0.0 and 1.0.  The expression accepts the same variables x,
           y as well.  The default value is 1.  Please see fontcolor_expr.

       fontsize
           The font size to be used for drawing text.  The default value of
           fontsize is 16.

       text_shaping
           If set to 1, attempt to shape the text (for example, reverse the
           order of right-to-left text and join Arabic characters) before
           drawing it.  Otherwise, just draw the text exactly as given.  By
           default 1 (if supported).

       ft_load_flags
           The flags to be used for loading the fonts.

           The flags map the corresponding flags supported by libfreetype, and
           are a combination of the following values:

           default
           no_scale
           no_hinting
           render
           no_bitmap
           vertical_layout
           force_autohint
           crop_bitmap
           pedantic
           ignore_global_advance_width
           no_recurse
           ignore_transform
           monochrome
           linear_design
           no_autohint

           Default value is "default".

           For more information consult the documentation for the FT_LOAD_*
           libfreetype flags.

       shadowcolor
           The color to be used for drawing a shadow behind the drawn text.
           For the syntax of this option, check the "Color" section in the
           ffmpeg-utils manual.

           The default value of shadowcolor is "black".

       shadowx
       shadowy
           The x and y offsets for the text shadow position with respect to
           the position of the text. They can be either positive or negative
           values. The default value for both is "0".

       start_number
           The starting frame number for the n/frame_num variable. The default
           value is "0".

       tabsize
           The size in number of spaces to use for rendering the tab.  Default
           value is 4.

       timecode
           Set the initial timecode representation in "hh:mm:ss[:;.]ff"
           format. It can be used with or without text parameter.
           timecode_rate option must be specified.

       timecode_rate, rate, r
           Set the timecode frame rate (timecode only). Value will be rounded
           to nearest integer. Minimum value is "1".  Drop-frame timecode is
           supported for frame rates 30 & 60.

       tc24hmax
           If set to 1, the output of the timecode option will wrap around at
           24 hours.  Default is 0 (disabled).

       text
           The text string to be drawn. The text must be a sequence of UTF-8
           encoded characters.  This parameter is mandatory if no file is
           specified with the parameter textfile.

       textfile
           A text file containing text to be drawn. The text must be a
           sequence of UTF-8 encoded characters.

           This parameter is mandatory if no text string is specified with the
           parameter text.

           If both text and textfile are specified, an error is thrown.

       reload
           If set to 1, the textfile will be reloaded before each frame.  Be
           sure to update it atomically, or it may be read partially, or even
           fail.

       x
       y   The expressions which specify the offsets where text will be drawn
           within the video frame. They are relative to the top/left border of
           the output image.

           The default value of x and y is "0".

           See below for the list of accepted constants and functions.

       The parameters for x and y are expressions containing the following
       constants and functions:

       dar input display aspect ratio, it is the same as (w / h) * sar

       hsub
       vsub
           horizontal and vertical chroma subsample values. For example for
           the pixel format "yuv422p" hsub is 2 and vsub is 1.

       line_h, lh
           the height of each text line

       main_h, h, H
           the input height

       main_w, w, W
           the input width

       max_glyph_a, ascent
           the maximum distance from the baseline to the highest/upper grid
           coordinate used to place a glyph outline point, for all the
           rendered glyphs.  It is a positive value, due to the grid's
           orientation with the Y axis upwards.

       max_glyph_d, descent
           the maximum distance from the baseline to the lowest grid
           coordinate used to place a glyph outline point, for all the
           rendered glyphs.  This is a negative value, due to the grid's
           orientation, with the Y axis upwards.

       max_glyph_h
           maximum glyph height, that is the maximum height for all the glyphs
           contained in the rendered text, it is equivalent to ascent -
           descent.

       max_glyph_w
           maximum glyph width, that is the maximum width for all the glyphs
           contained in the rendered text

       n   the number of input frame, starting from 0

       rand(min, max)
           return a random number included between min and max

       sar The input sample aspect ratio.

       t   timestamp expressed in seconds, NAN if the input timestamp is
           unknown

       text_h, th
           the height of the rendered text

       text_w, tw
           the width of the rendered text

       x
       y   the x and y offset coordinates where the text is drawn.

           These parameters allow the x and y expressions to refer to each
           other, so you can for example specify "y=x/dar".

       pict_type
           A one character description of the current frame's picture type.

       pkt_pos
           The current packet's position in the input file or stream (in
           bytes, from the start of the input). A value of -1 indicates this
           info is not available.

       pkt_duration
           The current packet's duration, in seconds.

       pkt_size
           The current packet's size (in bytes).

       Text expansion

       If expansion is set to "strftime", the filter recognizes strftime()
       sequences in the provided text and expands them accordingly. Check the
       documentation of strftime(). This feature is deprecated.

       If expansion is set to "none", the text is printed verbatim.

       If expansion is set to "normal" (which is the default), the following
       expansion mechanism is used.

       The backslash character \, followed by any character, always expands to
       the second character.

       Sequences of the form "%{...}" are expanded. The text between the
       braces is a function name, possibly followed by arguments separated by
       ':'.  If the arguments contain special characters or delimiters (':' or
       '}'), they should be escaped.

       Note that they probably must also be escaped as the value for the text
       option in the filter argument string and as the filter argument in the
       filtergraph description, and possibly also for the shell, that makes up
       to four levels of escaping; using a text file avoids these problems.

       The following functions are available:

       expr, e
           The expression evaluation result.

           It must take one argument specifying the expression to be
           evaluated, which accepts the same constants and functions as the x
           and y values. Note that not all constants should be used, for
           example the text size is not known when evaluating the expression,
           so the constants text_w and text_h will have an undefined value.

       expr_int_format, eif
           Evaluate the expression's value and output as formatted integer.

           The first argument is the expression to be evaluated, just as for
           the expr function.  The second argument specifies the output
           format. Allowed values are x, X, d and u. They are treated exactly
           as in the "printf" function.  The third parameter is optional and
           sets the number of positions taken by the output.  It can be used
           to add padding with zeros from the left.

       gmtime
           The time at which the filter is running, expressed in UTC.  It can
           accept an argument: a strftime() format string.

       localtime
           The time at which the filter is running, expressed in the local
           time zone.  It can accept an argument: a strftime() format string.

       metadata
           Frame metadata. Takes one or two arguments.

           The first argument is mandatory and specifies the metadata key.

           The second argument is optional and specifies a default value, used
           when the metadata key is not found or empty.

           Available metadata can be identified by inspecting entries starting
           with TAG included within each frame section printed by running
           "ffprobe -show_frames".

           String metadata generated in filters leading to the drawtext filter
           are also available.

       n, frame_num
           The frame number, starting from 0.

       pict_type
           A one character description of the current picture type.

       pts The timestamp of the current frame.  It can take up to three
           arguments.

           The first argument is the format of the timestamp; it defaults to
           "flt" for seconds as a decimal number with microsecond accuracy;
           "hms" stands for a formatted [-]HH:MM:SS.mmm timestamp with
           millisecond accuracy.  "gmtime" stands for the timestamp of the
           frame formatted as UTC time; "localtime" stands for the timestamp
           of the frame formatted as local time zone time.

           The second argument is an offset added to the timestamp.

           If the format is set to "hms", a third argument "24HH" may be
           supplied to present the hour part of the formatted timestamp in 24h
           format (00-23).

           If the format is set to "localtime" or "gmtime", a third argument
           may be supplied: a strftime() format string.  By default, YYYY-MM-
           DD HH:MM:SS format will be used.

       Commands

       This filter supports altering parameters via commands:

       reinit
           Alter existing filter parameters.

           Syntax for the argument is the same as for filter invocation, e.g.

                   fontsize=56:fontcolor=green:text='Hello World'

           Full filter invocation with sendcmd would look like this:

                   sendcmd=c='56.0 drawtext reinit fontsize=56\:fontcolor=green\:text=Hello\\ World'

       If the entire argument can't be parsed or applied as valid values then
       the filter will continue with its existing parameters.

       Examples

       o   Draw "Test Text" with font FreeSerif, using the default values for
           the optional parameters.

                   drawtext="fontfile=/usr/share/fonts/truetype/freefont/FreeSerif.ttf: text='Test Text'"

       o   Draw 'Test Text' with font FreeSerif of size 24 at position x=100
           and y=50 (counting from the top-left corner of the screen), text is
           yellow with a red box around it. Both the text and the box have an
           opacity of 20%.

                   drawtext="fontfile=/usr/share/fonts/truetype/freefont/FreeSerif.ttf: text='Test Text':\
                             x=100: y=50: fontsize=24: fontcolor=yellow@0.2: box=1: boxcolor=red@0.2"

           Note that the double quotes are not necessary if spaces are not
           used within the parameter list.

       o   Show the text at the center of the video frame:

                   drawtext="fontsize=30:fontfile=FreeSerif.ttf:text='hello world':x=(w-text_w)/2:y=(h-text_h)/2"

       o   Show the text at a random position, switching to a new position
           every 30 seconds:

                   drawtext="fontsize=30:fontfile=FreeSerif.ttf:text='hello world':x=if(eq(mod(t\,30)\,0)\,rand(0\,(w-text_w))\,x):y=if(eq(mod(t\,30)\,0)\,rand(0\,(h-text_h))\,y)"

       o   Show a text line sliding from right to left in the last row of the
           video frame. The file LONG_LINE is assumed to contain a single line
           with no newlines.

                   drawtext="fontsize=15:fontfile=FreeSerif.ttf:text=LONG_LINE:y=h-line_h:x=-50*t"

       o   Show the content of file CREDITS off the bottom of the frame and
           scroll up.

                   drawtext="fontsize=20:fontfile=FreeSerif.ttf:textfile=CREDITS:y=h-20*t"

       o   Draw a single green letter "g", at the center of the input video.
           The glyph baseline is placed at half screen height.

                   drawtext="fontsize=60:fontfile=FreeSerif.ttf:fontcolor=green:text=g:x=(w-max_glyph_w)/2:y=h/2-ascent"

       o   Show text for 1 second every 3 seconds:

                   drawtext="fontfile=FreeSerif.ttf:fontcolor=white:x=100:y=x/dar:enable=lt(mod(t\,3)\,1):text='blink'"

       o   Use fontconfig to set the font. Note that the colons need to be
           escaped.

                   drawtext='fontfile=Linux Libertine O-40\:style=Semibold:text=FFmpeg'

       o   Draw "Test Text" with font size dependent on height of the video.

                   drawtext="text='Test Text': fontsize=h/30: x=(w-text_w)/2: y=(h-text_h*2)"

       o   Print the date of a real-time encoding (see strftime(3)):

                   drawtext='fontfile=FreeSans.ttf:text=%{localtime\:%a %b %d %Y}'

       o   Show text fading in and out (appearing/disappearing):

                   #!/bin/sh
                   DS=1.0 # display start
                   DE=10.0 # display end
                   FID=1.5 # fade in duration
                   FOD=5 # fade out duration
                   ffplay -f lavfi "color,drawtext=text=TEST:fontsize=50:fontfile=FreeSerif.ttf:fontcolor_expr=ff0000%{eif\\\\: clip(255*(1*between(t\\, $DS + $FID\\, $DE - $FOD) + ((t - $DS)/$FID)*between(t\\, $DS\\, $DS + $FID) + (-(t - $DE)/$FOD)*between(t\\, $DE - $FOD\\, $DE) )\\, 0\\, 255) \\\\: x\\\\: 2 }"

       o   Horizontally align multiple separate texts. Note that max_glyph_a
           and the fontsize value are included in the y offset.

                   drawtext=fontfile=FreeSans.ttf:text=DOG:fontsize=24:x=10:y=20+24-max_glyph_a,
                   drawtext=fontfile=FreeSans.ttf:text=cow:fontsize=24:x=80:y=20+24-max_glyph_a

       o   Plot special lavf.image2dec.source_basename metadata onto each
           frame if such metadata exists. Otherwise, plot the string "NA".
           Note that image2 demuxer must have option -export_path_metadata 1
           for the special metadata fields to be available for filters.

                   drawtext="fontsize=20:fontcolor=white:fontfile=FreeSans.ttf:text='%{metadata\:lavf.image2dec.source_basename\:NA}':x=10:y=10"

       For more information about libfreetype, check:
       <http://www.freetype.org/>.

       For more information about fontconfig, check:
       <http://freedesktop.org/software/fontconfig/fontconfig-user.html>.

       For more information about libfribidi, check: <http://fribidi.org/>.

   edgedetect
       Detect and draw edges. The filter uses the Canny Edge Detection
       algorithm.

       The filter accepts the following options:

       low
       high
           Set low and high threshold values used by the Canny thresholding
           algorithm.

           The high threshold selects the "strong" edge pixels, which are then
           connected through 8-connectivity with the "weak" edge pixels
           selected by the low threshold.

           low and high threshold values must be chosen in the range [0,1],
           and low should be lesser or equal to high.

           Default value for low is "20/255", and default value for high is
           "50/255".

       mode
           Define the drawing mode.

           wires
               Draw white/gray wires on black background.

           colormix
               Mix the colors to create a paint/cartoon effect.

           canny
               Apply Canny edge detector on all selected planes.

           Default value is wires.

       planes
           Select planes for filtering. By default all available planes are
           filtered.

       Examples

       o   Standard edge detection with custom values for the hysteresis
           thresholding:

                   edgedetect=low=0.1:high=0.4

       o   Painting effect without thresholding:

                   edgedetect=mode=colormix:high=0

   elbg
       Apply a posterize effect using the ELBG (Enhanced LBG) algorithm.

       For each input image, the filter will compute the optimal mapping from
       the input to the output given the codebook length, that is the number
       of distinct output colors.

       This filter accepts the following options.

       codebook_length, l
           Set codebook length. The value must be a positive integer, and
           represents the number of distinct output colors. Default value is
           256.

       nb_steps, n
           Set the maximum number of iterations to apply for computing the
           optimal mapping. The higher the value the better the result and the
           higher the computation time. Default value is 1.

       seed, s
           Set a random seed, must be an integer included between 0 and
           UINT32_MAX. If not specified, or if explicitly set to -1, the
           filter will try to use a good random seed on a best effort basis.

       pal8
           Set pal8 output pixel format. This option does not work with
           codebook length greater than 256.

   entropy
       Measure graylevel entropy in histogram of color channels of video
       frames.

       It accepts the following parameters:

       mode
           Can be either normal or diff. Default is normal.

           diff mode measures entropy of histogram delta values, absolute
           differences between neighbour histogram values.

   epx
       Apply the EPX magnification filter which is designed for pixel art.

       It accepts the following option:

       n   Set the scaling dimension: 2 for "2xEPX", 3 for "3EPX".  Default
           is 3.

   eq
       Set brightness, contrast, saturation and approximate gamma adjustment.

       The filter accepts the following options:

       contrast
           Set the contrast expression. The value must be a float value in
           range "-1000.0" to 1000.0. The default value is "1".

       brightness
           Set the brightness expression. The value must be a float value in
           range "-1.0" to 1.0. The default value is "0".

       saturation
           Set the saturation expression. The value must be a float in range
           0.0 to 3.0. The default value is "1".

       gamma
           Set the gamma expression. The value must be a float in range 0.1 to
           10.0.  The default value is "1".

       gamma_r
           Set the gamma expression for red. The value must be a float in
           range 0.1 to 10.0. The default value is "1".

       gamma_g
           Set the gamma expression for green. The value must be a float in
           range 0.1 to 10.0. The default value is "1".

       gamma_b
           Set the gamma expression for blue. The value must be a float in
           range 0.1 to 10.0. The default value is "1".

       gamma_weight
           Set the gamma weight expression. It can be used to reduce the
           effect of a high gamma value on bright image areas, e.g. keep them
           from getting overamplified and just plain white. The value must be
           a float in range 0.0 to 1.0. A value of 0.0 turns the gamma
           correction all the way down while 1.0 leaves it at its full
           strength. Default is "1".

       eval
           Set when the expressions for brightness, contrast, saturation and
           gamma expressions are evaluated.

           It accepts the following values:

           init
               only evaluate expressions once during the filter initialization
               or when a command is processed

           frame
               evaluate expressions for each incoming frame

           Default value is init.

       The expressions accept the following parameters:

       n   frame count of the input frame starting from 0

       pos byte position of the corresponding packet in the input file, NAN if
           unspecified

       r   frame rate of the input video, NAN if the input frame rate is
           unknown

       t   timestamp expressed in seconds, NAN if the input timestamp is
           unknown

       Commands

       The filter supports the following commands:

       contrast
           Set the contrast expression.

       brightness
           Set the brightness expression.

       saturation
           Set the saturation expression.

       gamma
           Set the gamma expression.

       gamma_r
           Set the gamma_r expression.

       gamma_g
           Set gamma_g expression.

       gamma_b
           Set gamma_b expression.

       gamma_weight
           Set gamma_weight expression.

           The command accepts the same syntax of the corresponding option.

           If the specified expression is not valid, it is kept at its current
           value.

   erosion
       Apply erosion effect to the video.

       This filter replaces the pixel by the local(33) minimum.

       It accepts the following options:

       threshold0
       threshold1
       threshold2
       threshold3
           Limit the maximum change for each plane, default is 65535.  If 0,
           plane will remain unchanged.

       coordinates
           Flag which specifies the pixel to refer to. Default is 255 i.e. all
           eight pixels are used.

           Flags to local 33 coordinates maps like this:

               1 2 3
               4   5
               6 7 8

       Commands

       This filter supports the all above options as commands.

   estdif
       Deinterlace the input video ("estdif" stands for "Edge Slope Tracing
       Deinterlacing Filter").

       Spatial only filter that uses edge slope tracing algorithm to
       interpolate missing lines.  It accepts the following parameters:

       mode
           The interlacing mode to adopt. It accepts one of the following
           values:

           frame
               Output one frame for each frame.

           field
               Output one frame for each field.

           The default value is "field".

       parity
           The picture field parity assumed for the input interlaced video. It
           accepts one of the following values:

           tff Assume the top field is first.

           bff Assume the bottom field is first.

           auto
               Enable automatic detection of field parity.

           The default value is "auto".  If the interlacing is unknown or the
           decoder does not export this information, top field first will be
           assumed.

       deint
           Specify which frames to deinterlace. Accepts one of the following
           values:

           all Deinterlace all frames.

           interlaced
               Only deinterlace frames marked as interlaced.

           The default value is "all".

       rslope
           Specify the search radius for edge slope tracing. Default value is
           1.  Allowed range is from 1 to 15.

       redge
           Specify the search radius for best edge matching. Default value is
           2.  Allowed range is from 0 to 15.

       interp
           Specify the interpolation used. Default is 4-point interpolation.
           It accepts one of the following values:

           2p  Two-point interpolation.

           4p  Four-point interpolation.

           6p  Six-point interpolation.

       Commands

       This filter supports same commands as options.

   exposure
       Adjust exposure of the video stream.

       The filter accepts the following options:

       exposure
           Set the exposure correction in EV. Allowed range is from -3.0 to
           3.0 EV Default value is 0 EV.

       black
           Set the black level correction. Allowed range is from -1.0 to 1.0.
           Default value is 0.

       Commands

       This filter supports same commands as options.

   extractplanes
       Extract color channel components from input video stream into separate
       grayscale video streams.

       The filter accepts the following option:

       planes
           Set plane(s) to extract.

           Available values for planes are:

           y
           u
           v
           a
           r
           g
           b

           Choosing planes not available in the input will result in an error.
           That means you cannot select "r", "g", "b" planes with "y", "u",
           "v" planes at same time.

       Examples

       o   Extract luma, u and v color channel component from input video
           frame into 3 grayscale outputs:

                   ffmpeg -i video.avi -filter_complex 'extractplanes=y+u+v[y][u][v]' -map '[y]' y.avi -map '[u]' u.avi -map '[v]' v.avi

   fade
       Apply a fade-in/out effect to the input video.

       It accepts the following parameters:

       type, t
           The effect type can be either "in" for a fade-in, or "out" for a
           fade-out effect.  Default is "in".

       start_frame, s
           Specify the number of the frame to start applying the fade effect
           at. Default is 0.

       nb_frames, n
           The number of frames that the fade effect lasts. At the end of the
           fade-in effect, the output video will have the same intensity as
           the input video.  At the end of the fade-out transition, the output
           video will be filled with the selected color.  Default is 25.

       alpha
           If set to 1, fade only alpha channel, if one exists on the input.
           Default value is 0.

       start_time, st
           Specify the timestamp (in seconds) of the frame to start to apply
           the fade effect. If both start_frame and start_time are specified,
           the fade will start at whichever comes last.  Default is 0.

       duration, d
           The number of seconds for which the fade effect has to last. At the
           end of the fade-in effect the output video will have the same
           intensity as the input video, at the end of the fade-out transition
           the output video will be filled with the selected color.  If both
           duration and nb_frames are specified, duration is used. Default is
           0 (nb_frames is used by default).

       color, c
           Specify the color of the fade. Default is "black".

       Examples

       o   Fade in the first 30 frames of video:

                   fade=in:0:30

           The command above is equivalent to:

                   fade=t=in:s=0:n=30

       o   Fade out the last 45 frames of a 200-frame video:

                   fade=out:155:45
                   fade=type=out:start_frame=155:nb_frames=45

       o   Fade in the first 25 frames and fade out the last 25 frames of a
           1000-frame video:

                   fade=in:0:25, fade=out:975:25

       o   Make the first 5 frames yellow, then fade in from frame 5-24:

                   fade=in:5:20:color=yellow

       o   Fade in alpha over first 25 frames of video:

                   fade=in:0:25:alpha=1

       o   Make the first 5.5 seconds black, then fade in for 0.5 seconds:

                   fade=t=in:st=5.5:d=0.5

   fftdnoiz
       Denoise frames using 3D FFT (frequency domain filtering).

       The filter accepts the following options:

       sigma
           Set the noise sigma constant. This sets denoising strength.
           Default value is 1. Allowed range is from 0 to 30.  Using very high
           sigma with low overlap may give blocking artifacts.

       amount
           Set amount of denoising. By default all detected noise is reduced.
           Default value is 1. Allowed range is from 0 to 1.

       block
           Set size of block, Default is 4, can be 3, 4, 5 or 6.  Actual size
           of block in pixels is 2 to power of block, so by default block size
           in pixels is 2^4 which is 16.

       overlap
           Set block overlap. Default is 0.5. Allowed range is from 0.2 to
           0.8.

       prev
           Set number of previous frames to use for denoising. By default is
           set to 0.

       next
           Set number of next frames to to use for denoising. By default is
           set to 0.

       planes
           Set planes which will be filtered, by default are all available
           filtered except alpha.

   fftfilt
       Apply arbitrary expressions to samples in frequency domain

       dc_Y
           Adjust the dc value (gain) of the luma plane of the image. The
           filter accepts an integer value in range 0 to 1000. The default
           value is set to 0.

       dc_U
           Adjust the dc value (gain) of the 1st chroma plane of the image.
           The filter accepts an integer value in range 0 to 1000. The default
           value is set to 0.

       dc_V
           Adjust the dc value (gain) of the 2nd chroma plane of the image.
           The filter accepts an integer value in range 0 to 1000. The default
           value is set to 0.

       weight_Y
           Set the frequency domain weight expression for the luma plane.

       weight_U
           Set the frequency domain weight expression for the 1st chroma
           plane.

       weight_V
           Set the frequency domain weight expression for the 2nd chroma
           plane.

       eval
           Set when the expressions are evaluated.

           It accepts the following values:

           init
               Only evaluate expressions once during the filter
               initialization.

           frame
               Evaluate expressions for each incoming frame.

           Default value is init.

           The filter accepts the following variables:

       X
       Y   The coordinates of the current sample.

       W
       H   The width and height of the image.

       N   The number of input frame, starting from 0.

       Examples

       o   High-pass:

                   fftfilt=dc_Y=128:weight_Y='squish(1-(Y+X)/100)'

       o   Low-pass:

                   fftfilt=dc_Y=0:weight_Y='squish((Y+X)/100-1)'

       o   Sharpen:

                   fftfilt=dc_Y=0:weight_Y='1+squish(1-(Y+X)/100)'

       o   Blur:

                   fftfilt=dc_Y=0:weight_Y='exp(-4 * ((Y+X)/(W+H)))'

   field
       Extract a single field from an interlaced image using stride arithmetic
       to avoid wasting CPU time. The output frames are marked as non-
       interlaced.

       The filter accepts the following options:

       type
           Specify whether to extract the top (if the value is 0 or "top") or
           the bottom field (if the value is 1 or "bottom").

   fieldhint
       Create new frames by copying the top and bottom fields from surrounding
       frames supplied as numbers by the hint file.

       hint
           Set file containing hints: absolute/relative frame numbers.

           There must be one line for each frame in a clip. Each line must
           contain two numbers separated by the comma, optionally followed by
           "-" or "+".  Numbers supplied on each line of file can not be out
           of [N-1,N+1] where N is current frame number for "absolute" mode or
           out of [-1, 1] range for "relative" mode. First number tells from
           which frame to pick up top field and second number tells from which
           frame to pick up bottom field.

           If optionally followed by "+" output frame will be marked as
           interlaced, else if followed by "-" output frame will be marked as
           progressive, else it will be marked same as input frame.  If
           optionally followed by "t" output frame will use only top field, or
           in case of "b" it will use only bottom field.  If line starts with
           "#" or ";" that line is skipped.

       mode
           Can be item "absolute" or "relative". Default is "absolute".

       Example of first several lines of "hint" file for "relative" mode:

               0,0 - # first frame
               1,0 - # second frame, use third's frame top field and second's frame bottom field
               1,0 - # third frame, use fourth's frame top field and third's frame bottom field
               1,0 -
               0,0 -
               0,0 -
               1,0 -
               1,0 -
               1,0 -
               0,0 -
               0,0 -
               1,0 -
               1,0 -
               1,0 -
               0,0 -

   fieldmatch
       Field matching filter for inverse telecine. It is meant to reconstruct
       the progressive frames from a telecined stream. The filter does not
       drop duplicated frames, so to achieve a complete inverse telecine
       "fieldmatch" needs to be followed by a decimation filter such as
       decimate in the filtergraph.

       The separation of the field matching and the decimation is notably
       motivated by the possibility of inserting a de-interlacing filter
       fallback between the two.  If the source has mixed telecined and real
       interlaced content, "fieldmatch" will not be able to match fields for
       the interlaced parts.  But these remaining combed frames will be marked
       as interlaced, and thus can be de-interlaced by a later filter such as
       yadif before decimation.

       In addition to the various configuration options, "fieldmatch" can take
       an optional second stream, activated through the ppsrc option. If
       enabled, the frames reconstruction will be based on the fields and
       frames from this second stream. This allows the first input to be pre-
       processed in order to help the various algorithms of the filter, while
       keeping the output lossless (assuming the fields are matched properly).
       Typically, a field-aware denoiser, or brightness/contrast adjustments
       can help.

       Note that this filter uses the same algorithms as TIVTC/TFM (AviSynth
       project) and VIVTC/VFM (VapourSynth project). The later is a light
       clone of TFM from which "fieldmatch" is based on. While the semantic
       and usage are very close, some behaviour and options names can differ.

       The decimate filter currently only works for constant frame rate input.
       If your input has mixed telecined (30fps) and progressive content with
       a lower framerate like 24fps use the following filterchain to produce
       the necessary cfr stream:
       "dejudder,fps=30000/1001,fieldmatch,decimate".

       The filter accepts the following options:

       order
           Specify the assumed field order of the input stream. Available
           values are:

           auto
               Auto detect parity (use FFmpeg's internal parity value).

           bff Assume bottom field first.

           tff Assume top field first.

           Note that it is sometimes recommended not to trust the parity
           announced by the stream.

           Default value is auto.

       mode
           Set the matching mode or strategy to use. pc mode is the safest in
           the sense that it won't risk creating jerkiness due to duplicate
           frames when possible, but if there are bad edits or blended fields
           it will end up outputting combed frames when a good match might
           actually exist. On the other hand, pcn_ub mode is the most risky in
           terms of creating jerkiness, but will almost always find a good
           frame if there is one. The other values are all somewhere in
           between pc and pcn_ub in terms of risking jerkiness and creating
           duplicate frames versus finding good matches in sections with bad
           edits, orphaned fields, blended fields, etc.

           More details about p/c/n/u/b are available in p/c/n/u/b meaning
           section.

           Available values are:

           pc  2-way matching (p/c)

           pc_n
               2-way matching, and trying 3rd match if still combed (p/c + n)

           pc_u
               2-way matching, and trying 3rd match (same order) if still
               combed (p/c + u)

           pc_n_ub
               2-way matching, trying 3rd match if still combed, and trying
               4th/5th matches if still combed (p/c + n + u/b)

           pcn 3-way matching (p/c/n)

           pcn_ub
               3-way matching, and trying 4th/5th matches if all 3 of the
               original matches are detected as combed (p/c/n + u/b)

           The parenthesis at the end indicate the matches that would be used
           for that mode assuming order=tff (and field on auto or top).

           In terms of speed pc mode is by far the fastest and pcn_ub is the
           slowest.

           Default value is pc_n.

       ppsrc
           Mark the main input stream as a pre-processed input, and enable the
           secondary input stream as the clean source to pick the fields from.
           See the filter introduction for more details. It is similar to the
           clip2 feature from VFM/TFM.

           Default value is 0 (disabled).

       field
           Set the field to match from. It is recommended to set this to the
           same value as order unless you experience matching failures with
           that setting. In certain circumstances changing the field that is
           used to match from can have a large impact on matching performance.
           Available values are:

           auto
               Automatic (same value as order).

           bottom
               Match from the bottom field.

           top Match from the top field.

           Default value is auto.

       mchroma
           Set whether or not chroma is included during the match comparisons.
           In most cases it is recommended to leave this enabled. You should
           set this to 0 only if your clip has bad chroma problems such as
           heavy rainbowing or other artifacts. Setting this to 0 could also
           be used to speed things up at the cost of some accuracy.

           Default value is 1.

       y0
       y1  These define an exclusion band which excludes the lines between y0
           and y1 from being included in the field matching decision. An
           exclusion band can be used to ignore subtitles, a logo, or other
           things that may interfere with the matching. y0 sets the starting
           scan line and y1 sets the ending line; all lines in between y0 and
           y1 (including y0 and y1) will be ignored. Setting y0 and y1 to the
           same value will disable the feature.  y0 and y1 defaults to 0.

       scthresh
           Set the scene change detection threshold as a percentage of maximum
           change on the luma plane. Good values are in the "[8.0, 14.0]"
           range. Scene change detection is only relevant in case
           combmatch=sc.  The range for scthresh is "[0.0, 100.0]".

           Default value is 12.0.

       combmatch
           When combatch is not none, "fieldmatch" will take into account the
           combed scores of matches when deciding what match to use as the
           final match. Available values are:

           none
               No final matching based on combed scores.

           sc  Combed scores are only used when a scene change is detected.

           full
               Use combed scores all the time.

           Default is sc.

       combdbg
           Force "fieldmatch" to calculate the combed metrics for certain
           matches and print them. This setting is known as micout in TFM/VFM
           vocabulary.  Available values are:

           none
               No forced calculation.

           pcn Force p/c/n calculations.

           pcnub
               Force p/c/n/u/b calculations.

           Default value is none.

       cthresh
           This is the area combing threshold used for combed frame detection.
           This essentially controls how "strong" or "visible" combing must be
           to be detected.  Larger values mean combing must be more visible
           and smaller values mean combing can be less visible or strong and
           still be detected. Valid settings are from "-1" (every pixel will
           be detected as combed) to 255 (no pixel will be detected as
           combed). This is basically a pixel difference value. A good range
           is "[8, 12]".

           Default value is 9.

       chroma
           Sets whether or not chroma is considered in the combed frame
           decision.  Only disable this if your source has chroma problems
           (rainbowing, etc.) that are causing problems for the combed frame
           detection with chroma enabled. Actually, using chroma=0 is usually
           more reliable, except for the case where there is chroma only
           combing in the source.

           Default value is 0.

       blockx
       blocky
           Respectively set the x-axis and y-axis size of the window used
           during combed frame detection. This has to do with the size of the
           area in which combpel pixels are required to be detected as combed
           for a frame to be declared combed. See the combpel parameter
           description for more info.  Possible values are any number that is
           a power of 2 starting at 4 and going up to 512.

           Default value is 16.

       combpel
           The number of combed pixels inside any of the blocky by blockx size
           blocks on the frame for the frame to be detected as combed. While
           cthresh controls how "visible" the combing must be, this setting
           controls "how much" combing there must be in any localized area (a
           window defined by the blockx and blocky settings) on the frame.
           Minimum value is 0 and maximum is "blocky x blockx" (at which point
           no frames will ever be detected as combed). This setting is known
           as MI in TFM/VFM vocabulary.

           Default value is 80.

       p/c/n/u/b meaning

       p/c/n

       We assume the following telecined stream:

               Top fields:     1 2 2 3 4
               Bottom fields:  1 2 3 4 4

       The numbers correspond to the progressive frame the fields relate to.
       Here, the first two frames are progressive, the 3rd and 4th are combed,
       and so on.

       When "fieldmatch" is configured to run a matching from bottom
       (field=bottom) this is how this input stream get transformed:

               Input stream:
                               T     1 2 2 3 4
                               B     1 2 3 4 4   <-- matching reference

               Matches:              c c n n c

               Output stream:
                               T     1 2 3 4 4
                               B     1 2 3 4 4

       As a result of the field matching, we can see that some frames get
       duplicated.  To perform a complete inverse telecine, you need to rely
       on a decimation filter after this operation. See for instance the
       decimate filter.

       The same operation now matching from top fields (field=top) looks like
       this:

               Input stream:
                               T     1 2 2 3 4   <-- matching reference
                               B     1 2 3 4 4

               Matches:              c c p p c

               Output stream:
                               T     1 2 2 3 4
                               B     1 2 2 3 4

       In these examples, we can see what p, c and n mean; basically, they
       refer to the frame and field of the opposite parity:

       *<p matches the field of the opposite parity in the previous frame>
       *<c matches the field of the opposite parity in the current frame>
       *<n matches the field of the opposite parity in the next frame>

       u/b

       The u and b matching are a bit special in the sense that they match
       from the opposite parity flag. In the following examples, we assume
       that we are currently matching the 2nd frame (Top:2, bottom:2).
       According to the match, a 'x' is placed above and below each matched
       fields.

       With bottom matching (field=bottom):

               Match:           c         p           n          b          u

                                x       x               x        x          x
                 Top          1 2 2     1 2 2       1 2 2      1 2 2      1 2 2
                 Bottom       1 2 3     1 2 3       1 2 3      1 2 3      1 2 3
                                x         x           x        x              x

               Output frames:
                                2          1          2          2          2
                                2          2          2          1          3

       With top matching (field=top):

               Match:           c         p           n          b          u

                                x         x           x        x              x
                 Top          1 2 2     1 2 2       1 2 2      1 2 2      1 2 2
                 Bottom       1 2 3     1 2 3       1 2 3      1 2 3      1 2 3
                                x       x               x        x          x

               Output frames:
                                2          2          2          1          2
                                2          1          3          2          2

       Examples

       Simple IVTC of a top field first telecined stream:

               fieldmatch=order=tff:combmatch=none, decimate

       Advanced IVTC, with fallback on yadif for still combed frames:

               fieldmatch=order=tff:combmatch=full, yadif=deint=interlaced, decimate

   fieldorder
       Transform the field order of the input video.

       It accepts the following parameters:

       order
           The output field order. Valid values are tff for top field first or
           bff for bottom field first.

       The default value is tff.

       The transformation is done by shifting the picture content up or down
       by one line, and filling the remaining line with appropriate picture
       content.  This method is consistent with most broadcast field order
       converters.

       If the input video is not flagged as being interlaced, or it is already
       flagged as being of the required output field order, then this filter
       does not alter the incoming video.

       It is very useful when converting to or from PAL DV material, which is
       bottom field first.

       For example:

               ffmpeg -i in.vob -vf "fieldorder=bff" out.dv

   fifo, afifo
       Buffer input images and send them when they are requested.

       It is mainly useful when auto-inserted by the libavfilter framework.

       It does not take parameters.

   fillborders
       Fill borders of the input video, without changing video stream
       dimensions.  Sometimes video can have garbage at the four edges and you
       may not want to crop video input to keep size multiple of some number.

       This filter accepts the following options:

       left
           Number of pixels to fill from left border.

       right
           Number of pixels to fill from right border.

       top Number of pixels to fill from top border.

       bottom
           Number of pixels to fill from bottom border.

       mode
           Set fill mode.

           It accepts the following values:

           smear
               fill pixels using outermost pixels

           mirror
               fill pixels using mirroring (half sample symmetric)

           fixed
               fill pixels with constant value

           reflect
               fill pixels using reflecting (whole sample symmetric)

           wrap
               fill pixels using wrapping

           fade
               fade pixels to constant value

           Default is smear.

       color
           Set color for pixels in fixed or fade mode. Default is black.

       Commands

       This filter supports same commands as options.  The command accepts the
       same syntax of the corresponding option.

       If the specified expression is not valid, it is kept at its current
       value.

   find_rect
       Find a rectangular object

       It accepts the following options:

       object
           Filepath of the object image, needs to be in gray8.

       threshold
           Detection threshold, default is 0.5.

       mipmaps
           Number of mipmaps, default is 3.

       xmin, ymin, xmax, ymax
           Specifies the rectangle in which to search.

       Examples

       o   Cover a rectangular object by the supplied image of a given video
           using ffmpeg:

                   ffmpeg -i file.ts -vf find_rect=newref.pgm,cover_rect=cover.jpg:mode=cover new.mkv

   floodfill
       Flood area with values of same pixel components with another values.

       It accepts the following options:

       x   Set pixel x coordinate.

       y   Set pixel y coordinate.

       s0  Set source #0 component value.

       s1  Set source #1 component value.

       s2  Set source #2 component value.

       s3  Set source #3 component value.

       d0  Set destination #0 component value.

       d1  Set destination #1 component value.

       d2  Set destination #2 component value.

       d3  Set destination #3 component value.

   format
       Convert the input video to one of the specified pixel formats.
       Libavfilter will try to pick one that is suitable as input to the next
       filter.

       It accepts the following parameters:

       pix_fmts
           A '|'-separated list of pixel format names, such as
           "pix_fmts=yuv420p|monow|rgb24".

       Examples

       o   Convert the input video to the yuv420p format

                   format=pix_fmts=yuv420p

           Convert the input video to any of the formats in the list

                   format=pix_fmts=yuv420p|yuv444p|yuv410p

   fps
       Convert the video to specified constant frame rate by duplicating or
       dropping frames as necessary.

       It accepts the following parameters:

       fps The desired output frame rate. The default is 25.

       start_time
           Assume the first PTS should be the given value, in seconds. This
           allows for padding/trimming at the start of stream. By default, no
           assumption is made about the first frame's expected PTS, so no
           padding or trimming is done.  For example, this could be set to 0
           to pad the beginning with duplicates of the first frame if a video
           stream starts after the audio stream or to trim any frames with a
           negative PTS.

       round
           Timestamp (PTS) rounding method.

           Possible values are:

           zero
               round towards 0

           inf round away from 0

           down
               round towards -infinity

           up  round towards +infinity

           near
               round to nearest

           The default is "near".

       eof_action
           Action performed when reading the last frame.

           Possible values are:

           round
               Use same timestamp rounding method as used for other frames.

           pass
               Pass through last frame if input duration has not been reached
               yet.

           The default is "round".

       Alternatively, the options can be specified as a flat string:
       fps[:start_time[:round]].

       See also the setpts filter.

       Examples

       o   A typical usage in order to set the fps to 25:

                   fps=fps=25

       o   Sets the fps to 24, using abbreviation and rounding method to round
           to nearest:

                   fps=fps=film:round=near

   framepack
       Pack two different video streams into a stereoscopic video, setting
       proper metadata on supported codecs. The two views should have the same
       size and framerate and processing will stop when the shorter video
       ends. Please note that you may conveniently adjust view properties with
       the scale and fps filters.

       It accepts the following parameters:

       format
           The desired packing format. Supported values are:

           sbs The views are next to each other (default).

           tab The views are on top of each other.

           lines
               The views are packed by line.

           columns
               The views are packed by column.

           frameseq
               The views are temporally interleaved.

       Some examples:

               # Convert left and right views into a frame-sequential video
               ffmpeg -i LEFT -i RIGHT -filter_complex framepack=frameseq OUTPUT

               # Convert views into a side-by-side video with the same output resolution as the input
               ffmpeg -i LEFT -i RIGHT -filter_complex [0:v]scale=w=iw/2[left],[1:v]scale=w=iw/2[right],[left][right]framepack=sbs OUTPUT

   framerate
       Change the frame rate by interpolating new video output frames from the
       source frames.

       This filter is not designed to function correctly with interlaced
       media. If you wish to change the frame rate of interlaced media then
       you are required to deinterlace before this filter and re-interlace
       after this filter.

       A description of the accepted options follows.

       fps Specify the output frames per second. This option can also be
           specified as a value alone. The default is 50.

       interp_start
           Specify the start of a range where the output frame will be created
           as a linear interpolation of two frames. The range is [0-255], the
           default is 15.

       interp_end
           Specify the end of a range where the output frame will be created
           as a linear interpolation of two frames. The range is [0-255], the
           default is 240.

       scene
           Specify the level at which a scene change is detected as a value
           between 0 and 100 to indicate a new scene; a low value reflects a
           low probability for the current frame to introduce a new scene,
           while a higher value means the current frame is more likely to be
           one.  The default is 8.2.

       flags
           Specify flags influencing the filter process.

           Available value for flags is:

           scene_change_detect, scd
               Enable scene change detection using the value of the option
               scene.  This flag is enabled by default.

   framestep
       Select one frame every N-th frame.

       This filter accepts the following option:

       step
           Select frame after every "step" frames.  Allowed values are
           positive integers higher than 0. Default value is 1.

   freezedetect
       Detect frozen video.

       This filter logs a message and sets frame metadata when it detects that
       the input video has no significant change in content during a specified
       duration.  Video freeze detection calculates the mean average absolute
       difference of all the components of video frames and compares it to a
       noise floor.

       The printed times and duration are expressed in seconds. The
       "lavfi.freezedetect.freeze_start" metadata key is set on the first
       frame whose timestamp equals or exceeds the detection duration and it
       contains the timestamp of the first frame of the freeze. The
       "lavfi.freezedetect.freeze_duration" and
       "lavfi.freezedetect.freeze_end" metadata keys are set on the first
       frame after the freeze.

       The filter accepts the following options:

       noise, n
           Set noise tolerance. Can be specified in dB (in case "dB" is
           appended to the specified value) or as a difference ratio between 0
           and 1. Default is -60dB, or 0.001.

       duration, d
           Set freeze duration until notification (default is 2 seconds).

   freezeframes
       Freeze video frames.

       This filter freezes video frames using frame from 2nd input.

       The filter accepts the following options:

       first
           Set number of first frame from which to start freeze.

       last
           Set number of last frame from which to end freeze.

       replace
           Set number of frame from 2nd input which will be used instead of
           replaced frames.

   frei0r
       Apply a frei0r effect to the input video.

       To enable the compilation of this filter, you need to install the
       frei0r header and configure FFmpeg with "--enable-frei0r".

       It accepts the following parameters:

       filter_name
           The name of the frei0r effect to load. If the environment variable
           FREI0R_PATH is defined, the frei0r effect is searched for in each
           of the directories specified by the colon-separated list in
           FREI0R_PATH.  Otherwise, the standard frei0r paths are searched, in
           this order: HOME/.frei0r-1/lib/, /usr/local/lib/frei0r-1/,
           /usr/lib/frei0r-1/.

       filter_params
           A '|'-separated list of parameters to pass to the frei0r effect.

       A frei0r effect parameter can be a boolean (its value is either "y" or
       "n"), a double, a color (specified as R/G/B, where R, G, and B are
       floating point numbers between 0.0 and 1.0, inclusive) or a color
       description as specified in the "Color" section in the ffmpeg-utils
       manual, a position (specified as X/Y, where X and Y are floating point
       numbers) and/or a string.

       The number and types of parameters depend on the loaded effect. If an
       effect parameter is not specified, the default value is set.

       Examples

       o   Apply the distort0r effect, setting the first two double
           parameters:

                   frei0r=filter_name=distort0r:filter_params=0.5|0.01

       o   Apply the colordistance effect, taking a color as the first
           parameter:

                   frei0r=colordistance:0.2/0.3/0.4
                   frei0r=colordistance:violet
                   frei0r=colordistance:0x112233

       o   Apply the perspective effect, specifying the top left and top right
           image positions:

                   frei0r=perspective:0.2/0.2|0.8/0.2

       For more information, see <http://frei0r.dyne.org>

       Commands

       This filter supports the filter_params option as commands.

   fspp
       Apply fast and simple postprocessing. It is a faster version of spp.

       It splits (I)DCT into horizontal/vertical passes. Unlike the simple
       post- processing filter, one of them is performed once per block, not
       per pixel.  This allows for much higher speed.

       The filter accepts the following options:

       quality
           Set quality. This option defines the number of levels for
           averaging. It accepts an integer in the range 4-5. Default value is
           4.

       qp  Force a constant quantization parameter. It accepts an integer in
           range 0-63.  If not set, the filter will use the QP from the video
           stream (if available).

       strength
           Set filter strength. It accepts an integer in range -15 to 32.
           Lower values mean more details but also more artifacts, while
           higher values make the image smoother but also blurrier. Default
           value is 0 X PSNR optimal.

       use_bframe_qp
           Enable the use of the QP from the B-Frames if set to 1. Using this
           option may cause flicker since the B-Frames have often larger QP.
           Default is 0 (not enabled).

   gblur
       Apply Gaussian blur filter.

       The filter accepts the following options:

       sigma
           Set horizontal sigma, standard deviation of Gaussian blur. Default
           is 0.5.

       steps
           Set number of steps for Gaussian approximation. Default is 1.

       planes
           Set which planes to filter. By default all planes are filtered.

       sigmaV
           Set vertical sigma, if negative it will be same as "sigma".
           Default is "-1".

       Commands

       This filter supports same commands as options.  The command accepts the
       same syntax of the corresponding option.

       If the specified expression is not valid, it is kept at its current
       value.

   geq
       Apply generic equation to each pixel.

       The filter accepts the following options:

       lum_expr, lum
           Set the luminance expression.

       cb_expr, cb
           Set the chrominance blue expression.

       cr_expr, cr
           Set the chrominance red expression.

       alpha_expr, a
           Set the alpha expression.

       red_expr, r
           Set the red expression.

       green_expr, g
           Set the green expression.

       blue_expr, b
           Set the blue expression.

       The colorspace is selected according to the specified options. If one
       of the lum_expr, cb_expr, or cr_expr options is specified, the filter
       will automatically select a YCbCr colorspace. If one of the red_expr,
       green_expr, or blue_expr options is specified, it will select an RGB
       colorspace.

       If one of the chrominance expression is not defined, it falls back on
       the other one. If no alpha expression is specified it will evaluate to
       opaque value.  If none of chrominance expressions are specified, they
       will evaluate to the luminance expression.

       The expressions can use the following variables and functions:

       N   The sequential number of the filtered frame, starting from 0.

       X
       Y   The coordinates of the current sample.

       W
       H   The width and height of the image.

       SW
       SH  Width and height scale depending on the currently filtered plane.
           It is the ratio between the corresponding luma plane number of
           pixels and the current plane ones. E.g. for YUV4:2:0 the values are
           "1,1" for the luma plane, and "0.5,0.5" for chroma planes.

       T   Time of the current frame, expressed in seconds.

       p(x, y)
           Return the value of the pixel at location (x,y) of the current
           plane.

       lum(x, y)
           Return the value of the pixel at location (x,y) of the luminance
           plane.

       cb(x, y)
           Return the value of the pixel at location (x,y) of the blue-
           difference chroma plane. Return 0 if there is no such plane.

       cr(x, y)
           Return the value of the pixel at location (x,y) of the red-
           difference chroma plane. Return 0 if there is no such plane.

       r(x, y)
       g(x, y)
       b(x, y)
           Return the value of the pixel at location (x,y) of the
           red/green/blue component. Return 0 if there is no such component.

       alpha(x, y)
           Return the value of the pixel at location (x,y) of the alpha plane.
           Return 0 if there is no such plane.

       psum(x,y), lumsum(x, y), cbsum(x,y), crsum(x,y), rsum(x,y), gsum(x,y),
       bsum(x,y), alphasum(x,y)
           Sum of sample values in the rectangle from (0,0) to (x,y), this
           allows obtaining sums of samples within a rectangle. See the
           functions without the sum postfix.

       interpolation
           Set one of interpolation methods:

           nearest, n
           bilinear, b

           Default is bilinear.

       For functions, if x and y are outside the area, the value will be
       automatically clipped to the closer edge.

       Please note that this filter can use multiple threads in which case
       each slice will have its own expression state. If you want to use only
       a single expression state because your expressions depend on previous
       state then you should limit the number of filter threads to 1.

       Examples

       o   Flip the image horizontally:

                   geq=p(W-X\,Y)

       o   Generate a bidimensional sine wave, with angle "PI/3" and a
           wavelength of 100 pixels:

                   geq=128 + 100*sin(2*(PI/100)*(cos(PI/3)*(X-50*T) + sin(PI/3)*Y)):128:128

       o   Generate a fancy enigmatic moving light:

                   nullsrc=s=256x256,geq=random(1)/hypot(X-cos(N*0.07)*W/2-W/2\,Y-sin(N*0.09)*H/2-H/2)^2*1000000*sin(N*0.02):128:128

       o   Generate a quick emboss effect:

                   format=gray,geq=lum_expr='(p(X,Y)+(256-p(X-4,Y-4)))/2'

       o   Modify RGB components depending on pixel position:

                   geq=r='X/W*r(X,Y)':g='(1-X/W)*g(X,Y)':b='(H-Y)/H*b(X,Y)'

       o   Create a radial gradient that is the same size as the input (also
           see the vignette filter):

                   geq=lum=255*gauss((X/W-0.5)*3)*gauss((Y/H-0.5)*3)/gauss(0)/gauss(0),format=gray

   gradfun
       Fix the banding artifacts that are sometimes introduced into nearly
       flat regions by truncation to 8-bit color depth.  Interpolate the
       gradients that should go where the bands are, and dither them.

       It is designed for playback only.  Do not use it prior to lossy
       compression, because compression tends to lose the dither and bring
       back the bands.

       It accepts the following parameters:

       strength
           The maximum amount by which the filter will change any one pixel.
           This is also the threshold for detecting nearly flat regions.
           Acceptable values range from .51 to 64; the default value is 1.2.
           Out-of-range values will be clipped to the valid range.

       radius
           The neighborhood to fit the gradient to. A larger radius makes for
           smoother gradients, but also prevents the filter from modifying the
           pixels near detailed regions. Acceptable values are 8-32; the
           default value is 16. Out-of-range values will be clipped to the
           valid range.

       Alternatively, the options can be specified as a flat string:
       strength[:radius]

       Examples

       o   Apply the filter with a 3.5 strength and radius of 8:

                   gradfun=3.5:8

       o   Specify radius, omitting the strength (which will fall-back to the
           default value):

                   gradfun=radius=8

   graphmonitor
       Show various filtergraph stats.

       With this filter one can debug complete filtergraph.  Especially issues
       with links filling with queued frames.

       The filter accepts the following options:

       size, s
           Set video output size. Default is hd720.

       opacity, o
           Set video opacity. Default is 0.9. Allowed range is from 0 to 1.

       mode, m
           Set output mode, can be fulll or compact.  In compact mode only
           filters with some queued frames have displayed stats.

       flags, f
           Set flags which enable which stats are shown in video.

           Available values for flags are:

           queue
               Display number of queued frames in each link.

           frame_count_in
               Display number of frames taken from filter.

           frame_count_out
               Display number of frames given out from filter.

           pts Display current filtered frame pts.

           time
               Display current filtered frame time.

           timebase
               Display time base for filter link.

           format
               Display used format for filter link.

           size
               Display video size or number of audio channels in case of audio
               used by filter link.

           rate
               Display video frame rate or sample rate in case of audio used
               by filter link.

           eof Display link output status.

       rate, r
           Set upper limit for video rate of output stream, Default value is
           25.  This guarantee that output video frame rate will not be higher
           than this value.

   greyedge
       A color constancy variation filter which estimates scene illumination
       via grey edge algorithm and corrects the scene colors accordingly.

       See: <https://staff.science.uva.nl/th.gevers/pub/GeversTIP07.pdf>

       The filter accepts the following options:

       difford
           The order of differentiation to be applied on the scene. Must be
           chosen in the range [0,2] and default value is 1.

       minknorm
           The Minkowski parameter to be used for calculating the Minkowski
           distance. Must be chosen in the range [0,20] and default value is
           1. Set to 0 for getting max value instead of calculating Minkowski
           distance.

       sigma
           The standard deviation of Gaussian blur to be applied on the scene.
           Must be chosen in the range [0,1024.0] and default value = 1.
           floor( sigma * break_off_sigma(3) ) can't be equal to 0 if difford
           is greater than 0.

       Examples

       o   Grey Edge:

                   greyedge=difford=1:minknorm=5:sigma=2

       o   Max Edge:

                   greyedge=difford=1:minknorm=0:sigma=2

   haldclut
       Apply a Hald CLUT to a video stream.

       First input is the video stream to process, and second one is the Hald
       CLUT.  The Hald CLUT input can be a simple picture or a complete video
       stream.

       The filter accepts the following options:

       shortest
           Force termination when the shortest input terminates. Default is 0.

       repeatlast
           Continue applying the last CLUT after the end of the stream. A
           value of 0 disable the filter after the last frame of the CLUT is
           reached.  Default is 1.

       "haldclut" also has the same interpolation options as lut3d (both
       filters share the same internals).

       This filter also supports the framesync options.

       More information about the Hald CLUT can be found on Eskil Steenberg's
       website (Hald CLUT author) at
       <http://www.quelsolaar.com/technology/clut.html>.

       Commands

       This filter supports the "interp" option as commands.

       Workflow examples

       Hald CLUT video stream

       Generate an identity Hald CLUT stream altered with various effects:

               ffmpeg -f lavfi -i B<haldclutsrc>=8 -vf "hue=H=2*PI*t:s=sin(2*PI*t)+1, curves=cross_process" -t 10 -c:v ffv1 clut.nut

       Note: make sure you use a lossless codec.

       Then use it with "haldclut" to apply it on some random stream:

               ffmpeg -f lavfi -i mandelbrot -i clut.nut -filter_complex '[0][1] haldclut' -t 20 mandelclut.mkv

       The Hald CLUT will be applied to the 10 first seconds (duration of
       clut.nut), then the latest picture of that CLUT stream will be applied
       to the remaining frames of the "mandelbrot" stream.

       Hald CLUT with preview

       A Hald CLUT is supposed to be a squared image of "Level*Level*Level" by
       "Level*Level*Level" pixels. For a given Hald CLUT, FFmpeg will select
       the biggest possible square starting at the top left of the picture.
       The remaining padding pixels (bottom or right) will be ignored. This
       area can be used to add a preview of the Hald CLUT.

       Typically, the following generated Hald CLUT will be supported by the
       "haldclut" filter:

               ffmpeg -f lavfi -i B<haldclutsrc>=8 -vf "
                  pad=iw+320 [padded_clut];
                  smptebars=s=320x256, split [a][b];
                  [padded_clut][a] overlay=W-320:h, curves=color_negative [main];
                  [main][b] overlay=W-320" -frames:v 1 clut.png

       It contains the original and a preview of the effect of the CLUT: SMPTE
       color bars are displayed on the right-top, and below the same color
       bars processed by the color changes.

       Then, the effect of this Hald CLUT can be visualized with:

               ffplay input.mkv -vf "movie=clut.png, [in] haldclut"

   hflip
       Flip the input video horizontally.

       For example, to horizontally flip the input video with ffmpeg:

               ffmpeg -i in.avi -vf "hflip" out.avi

   histeq
       This filter applies a global color histogram equalization on a per-
       frame basis.

       It can be used to correct video that has a compressed range of pixel
       intensities.  The filter redistributes the pixel intensities to
       equalize their distribution across the intensity range. It may be
       viewed as an "automatically adjusting contrast filter". This filter is
       useful only for correcting degraded or poorly captured source video.

       The filter accepts the following options:

       strength
           Determine the amount of equalization to be applied.  As the
           strength is reduced, the distribution of pixel intensities more-
           and-more approaches that of the input frame. The value must be a
           float number in the range [0,1] and defaults to 0.200.

       intensity
           Set the maximum intensity that can generated and scale the output
           values appropriately.  The strength should be set as desired and
           then the intensity can be limited if needed to avoid washing-out.
           The value must be a float number in the range [0,1] and defaults to
           0.210.

       antibanding
           Set the antibanding level. If enabled the filter will randomly vary
           the luminance of output pixels by a small amount to avoid banding
           of the histogram. Possible values are "none", "weak" or "strong".
           It defaults to "none".

   histogram
       Compute and draw a color distribution histogram for the input video.

       The computed histogram is a representation of the color component
       distribution in an image.

       Standard histogram displays the color components distribution in an
       image.  Displays color graph for each color component. Shows
       distribution of the Y, U, V, A or R, G, B components, depending on
       input format, in the current frame. Below each graph a color component
       scale meter is shown.

       The filter accepts the following options:

       level_height
           Set height of level. Default value is 200.  Allowed range is [50,
           2048].

       scale_height
           Set height of color scale. Default value is 12.  Allowed range is
           [0, 40].

       display_mode
           Set display mode.  It accepts the following values:

           stack
               Per color component graphs are placed below each other.

           parade
               Per color component graphs are placed side by side.

           overlay
               Presents information identical to that in the "parade", except
               that the graphs representing color components are superimposed
               directly over one another.

           Default is "stack".

       levels_mode
           Set mode. Can be either "linear", or "logarithmic".  Default is
           "linear".

       components
           Set what color components to display.  Default is 7.

       fgopacity
           Set foreground opacity. Default is 0.7.

       bgopacity
           Set background opacity. Default is 0.5.

       Examples

       o   Calculate and draw histogram:

                   ffplay -i input -vf histogram

   hqdn3d
       This is a high precision/quality 3d denoise filter. It aims to reduce
       image noise, producing smooth images and making still images really
       still. It should enhance compressibility.

       It accepts the following optional parameters:

       luma_spatial
           A non-negative floating point number which specifies spatial luma
           strength.  It defaults to 4.0.

       chroma_spatial
           A non-negative floating point number which specifies spatial chroma
           strength.  It defaults to 3.0*luma_spatial/4.0.

       luma_tmp
           A floating point number which specifies luma temporal strength. It
           defaults to 6.0*luma_spatial/4.0.

       chroma_tmp
           A floating point number which specifies chroma temporal strength.
           It defaults to luma_tmp*chroma_spatial/luma_spatial.

       Commands

       This filter supports same commands as options.  The command accepts the
       same syntax of the corresponding option.

       If the specified expression is not valid, it is kept at its current
       value.

   hwdownload
       Download hardware frames to system memory.

       The input must be in hardware frames, and the output a non-hardware
       format.  Not all formats will be supported on the output - it may be
       necessary to insert an additional format filter immediately following
       in the graph to get the output in a supported format.

   hwmap
       Map hardware frames to system memory or to another device.

       This filter has several different modes of operation; which one is used
       depends on the input and output formats:

       o   Hardware frame input, normal frame output

           Map the input frames to system memory and pass them to the output.
           If the original hardware frame is later required (for example,
           after overlaying something else on part of it), the hwmap filter
           can be used again in the next mode to retrieve it.

       o   Normal frame input, hardware frame output

           If the input is actually a software-mapped hardware frame, then
           unmap it - that is, return the original hardware frame.

           Otherwise, a device must be provided.  Create new hardware surfaces
           on that device for the output, then map them back to the software
           format at the input and give those frames to the preceding filter.
           This will then act like the hwupload filter, but may be able to
           avoid an additional copy when the input is already in a compatible
           format.

       o   Hardware frame input and output

           A device must be supplied for the output, either directly or with
           the derive_device option.  The input and output devices must be of
           different types and compatible - the exact meaning of this is
           system-dependent, but typically it means that they must refer to
           the same underlying hardware context (for example, refer to the
           same graphics card).

           If the input frames were originally created on the output device,
           then unmap to retrieve the original frames.

           Otherwise, map the frames to the output device - create new
           hardware frames on the output corresponding to the frames on the
           input.

       The following additional parameters are accepted:

       mode
           Set the frame mapping mode.  Some combination of:

           read
               The mapped frame should be readable.

           write
               The mapped frame should be writeable.

           overwrite
               The mapping will always overwrite the entire frame.

               This may improve performance in some cases, as the original
               contents of the frame need not be loaded.

           direct
               The mapping must not involve any copying.

               Indirect mappings to copies of frames are created in some cases
               where either direct mapping is not possible or it would have
               unexpected properties.  Setting this flag ensures that the
               mapping is direct and will fail if that is not possible.

           Defaults to read+write if not specified.

       derive_device type
           Rather than using the device supplied at initialisation, instead
           derive a new device of type type from the device the input frames
           exist on.

       reverse
           In a hardware to hardware mapping, map in reverse - create frames
           in the sink and map them back to the source.  This may be necessary
           in some cases where a mapping in one direction is required but only
           the opposite direction is supported by the devices being used.

           This option is dangerous - it may break the preceding filter in
           undefined ways if there are any additional constraints on that
           filter's output.  Do not use it without fully understanding the
           implications of its use.

   hwupload
       Upload system memory frames to hardware surfaces.

       The device to upload to must be supplied when the filter is
       initialised.  If using ffmpeg, select the appropriate device with the
       -filter_hw_device option or with the derive_device option.  The input
       and output devices must be of different types and compatible - the
       exact meaning of this is system-dependent, but typically it means that
       they must refer to the same underlying hardware context (for example,
       refer to the same graphics card).

       The following additional parameters are accepted:

       derive_device type
           Rather than using the device supplied at initialisation, instead
           derive a new device of type type from the device the input frames
           exist on.

   hwupload_cuda
       Upload system memory frames to a CUDA device.

       It accepts the following optional parameters:

       device
           The number of the CUDA device to use

   hqx
       Apply a high-quality magnification filter designed for pixel art. This
       filter was originally created by Maxim Stepin.

       It accepts the following option:

       n   Set the scaling dimension: 2 for "hq2x", 3 for "hq3" and 4 for
           "hq4x".  Default is 3.

   hstack
       Stack input videos horizontally.

       All streams must be of same pixel format and of same height.

       Note that this filter is faster than using overlay and pad filter to
       create same output.

       The filter accepts the following option:

       inputs
           Set number of input streams. Default is 2.

       shortest
           If set to 1, force the output to terminate when the shortest input
           terminates. Default value is 0.

   hue
       Modify the hue and/or the saturation of the input.

       It accepts the following parameters:

       h   Specify the hue angle as a number of degrees. It accepts an
           expression, and defaults to "0".

       s   Specify the saturation in the [-10,10] range. It accepts an
           expression and defaults to "1".

       H   Specify the hue angle as a number of radians. It accepts an
           expression, and defaults to "0".

       b   Specify the brightness in the [-10,10] range. It accepts an
           expression and defaults to "0".

       h and H are mutually exclusive, and can't be specified at the same
       time.

       The b, h, H and s option values are expressions containing the
       following constants:

       n   frame count of the input frame starting from 0

       pts presentation timestamp of the input frame expressed in time base
           units

       r   frame rate of the input video, NAN if the input frame rate is
           unknown

       t   timestamp expressed in seconds, NAN if the input timestamp is
           unknown

       tb  time base of the input video

       Examples

       o   Set the hue to 90 degrees and the saturation to 1.0:

                   hue=h=90:s=1

       o   Same command but expressing the hue in radians:

                   hue=H=PI/2:s=1

       o   Rotate hue and make the saturation swing between 0 and 2 over a
           period of 1 second:

                   hue="H=2*PI*t: s=sin(2*PI*t)+1"

       o   Apply a 3 seconds saturation fade-in effect starting at 0:

                   hue="s=min(t/3\,1)"

           The general fade-in expression can be written as:

                   hue="s=min(0\, max((t-START)/DURATION\, 1))"

       o   Apply a 3 seconds saturation fade-out effect starting at 5 seconds:

                   hue="s=max(0\, min(1\, (8-t)/3))"

           The general fade-out expression can be written as:

                   hue="s=max(0\, min(1\, (START+DURATION-t)/DURATION))"

       Commands

       This filter supports the following commands:

       b
       s
       h
       H   Modify the hue and/or the saturation and/or brightness of the input
           video.  The command accepts the same syntax of the corresponding
           option.

           If the specified expression is not valid, it is kept at its current
           value.

   hysteresis
       Grow first stream into second stream by connecting components.  This
       makes it possible to build more robust edge masks.

       This filter accepts the following options:

       planes
           Set which planes will be processed as bitmap, unprocessed planes
           will be copied from first stream.  By default value 0xf, all planes
           will be processed.

       threshold
           Set threshold which is used in filtering. If pixel component value
           is higher than this value filter algorithm for connecting
           components is activated.  By default value is 0.

       The "hysteresis" filter also supports the framesync options.

   identity
       Obtain the identity score between two input videos.

       This filter takes two input videos.

       Both input videos must have the same resolution and pixel format for
       this filter to work correctly. Also it assumes that both inputs have
       the same number of frames, which are compared one by one.

       The obtained per component, average, min and max identity score is
       printed through the logging system.

       The filter stores the calculated identity scores of each frame in frame
       metadata.

       In the below example the input file main.mpg being processed is
       compared with the reference file ref.mpg.

               ffmpeg -i main.mpg -i ref.mpg -lavfi identity -f null -

   idet
       Detect video interlacing type.

       This filter tries to detect if the input frames are interlaced,
       progressive, top or bottom field first. It will also try to detect
       fields that are repeated between adjacent frames (a sign of telecine).

       Single frame detection considers only immediately adjacent frames when
       classifying each frame.  Multiple frame detection incorporates the
       classification history of previous frames.

       The filter will log these metadata values:

       single.current_frame
           Detected type of current frame using single-frame detection. One
           of: ``tff'' (top field first), ``bff'' (bottom field first),
           ``progressive'', or ``undetermined''

       single.tff
           Cumulative number of frames detected as top field first using
           single-frame detection.

       multiple.tff
           Cumulative number of frames detected as top field first using
           multiple-frame detection.

       single.bff
           Cumulative number of frames detected as bottom field first using
           single-frame detection.

       multiple.current_frame
           Detected type of current frame using multiple-frame detection. One
           of: ``tff'' (top field first), ``bff'' (bottom field first),
           ``progressive'', or ``undetermined''

       multiple.bff
           Cumulative number of frames detected as bottom field first using
           multiple-frame detection.

       single.progressive
           Cumulative number of frames detected as progressive using single-
           frame detection.

       multiple.progressive
           Cumulative number of frames detected as progressive using multiple-
           frame detection.

       single.undetermined
           Cumulative number of frames that could not be classified using
           single-frame detection.

       multiple.undetermined
           Cumulative number of frames that could not be classified using
           multiple-frame detection.

       repeated.current_frame
           Which field in the current frame is repeated from the last. One of
           ``neither'', ``top'', or ``bottom''.

       repeated.neither
           Cumulative number of frames with no repeated field.

       repeated.top
           Cumulative number of frames with the top field repeated from the
           previous frame's top field.

       repeated.bottom
           Cumulative number of frames with the bottom field repeated from the
           previous frame's bottom field.

       The filter accepts the following options:

       intl_thres
           Set interlacing threshold.

       prog_thres
           Set progressive threshold.

       rep_thres
           Threshold for repeated field detection.

       half_life
           Number of frames after which a given frame's contribution to the
           statistics is halved (i.e., it contributes only 0.5 to its
           classification). The default of 0 means that all frames seen are
           given full weight of 1.0 forever.

       analyze_interlaced_flag
           When this is not 0 then idet will use the specified number of
           frames to determine if the interlaced flag is accurate, it will not
           count undetermined frames.  If the flag is found to be accurate it
           will be used without any further computations, if it is found to be
           inaccurate it will be cleared without any further computations.
           This allows inserting the idet filter as a low computational method
           to clean up the interlaced flag

   il
       Deinterleave or interleave fields.

       This filter allows one to process interlaced images fields without
       deinterlacing them. Deinterleaving splits the input frame into 2 fields
       (so called half pictures). Odd lines are moved to the top half of the
       output image, even lines to the bottom half.  You can process (filter)
       them independently and then re-interleave them.

       The filter accepts the following options:

       luma_mode, l
       chroma_mode, c
       alpha_mode, a
           Available values for luma_mode, chroma_mode and alpha_mode are:

           none
               Do nothing.

           deinterleave, d
               Deinterleave fields, placing one above the other.

           interleave, i
               Interleave fields. Reverse the effect of deinterleaving.

           Default value is "none".

       luma_swap, ls
       chroma_swap, cs
       alpha_swap, as
           Swap luma/chroma/alpha fields. Exchange even & odd lines. Default
           value is 0.

       Commands

       This filter supports the all above options as commands.

   inflate
       Apply inflate effect to the video.

       This filter replaces the pixel by the local(33) average by taking into
       account only values higher than the pixel.

       It accepts the following options:

       threshold0
       threshold1
       threshold2
       threshold3
           Limit the maximum change for each plane, default is 65535.  If 0,
           plane will remain unchanged.

       Commands

       This filter supports the all above options as commands.

   interlace
       Simple interlacing filter from progressive contents. This interleaves
       upper (or lower) lines from odd frames with lower (or upper) lines from
       even frames, halving the frame rate and preserving image height.

                  Original        Original             New Frame
                  Frame 'j'      Frame 'j+1'             (tff)
                 ==========      ===========       ==================
                   Line 0  -------------------->    Frame 'j' Line 0
                   Line 1          Line 1  ---->   Frame 'j+1' Line 1
                   Line 2 --------------------->    Frame 'j' Line 2
                   Line 3          Line 3  ---->   Frame 'j+1' Line 3
                    ...             ...                   ...
               New Frame + 1 will be generated by Frame 'j+2' and Frame 'j+3' and so on

       It accepts the following optional parameters:

       scan
           This determines whether the interlaced frame is taken from the even
           (tff - default) or odd (bff) lines of the progressive frame.

       lowpass
           Vertical lowpass filter to avoid twitter interlacing and reduce
           moire patterns.

           0, off
               Disable vertical lowpass filter

           1, linear
               Enable linear filter (default)

           2, complex
               Enable complex filter. This will slightly less reduce twitter
               and moire but better retain detail and subjective sharpness
               impression.

   kerndeint
       Deinterlace input video by applying Donald Graft's adaptive kernel
       deinterling. Work on interlaced parts of a video to produce progressive
       frames.

       The description of the accepted parameters follows.

       thresh
           Set the threshold which affects the filter's tolerance when
           determining if a pixel line must be processed. It must be an
           integer in the range [0,255] and defaults to 10. A value of 0 will
           result in applying the process on every pixels.

       map Paint pixels exceeding the threshold value to white if set to 1.
           Default is 0.

       order
           Set the fields order. Swap fields if set to 1, leave fields alone
           if 0. Default is 0.

       sharp
           Enable additional sharpening if set to 1. Default is 0.

       twoway
           Enable twoway sharpening if set to 1. Default is 0.

       Examples

       o   Apply default values:

                   kerndeint=thresh=10:map=0:order=0:sharp=0:twoway=0

       o   Enable additional sharpening:

                   kerndeint=sharp=1

       o   Paint processed pixels in white:

                   kerndeint=map=1

   kirsch
       Apply kirsch operator to input video stream.

       The filter accepts the following option:

       planes
           Set which planes will be processed, unprocessed planes will be
           copied.  By default value 0xf, all planes will be processed.

       scale
           Set value which will be multiplied with filtered result.

       delta
           Set value which will be added to filtered result.

       Commands

       This filter supports the all above options as commands.

   lagfun
       Slowly update darker pixels.

       This filter makes short flashes of light appear longer.  This filter
       accepts the following options:

       decay
           Set factor for decaying. Default is .95. Allowed range is from 0 to
           1.

       planes
           Set which planes to filter. Default is all. Allowed range is from 0
           to 15.

       Commands

       This filter supports the all above options as commands.

   lenscorrection
       Correct radial lens distortion

       This filter can be used to correct for radial distortion as can result
       from the use of wide angle lenses, and thereby re-rectify the image. To
       find the right parameters one can use tools available for example as
       part of opencv or simply trial-and-error.  To use opencv use the
       calibration sample (under samples/cpp) from the opencv sources and
       extract the k1 and k2 coefficients from the resulting matrix.

       Note that effectively the same filter is available in the open-source
       tools Krita and Digikam from the KDE project.

       In contrast to the vignette filter, which can also be used to
       compensate lens errors, this filter corrects the distortion of the
       image, whereas vignette corrects the brightness distribution, so you
       may want to use both filters together in certain cases, though you will
       have to take care of ordering, i.e. whether vignetting should be
       applied before or after lens correction.

       Options

       The filter accepts the following options:

       cx  Relative x-coordinate of the focal point of the image, and thereby
           the center of the distortion. This value has a range [0,1] and is
           expressed as fractions of the image width. Default is 0.5.

       cy  Relative y-coordinate of the focal point of the image, and thereby
           the center of the distortion. This value has a range [0,1] and is
           expressed as fractions of the image height. Default is 0.5.

       k1  Coefficient of the quadratic correction term. This value has a
           range [-1,1]. 0 means no correction. Default is 0.

       k2  Coefficient of the double quadratic correction term. This value has
           a range [-1,1].  0 means no correction. Default is 0.

       i   Set interpolation type. Can be "nearest" or "bilinear".  Default is
           "nearest".

       fc  Specify the color of the unmapped pixels. For the syntax of this
           option, check the "Color" section in the ffmpeg-utils manual.
           Default color is "black@0".

       The formula that generates the correction is:

       r_src = r_tgt * (1 + k1 * (r_tgt / r_0)^2 + k2 * (r_tgt / r_0)^4)

       where r_0 is halve of the image diagonal and r_src and r_tgt are the
       distances from the focal point in the source and target images,
       respectively.

       Commands

       This filter supports the all above options as commands.

   lensfun
       Apply lens correction via the lensfun library
       (<http://lensfun.sourceforge.net/>).

       The "lensfun" filter requires the camera make, camera model, and lens
       model to apply the lens correction. The filter will load the lensfun
       database and query it to find the corresponding camera and lens entries
       in the database. As long as these entries can be found with the given
       options, the filter can perform corrections on frames. Note that
       incomplete strings will result in the filter choosing the best match
       with the given options, and the filter will output the chosen camera
       and lens models (logged with level "info"). You must provide the make,
       camera model, and lens model as they are required.

       The filter accepts the following options:

       make
           The make of the camera (for example, "Canon"). This option is
           required.

       model
           The model of the camera (for example, "Canon EOS 100D"). This
           option is required.

       lens_model
           The model of the lens (for example, "Canon EF-S 18-55mm f/3.5-5.6
           IS STM"). This option is required.

       mode
           The type of correction to apply. The following values are valid
           options:

           vignetting
               Enables fixing lens vignetting.

           geometry
               Enables fixing lens geometry. This is the default.

           subpixel
               Enables fixing chromatic aberrations.

           vig_geo
               Enables fixing lens vignetting and lens geometry.

           vig_subpixel
               Enables fixing lens vignetting and chromatic aberrations.

           distortion
               Enables fixing both lens geometry and chromatic aberrations.

           all Enables all possible corrections.

       focal_length
           The focal length of the image/video (zoom; expected constant for
           video). For example, a 18--55mm lens has focal length range of
           [18--55], so a value in that range should be chosen when using that
           lens. Default 18.

       aperture
           The aperture of the image/video (expected constant for video). Note
           that aperture is only used for vignetting correction. Default 3.5.

       focus_distance
           The focus distance of the image/video (expected constant for
           video). Note that focus distance is only used for vignetting and
           only slightly affects the vignetting correction process. If
           unknown, leave it at the default value (which is 1000).

       scale
           The scale factor which is applied after transformation. After
           correction the video is no longer necessarily rectangular. This
           parameter controls how much of the resulting image is visible. The
           value 0 means that a value will be chosen automatically such that
           there is little or no unmapped area in the output image. 1.0 means
           that no additional scaling is done. Lower values may result in more
           of the corrected image being visible, while higher values may avoid
           unmapped areas in the output.

       target_geometry
           The target geometry of the output image/video. The following values
           are valid options:

           rectilinear (default)
           fisheye
           panoramic
           equirectangular
           fisheye_orthographic
           fisheye_stereographic
           fisheye_equisolid
           fisheye_thoby
       reverse
           Apply the reverse of image correction (instead of correcting
           distortion, apply it).

       interpolation
           The type of interpolation used when correcting distortion. The
           following values are valid options:

           nearest
           linear (default)
           lanczos

       Examples

       o   Apply lens correction with make "Canon", camera model "Canon EOS
           100D", and lens model "Canon EF-S 18-55mm f/3.5-5.6 IS STM" with
           focal length of "18" and aperture of "8.0".

                   ffmpeg -i input.mov -vf lensfun=make=Canon:model="Canon EOS 100D":lens_model="Canon EF-S 18-55mm f/3.5-5.6 IS STM":focal_length=18:aperture=8 -c:v h264 -b:v 8000k output.mov

       o   Apply the same as before, but only for the first 5 seconds of
           video.

                   ffmpeg -i input.mov -vf lensfun=make=Canon:model="Canon EOS 100D":lens_model="Canon EF-S 18-55mm f/3.5-5.6 IS STM":focal_length=18:aperture=8:enable='lte(t\,5)' -c:v h264 -b:v 8000k output.mov

   libvmaf
       Obtain the VMAF (Video Multi-Method Assessment Fusion) score between
       two input videos.

       The obtained VMAF score is printed through the logging system.

       It requires Netflix's vmaf library (libvmaf) as a pre-requisite.  After
       installing the library it can be enabled using: "./configure
       --enable-libvmaf".  If no model path is specified it uses the default
       model: "vmaf_v0.6.1.pkl".

       The filter has following options:

       model_path
           Set the model path which is to be used for SVM.  Default value:
           "/usr/local/share/model/vmaf_v0.6.1.pkl"

       log_path
           Set the file path to be used to store logs.

       log_fmt
           Set the format of the log file (csv, json or xml).

       enable_transform
           This option can enable/disable the "score_transform" applied to the
           final predicted VMAF score, if you have specified score_transform
           option in the input parameter file passed to "run_vmaf_training.py"
           Default value: "false"

       phone_model
           Invokes the phone model which will generate VMAF scores higher than
           in the regular model, which is more suitable for laptop, TV, etc.
           viewing conditions.  Default value: "false"

       psnr
           Enables computing psnr along with vmaf.  Default value: "false"

       ssim
           Enables computing ssim along with vmaf.  Default value: "false"

       ms_ssim
           Enables computing ms_ssim along with vmaf.  Default value: "false"

       pool
           Set the pool method to be used for computing vmaf.  Options are
           "min", "harmonic_mean" or "mean" (default).

       n_threads
           Set number of threads to be used when computing vmaf.  Default
           value: 0, which makes use of all available logical processors.

       n_subsample
           Set interval for frame subsampling used when computing vmaf.
           Default value: 1

       enable_conf_interval
           Enables confidence interval.  Default value: "false"

       This filter also supports the framesync options.

       Examples

       o   On the below examples the input file main.mpg being processed is
           compared with the reference file ref.mpg.

                   ffmpeg -i main.mpg -i ref.mpg -lavfi libvmaf -f null -

       o   Example with options:

                   ffmpeg -i main.mpg -i ref.mpg -lavfi libvmaf="psnr=1:log_fmt=json" -f null -

       o   Example with options and different containers:

                   ffmpeg -i main.mpg -i ref.mkv -lavfi "[0:v]settb=AVTB,setpts=PTS-STARTPTS[main];[1:v]settb=AVTB,setpts=PTS-STARTPTS[ref];[main][ref]libvmaf=psnr=1:log_fmt=json" -f null -

   limiter
       Limits the pixel components values to the specified range [min, max].

       The filter accepts the following options:

       min Lower bound. Defaults to the lowest allowed value for the input.

       max Upper bound. Defaults to the highest allowed value for the input.

       planes
           Specify which planes will be processed. Defaults to all available.

       Commands

       This filter supports the all above options as commands.

   loop
       Loop video frames.

       The filter accepts the following options:

       loop
           Set the number of loops. Setting this value to -1 will result in
           infinite loops.  Default is 0.

       size
           Set maximal size in number of frames. Default is 0.

       start
           Set first frame of loop. Default is 0.

       Examples

       o   Loop single first frame infinitely:

                   loop=loop=-1:size=1:start=0

       o   Loop single first frame 10 times:

                   loop=loop=10:size=1:start=0

       o   Loop 10 first frames 5 times:

                   loop=loop=5:size=10:start=0

   lut1d
       Apply a 1D LUT to an input video.

       The filter accepts the following options:

       file
           Set the 1D LUT file name.

           Currently supported formats:

           cube
               Iridas

           csp cineSpace

       interp
           Select interpolation mode.

           Available values are:

           nearest
               Use values from the nearest defined point.

           linear
               Interpolate values using the linear interpolation.

           cosine
               Interpolate values using the cosine interpolation.

           cubic
               Interpolate values using the cubic interpolation.

           spline
               Interpolate values using the spline interpolation.

       Commands

       This filter supports the all above options as commands.

   lut3d
       Apply a 3D LUT to an input video.

       The filter accepts the following options:

       file
           Set the 3D LUT file name.

           Currently supported formats:

           3dl AfterEffects

           cube
               Iridas

           dat DaVinci

           m3d Pandora

           csp cineSpace

       interp
           Select interpolation mode.

           Available values are:

           nearest
               Use values from the nearest defined point.

           trilinear
               Interpolate values using the 8 points defining a cube.

           tetrahedral
               Interpolate values using a tetrahedron.

           pyramid
               Interpolate values using a pyramid.

           prism
               Interpolate values using a prism.

       Commands

       This filter supports the "interp" option as commands.

   lumakey
       Turn certain luma values into transparency.

       The filter accepts the following options:

       threshold
           Set the luma which will be used as base for transparency.  Default
           value is 0.

       tolerance
           Set the range of luma values to be keyed out.  Default value is
           0.01.

       softness
           Set the range of softness. Default value is 0.  Use this to control
           gradual transition from zero to full transparency.

       Commands

       This filter supports same commands as options.  The command accepts the
       same syntax of the corresponding option.

       If the specified expression is not valid, it is kept at its current
       value.

   lut, lutrgb, lutyuv
       Compute a look-up table for binding each pixel component input value to
       an output value, and apply it to the input video.

       lutyuv applies a lookup table to a YUV input video, lutrgb to an RGB
       input video.

       These filters accept the following parameters:

       c0  set first pixel component expression

       c1  set second pixel component expression

       c2  set third pixel component expression

       c3  set fourth pixel component expression, corresponds to the alpha
           component

       r   set red component expression

       g   set green component expression

       b   set blue component expression

       a   alpha component expression

       y   set Y/luminance component expression

       u   set U/Cb component expression

       v   set V/Cr component expression

       Each of them specifies the expression to use for computing the lookup
       table for the corresponding pixel component values.

       The exact component associated to each of the c* options depends on the
       format in input.

       The lut filter requires either YUV or RGB pixel formats in input,
       lutrgb requires RGB pixel formats in input, and lutyuv requires YUV.

       The expressions can contain the following constants and functions:

       w
       h   The input width and height.

       val The input value for the pixel component.

       clipval
           The input value, clipped to the minval-maxval range.

       maxval
           The maximum value for the pixel component.

       minval
           The minimum value for the pixel component.

       negval
           The negated value for the pixel component value, clipped to the
           minval-maxval range; it corresponds to the expression
           "maxval-clipval+minval".

       clip(val)
           The computed value in val, clipped to the minval-maxval range.

       gammaval(gamma)
           The computed gamma correction value of the pixel component value,
           clipped to the minval-maxval range. It corresponds to the
           expression
           "pow((clipval-minval)/(maxval-minval)\,gamma)*(maxval-minval)+minval"

       All expressions default to "val".

       Commands

       This filter supports same commands as options.

       Examples

       o   Negate input video:

                   lutrgb="r=maxval+minval-val:g=maxval+minval-val:b=maxval+minval-val"
                   lutyuv="y=maxval+minval-val:u=maxval+minval-val:v=maxval+minval-val"

           The above is the same as:

                   lutrgb="r=negval:g=negval:b=negval"
                   lutyuv="y=negval:u=negval:v=negval"

       o   Negate luminance:

                   lutyuv=y=negval

       o   Remove chroma components, turning the video into a graytone image:

                   lutyuv="u=128:v=128"

       o   Apply a luma burning effect:

                   lutyuv="y=2*val"

       o   Remove green and blue components:

                   lutrgb="g=0:b=0"

       o   Set a constant alpha channel value on input:

                   format=rgba,lutrgb=a="maxval-minval/2"

       o   Correct luminance gamma by a factor of 0.5:

                   lutyuv=y=gammaval(0.5)

       o   Discard least significant bits of luma:

                   lutyuv=y='bitand(val, 128+64+32)'

       o   Technicolor like effect:

                   lutyuv=u='(val-maxval/2)*2+maxval/2':v='(val-maxval/2)*2+maxval/2'

   lut2, tlut2
       The "lut2" filter takes two input streams and outputs one stream.

       The "tlut2" (time lut2) filter takes two consecutive frames from one
       single stream.

       This filter accepts the following parameters:

       c0  set first pixel component expression

       c1  set second pixel component expression

       c2  set third pixel component expression

       c3  set fourth pixel component expression, corresponds to the alpha
           component

       d   set output bit depth, only available for "lut2" filter. By default
           is 0, which means bit depth is automatically picked from first
           input format.

       The "lut2" filter also supports the framesync options.

       Each of them specifies the expression to use for computing the lookup
       table for the corresponding pixel component values.

       The exact component associated to each of the c* options depends on the
       format in inputs.

       The expressions can contain the following constants:

       w
       h   The input width and height.

       x   The first input value for the pixel component.

       y   The second input value for the pixel component.

       bdx The first input video bit depth.

       bdy The second input video bit depth.

       All expressions default to "x".

       Commands

       This filter supports the all above options as commands except option
       "d".

       Examples

       o   Highlight differences between two RGB video streams:

                   lut2='ifnot(x-y,0,pow(2,bdx)-1):ifnot(x-y,0,pow(2,bdx)-1):ifnot(x-y,0,pow(2,bdx)-1)'

       o   Highlight differences between two YUV video streams:

                   lut2='ifnot(x-y,0,pow(2,bdx)-1):ifnot(x-y,pow(2,bdx-1),pow(2,bdx)-1):ifnot(x-y,pow(2,bdx-1),pow(2,bdx)-1)'

       o   Show max difference between two video streams:

                   lut2='if(lt(x,y),0,if(gt(x,y),pow(2,bdx)-1,pow(2,bdx-1))):if(lt(x,y),0,if(gt(x,y),pow(2,bdx)-1,pow(2,bdx-1))):if(lt(x,y),0,if(gt(x,y),pow(2,bdx)-1,pow(2,bdx-1)))'

   maskedclamp
       Clamp the first input stream with the second input and third input
       stream.

       Returns the value of first stream to be between second input stream -
       "undershoot" and third input stream + "overshoot".

       This filter accepts the following options:

       undershoot
           Default value is 0.

       overshoot
           Default value is 0.

       planes
           Set which planes will be processed as bitmap, unprocessed planes
           will be copied from first stream.  By default value 0xf, all planes
           will be processed.

       Commands

       This filter supports the all above options as commands.

   maskedmax
       Merge the second and third input stream into output stream using
       absolute differences between second input stream and first input stream
       and absolute difference between third input stream and first input
       stream. The picked value will be from second input stream if second
       absolute difference is greater than first one or from third input
       stream otherwise.

       This filter accepts the following options:

       planes
           Set which planes will be processed as bitmap, unprocessed planes
           will be copied from first stream.  By default value 0xf, all planes
           will be processed.

       Commands

       This filter supports the all above options as commands.

   maskedmerge
       Merge the first input stream with the second input stream using per
       pixel weights in the third input stream.

       A value of 0 in the third stream pixel component means that pixel
       component from first stream is returned unchanged, while maximum value
       (eg. 255 for 8-bit videos) means that pixel component from second
       stream is returned unchanged. Intermediate values define the amount of
       merging between both input stream's pixel components.

       This filter accepts the following options:

       planes
           Set which planes will be processed as bitmap, unprocessed planes
           will be copied from first stream.  By default value 0xf, all planes
           will be processed.

       Commands

       This filter supports the all above options as commands.

   maskedmin
       Merge the second and third input stream into output stream using
       absolute differences between second input stream and first input stream
       and absolute difference between third input stream and first input
       stream. The picked value will be from second input stream if second
       absolute difference is less than first one or from third input stream
       otherwise.

       This filter accepts the following options:

       planes
           Set which planes will be processed as bitmap, unprocessed planes
           will be copied from first stream.  By default value 0xf, all planes
           will be processed.

       Commands

       This filter supports the all above options as commands.

   maskedthreshold
       Pick pixels comparing absolute difference of two video streams with
       fixed threshold.

       If absolute difference between pixel component of first and second
       video stream is equal or lower than user supplied threshold than pixel
       component from first video stream is picked, otherwise pixel component
       from second video stream is picked.

       This filter accepts the following options:

       threshold
           Set threshold used when picking pixels from absolute difference
           from two input video streams.

       planes
           Set which planes will be processed as bitmap, unprocessed planes
           will be copied from second stream.  By default value 0xf, all
           planes will be processed.

       Commands

       This filter supports the all above options as commands.

   maskfun
       Create mask from input video.

       For example it is useful to create motion masks after "tblend" filter.

       This filter accepts the following options:

       low Set low threshold. Any pixel component lower or exact than this
           value will be set to 0.

       high
           Set high threshold. Any pixel component higher than this value will
           be set to max value allowed for current pixel format.

       planes
           Set planes to filter, by default all available planes are filtered.

       fill
           Fill all frame pixels with this value.

       sum Set max average pixel value for frame. If sum of all pixel
           components is higher that this average, output frame will be
           completely filled with value set by fill option.  Typically useful
           for scene changes when used in combination with "tblend" filter.

       Commands

       This filter supports the all above options as commands.

   mcdeint
       Apply motion-compensation deinterlacing.

       It needs one field per frame as input and must thus be used together
       with yadif=1/3 or equivalent.

       This filter accepts the following options:

       mode
           Set the deinterlacing mode.

           It accepts one of the following values:

           fast
           medium
           slow
               use iterative motion estimation

           extra_slow
               like slow, but use multiple reference frames.

           Default value is fast.

       parity
           Set the picture field parity assumed for the input video. It must
           be one of the following values:

           0, tff
               assume top field first

           1, bff
               assume bottom field first

           Default value is bff.

       qp  Set per-block quantization parameter (QP) used by the internal
           encoder.

           Higher values should result in a smoother motion vector field but
           less optimal individual vectors. Default value is 1.

   median
       Pick median pixel from certain rectangle defined by radius.

       This filter accepts the following options:

       radius
           Set horizontal radius size. Default value is 1.  Allowed range is
           integer from 1 to 127.

       planes
           Set which planes to process. Default is 15, which is all available
           planes.

       radiusV
           Set vertical radius size. Default value is 0.  Allowed range is
           integer from 0 to 127.  If it is 0, value will be picked from
           horizontal "radius" option.

       percentile
           Set median percentile. Default value is 0.5.  Default value of 0.5
           will pick always median values, while 0 will pick minimum values,
           and 1 maximum values.

       Commands

       This filter supports same commands as options.  The command accepts the
       same syntax of the corresponding option.

       If the specified expression is not valid, it is kept at its current
       value.

   mergeplanes
       Merge color channel components from several video streams.

       The filter accepts up to 4 input streams, and merge selected input
       planes to the output video.

       This filter accepts the following options:

       mapping
           Set input to output plane mapping. Default is 0.

           The mappings is specified as a bitmap. It should be specified as a
           hexadecimal number in the form 0xAa[Bb[Cc[Dd]]]. 'Aa' describes the
           mapping for the first plane of the output stream. 'A' sets the
           number of the input stream to use (from 0 to 3), and 'a' the plane
           number of the corresponding input to use (from 0 to 3). The rest of
           the mappings is similar, 'Bb' describes the mapping for the output
           stream second plane, 'Cc' describes the mapping for the output
           stream third plane and 'Dd' describes the mapping for the output
           stream fourth plane.

       format
           Set output pixel format. Default is "yuva444p".

       Examples

       o   Merge three gray video streams of same width and height into single
           video stream:

                   [a0][a1][a2]mergeplanes=0x001020:yuv444p

       o   Merge 1st yuv444p stream and 2nd gray video stream into yuva444p
           video stream:

                   [a0][a1]mergeplanes=0x00010210:yuva444p

       o   Swap Y and A plane in yuva444p stream:

                   format=yuva444p,mergeplanes=0x03010200:yuva444p

       o   Swap U and V plane in yuv420p stream:

                   format=yuv420p,mergeplanes=0x000201:yuv420p

       o   Cast a rgb24 clip to yuv444p:

                   format=rgb24,mergeplanes=0x000102:yuv444p

   mestimate
       Estimate and export motion vectors using block matching algorithms.
       Motion vectors are stored in frame side data to be used by other
       filters.

       This filter accepts the following options:

       method
           Specify the motion estimation method. Accepts one of the following
           values:

           esa Exhaustive search algorithm.

           tss Three step search algorithm.

           tdls
               Two dimensional logarithmic search algorithm.

           ntss
               New three step search algorithm.

           fss Four step search algorithm.

           ds  Diamond search algorithm.

           hexbs
               Hexagon-based search algorithm.

           epzs
               Enhanced predictive zonal search algorithm.

           umh Uneven multi-hexagon search algorithm.

           Default value is esa.

       mb_size
           Macroblock size. Default 16.

       search_param
           Search parameter. Default 7.

   midequalizer
       Apply Midway Image Equalization effect using two video streams.

       Midway Image Equalization adjusts a pair of images to have the same
       histogram, while maintaining their dynamics as much as possible. It's
       useful for e.g. matching exposures from a pair of stereo cameras.

       This filter has two inputs and one output, which must be of same pixel
       format, but may be of different sizes. The output of filter is first
       input adjusted with midway histogram of both inputs.

       This filter accepts the following option:

       planes
           Set which planes to process. Default is 15, which is all available
           planes.

   minterpolate
       Convert the video to specified frame rate using motion interpolation.

       This filter accepts the following options:

       fps Specify the output frame rate. This can be rational e.g.
           "60000/1001". Frames are dropped if fps is lower than source fps.
           Default 60.

       mi_mode
           Motion interpolation mode. Following values are accepted:

           dup Duplicate previous or next frame for interpolating new ones.

           blend
               Blend source frames. Interpolated frame is mean of previous and
               next frames.

           mci Motion compensated interpolation. Following options are
               effective when this mode is selected:

               mc_mode
                   Motion compensation mode. Following values are accepted:

                   obmc
                       Overlapped block motion compensation.

                   aobmc
                       Adaptive overlapped block motion compensation. Window
                       weighting coefficients are controlled adaptively
                       according to the reliabilities of the neighboring
                       motion vectors to reduce oversmoothing.

                   Default mode is obmc.

               me_mode
                   Motion estimation mode. Following values are accepted:

                   bidir
                       Bidirectional motion estimation. Motion vectors are
                       estimated for each source frame in both forward and
                       backward directions.

                   bilat
                       Bilateral motion estimation. Motion vectors are
                       estimated directly for interpolated frame.

                   Default mode is bilat.

               me  The algorithm to be used for motion estimation. Following
                   values are accepted:

                   esa Exhaustive search algorithm.

                   tss Three step search algorithm.

                   tdls
                       Two dimensional logarithmic search algorithm.

                   ntss
                       New three step search algorithm.

                   fss Four step search algorithm.

                   ds  Diamond search algorithm.

                   hexbs
                       Hexagon-based search algorithm.

                   epzs
                       Enhanced predictive zonal search algorithm.

                   umh Uneven multi-hexagon search algorithm.

                   Default algorithm is epzs.

               mb_size
                   Macroblock size. Default 16.

               search_param
                   Motion estimation search parameter. Default 32.

               vsbmc
                   Enable variable-size block motion compensation. Motion
                   estimation is applied with smaller block sizes at object
                   boundaries in order to make the them less blur. Default is
                   0 (disabled).

       scd Scene change detection method. Scene change leads motion vectors to
           be in random direction. Scene change detection replace interpolated
           frames by duplicate ones. May not be needed for other modes.
           Following values are accepted:

           none
               Disable scene change detection.

           fdiff
               Frame difference. Corresponding pixel values are compared and
               if it satisfies scd_threshold scene change is detected.

           Default method is fdiff.

       scd_threshold
           Scene change detection threshold. Default is 10..

   mix
       Mix several video input streams into one video stream.

       A description of the accepted options follows.

       nb_inputs
           The number of inputs. If unspecified, it defaults to 2.

       weights
           Specify weight of each input video stream as sequence.  Each weight
           is separated by space. If number of weights is smaller than number
           of frames last specified weight will be used for all remaining
           unset weights.

       scale
           Specify scale, if it is set it will be multiplied with sum of each
           weight multiplied with pixel values to give final destination pixel
           value. By default scale is auto scaled to sum of weights.

       duration
           Specify how end of stream is determined.

           longest
               The duration of the longest input. (default)

           shortest
               The duration of the shortest input.

           first
               The duration of the first input.

       Commands

       This filter supports the following commands:

       weights
       scale
           Syntax is same as option with same name.

   monochrome
       Convert video to gray using custom color filter.

       A description of the accepted options follows.

       cb  Set the chroma blue spot. Allowed range is from -1 to 1.  Default
           value is 0.

       cr  Set the chroma red spot. Allowed range is from -1 to 1.  Default
           value is 0.

       size
           Set the color filter size. Allowed range is from .1 to 10.  Default
           value is 1.

       high
           Set the highlights strength. Allowed range is from 0 to 1.  Default
           value is 0.

       Commands

       This filter supports the all above options as commands.

   mpdecimate
       Drop frames that do not differ greatly from the previous frame in order
       to reduce frame rate.

       The main use of this filter is for very-low-bitrate encoding (e.g.
       streaming over dialup modem), but it could in theory be used for fixing
       movies that were inverse-telecined incorrectly.

       A description of the accepted options follows.

       max Set the maximum number of consecutive frames which can be dropped
           (if positive), or the minimum interval between dropped frames (if
           negative). If the value is 0, the frame is dropped disregarding the
           number of previous sequentially dropped frames.

           Default value is 0.

       hi
       lo
       frac
           Set the dropping threshold values.

           Values for hi and lo are for 8x8 pixel blocks and represent actual
           pixel value differences, so a threshold of 64 corresponds to 1 unit
           of difference for each pixel, or the same spread out differently
           over the block.

           A frame is a candidate for dropping if no 8x8 blocks differ by more
           than a threshold of hi, and if no more than frac blocks (1 meaning
           the whole image) differ by more than a threshold of lo.

           Default value for hi is 64*12, default value for lo is 64*5, and
           default value for frac is 0.33.

   msad
       Obtain the MSAD (Mean Sum of Absolute Differences) between two input
       videos.

       This filter takes two input videos.

       Both input videos must have the same resolution and pixel format for
       this filter to work correctly. Also it assumes that both inputs have
       the same number of frames, which are compared one by one.

       The obtained per component, average, min and max MSAD is printed
       through the logging system.

       The filter stores the calculated MSAD of each frame in frame metadata.

       In the below example the input file main.mpg being processed is
       compared with the reference file ref.mpg.

               ffmpeg -i main.mpg -i ref.mpg -lavfi msad -f null -

   negate
       Negate (invert) the input video.

       It accepts the following option:

       negate_alpha
           With value 1, it negates the alpha component, if present. Default
           value is 0.

       Commands

       This filter supports same commands as options.

   nlmeans
       Denoise frames using Non-Local Means algorithm.

       Each pixel is adjusted by looking for other pixels with similar
       contexts. This context similarity is defined by comparing their
       surrounding patches of size pxp. Patches are searched in an area of rxr
       around the pixel.

       Note that the research area defines centers for patches, which means
       some patches will be made of pixels outside that research area.

       The filter accepts the following options.

       s   Set denoising strength. Default is 1.0. Must be in range [1.0,
           30.0].

       p   Set patch size. Default is 7. Must be odd number in range [0, 99].

       pc  Same as p but for chroma planes.

           The default value is 0 and means automatic.

       r   Set research size. Default is 15. Must be odd number in range [0,
           99].

       rc  Same as r but for chroma planes.

           The default value is 0 and means automatic.

   nnedi
       Deinterlace video using neural network edge directed interpolation.

       This filter accepts the following options:

       weights
           Mandatory option, without binary file filter can not work.
           Currently file can be found here:
           https://github.com/dubhater/vapoursynth-nnedi3/blob/master/src/nnedi3_weights.bin

       deint
           Set which frames to deinterlace, by default it is "all".  Can be
           "all" or "interlaced".

       field
           Set mode of operation.

           Can be one of the following:

           af  Use frame flags, both fields.

           a   Use frame flags, single field.

           t   Use top field only.

           b   Use bottom field only.

           tf  Use both fields, top first.

           bf  Use both fields, bottom first.

       planes
           Set which planes to process, by default filter process all frames.

       nsize
           Set size of local neighborhood around each pixel, used by the
           predictor neural network.

           Can be one of the following:

           s8x6
           s16x6
           s32x6
           s48x6
           s8x4
           s16x4
           s32x4
       nns Set the number of neurons in predictor neural network.  Can be one
           of the following:

           n16
           n32
           n64
           n128
           n256
       qual
           Controls the number of different neural network predictions that
           are blended together to compute the final output value. Can be
           "fast", default or "slow".

       etype
           Set which set of weights to use in the predictor.  Can be one of
           the following:

           a, abs
               weights trained to minimize absolute error

           s, mse
               weights trained to minimize squared error

       pscrn
           Controls whether or not the prescreener neural network is used to
           decide which pixels should be processed by the predictor neural
           network and which can be handled by simple cubic interpolation.
           The prescreener is trained to know whether cubic interpolation will
           be sufficient for a pixel or whether it should be predicted by the
           predictor nn.  The computational complexity of the prescreener nn
           is much less than that of the predictor nn. Since most pixels can
           be handled by cubic interpolation, using the prescreener generally
           results in much faster processing.  The prescreener is pretty
           accurate, so the difference between using it and not using it is
           almost always unnoticeable.

           Can be one of the following:

           none
           original
           new
           new2
           new3

           Default is "new".

       Commands

       This filter supports same commands as options, excluding weights
       option.

   noformat
       Force libavfilter not to use any of the specified pixel formats for the
       input to the next filter.

       It accepts the following parameters:

       pix_fmts
           A '|'-separated list of pixel format names, such as
           pix_fmts=yuv420p|monow|rgb24".

       Examples

       o   Force libavfilter to use a format different from yuv420p for the
           input to the vflip filter:

                   noformat=pix_fmts=yuv420p,vflip

       o   Convert the input video to any of the formats not contained in the
           list:

                   noformat=yuv420p|yuv444p|yuv410p

   noise
       Add noise on video input frame.

       The filter accepts the following options:

       all_seed
       c0_seed
       c1_seed
       c2_seed
       c3_seed
           Set noise seed for specific pixel component or all pixel components
           in case of all_seed. Default value is 123457.

       all_strength, alls
       c0_strength, c0s
       c1_strength, c1s
       c2_strength, c2s
       c3_strength, c3s
           Set noise strength for specific pixel component or all pixel
           components in case all_strength. Default value is 0. Allowed range
           is [0, 100].

       all_flags, allf
       c0_flags, c0f
       c1_flags, c1f
       c2_flags, c2f
       c3_flags, c3f
           Set pixel component flags or set flags for all components if
           all_flags.  Available values for component flags are:

           a   averaged temporal noise (smoother)

           p   mix random noise with a (semi)regular pattern

           t   temporal noise (noise pattern changes between frames)

           u   uniform noise (gaussian otherwise)

       Examples

       Add temporal and uniform noise to input video:

               noise=alls=20:allf=t+u

   normalize
       Normalize RGB video (aka histogram stretching, contrast stretching).
       See: https://en.wikipedia.org/wiki/Normalization_(image_processing)

       For each channel of each frame, the filter computes the input range and
       maps it linearly to the user-specified output range. The output range
       defaults to the full dynamic range from pure black to pure white.

       Temporal smoothing can be used on the input range to reduce flickering
       (rapid changes in brightness) caused when small dark or bright objects
       enter or leave the scene. This is similar to the auto-exposure
       (automatic gain control) on a video camera, and, like a video camera,
       it may cause a period of over- or under-exposure of the video.

       The R,G,B channels can be normalized independently, which may cause
       some color shifting, or linked together as a single channel, which
       prevents color shifting. Linked normalization preserves hue.
       Independent normalization does not, so it can be used to remove some
       color casts. Independent and linked normalization can be combined in
       any ratio.

       The normalize filter accepts the following options:

       blackpt
       whitept
           Colors which define the output range. The minimum input value is
           mapped to the blackpt. The maximum input value is mapped to the
           whitept.  The defaults are black and white respectively. Specifying
           white for blackpt and black for whitept will give color-inverted,
           normalized video. Shades of grey can be used to reduce the dynamic
           range (contrast). Specifying saturated colors here can create some
           interesting effects.

       smoothing
           The number of previous frames to use for temporal smoothing. The
           input range of each channel is smoothed using a rolling average
           over the current frame and the smoothing previous frames. The
           default is 0 (no temporal smoothing).

       independence
           Controls the ratio of independent (color shifting) channel
           normalization to linked (color preserving) normalization. 0.0 is
           fully linked, 1.0 is fully independent. Defaults to 1.0 (fully
           independent).

       strength
           Overall strength of the filter. 1.0 is full strength. 0.0 is a
           rather expensive no-op. Defaults to 1.0 (full strength).

       Commands

       This filter supports same commands as options, excluding smoothing
       option.  The command accepts the same syntax of the corresponding
       option.

       If the specified expression is not valid, it is kept at its current
       value.

       Examples

       Stretch video contrast to use the full dynamic range, with no temporal
       smoothing; may flicker depending on the source content:

               normalize=blackpt=black:whitept=white:smoothing=0

       As above, but with 50 frames of temporal smoothing; flicker should be
       reduced, depending on the source content:

               normalize=blackpt=black:whitept=white:smoothing=50

       As above, but with hue-preserving linked channel normalization:

               normalize=blackpt=black:whitept=white:smoothing=50:independence=0

       As above, but with half strength:

               normalize=blackpt=black:whitept=white:smoothing=50:independence=0:strength=0.5

       Map the darkest input color to red, the brightest input color to cyan:

               normalize=blackpt=red:whitept=cyan

   null
       Pass the video source unchanged to the output.

   ocr
       Optical Character Recognition

       This filter uses Tesseract for optical character recognition. To enable
       compilation of this filter, you need to configure FFmpeg with
       "--enable-libtesseract".

       It accepts the following options:

       datapath
           Set datapath to tesseract data. Default is to use whatever was set
           at installation.

       language
           Set language, default is "eng".

       whitelist
           Set character whitelist.

       blacklist
           Set character blacklist.

       The filter exports recognized text as the frame metadata
       "lavfi.ocr.text".  The filter exports confidence of recognized words as
       the frame metadata "lavfi.ocr.confidence".

   ocv
       Apply a video transform using libopencv.

       To enable this filter, install the libopencv library and headers and
       configure FFmpeg with "--enable-libopencv".

       It accepts the following parameters:

       filter_name
           The name of the libopencv filter to apply.

       filter_params
           The parameters to pass to the libopencv filter. If not specified,
           the default values are assumed.

       Refer to the official libopencv documentation for more precise
       information:
       <http://docs.opencv.org/master/modules/imgproc/doc/filtering.html>

       Several libopencv filters are supported; see the following subsections.

       dilate

       Dilate an image by using a specific structuring element.  It
       corresponds to the libopencv function "cvDilate".

       It accepts the parameters: struct_el|nb_iterations.

       struct_el represents a structuring element, and has the syntax:
       colsxrows+anchor_xxanchor_y/shape

       cols and rows represent the number of columns and rows of the
       structuring element, anchor_x and anchor_y the anchor point, and shape
       the shape for the structuring element. shape must be "rect", "cross",
       "ellipse", or "custom".

       If the value for shape is "custom", it must be followed by a string of
       the form "=filename". The file with name filename is assumed to
       represent a binary image, with each printable character corresponding
       to a bright pixel. When a custom shape is used, cols and rows are
       ignored, the number or columns and rows of the read file are assumed
       instead.

       The default value for struct_el is "33+0x0/rect".

       nb_iterations specifies the number of times the transform is applied to
       the image, and defaults to 1.

       Some examples:

               # Use the default values
               ocv=dilate

               # Dilate using a structuring element with a 5x5 cross, iterating two times
               ocv=filter_name=dilate:filter_params=5x5+2x2/cross|2

               # Read the shape from the file diamond.shape, iterating two times.
               # The file diamond.shape may contain a pattern of characters like this
               #   *
               #  ***
               # *****
               #  ***
               #   *
               # The specified columns and rows are ignored
               # but the anchor point coordinates are not
               ocv=dilate:0x0+2x2/custom=diamond.shape|2

       erode

       Erode an image by using a specific structuring element.  It corresponds
       to the libopencv function "cvErode".

       It accepts the parameters: struct_el:nb_iterations, with the same
       syntax and semantics as the dilate filter.

       smooth

       Smooth the input video.

       The filter takes the following parameters:
       type|param1|param2|param3|param4.

       type is the type of smooth filter to apply, and must be one of the
       following values: "blur", "blur_no_scale", "median", "gaussian", or
       "bilateral". The default value is "gaussian".

       The meaning of param1, param2, param3, and param4 depends on the smooth
       type. param1 and param2 accept integer positive values or 0. param3 and
       param4 accept floating point values.

       The default value for param1 is 3. The default value for the other
       parameters is 0.

       These parameters correspond to the parameters assigned to the libopencv
       function "cvSmooth".

   oscilloscope
       2D Video Oscilloscope.

       Useful to measure spatial impulse, step responses, chroma delays, etc.

       It accepts the following parameters:

       x   Set scope center x position.

       y   Set scope center y position.

       s   Set scope size, relative to frame diagonal.

       t   Set scope tilt/rotation.

       o   Set trace opacity.

       tx  Set trace center x position.

       ty  Set trace center y position.

       tw  Set trace width, relative to width of frame.

       th  Set trace height, relative to height of frame.

       c   Set which components to trace. By default it traces first three
           components.

       g   Draw trace grid. By default is enabled.

       st  Draw some statistics. By default is enabled.

       sc  Draw scope. By default is enabled.

       Commands

       This filter supports same commands as options.  The command accepts the
       same syntax of the corresponding option.

       If the specified expression is not valid, it is kept at its current
       value.

       Examples

       o   Inspect full first row of video frame.

                   oscilloscope=x=0.5:y=0:s=1

       o   Inspect full last row of video frame.

                   oscilloscope=x=0.5:y=1:s=1

       o   Inspect full 5th line of video frame of height 1080.

                   oscilloscope=x=0.5:y=5/1080:s=1

       o   Inspect full last column of video frame.

                   oscilloscope=x=1:y=0.5:s=1:t=1

   overlay
       Overlay one video on top of another.

       It takes two inputs and has one output. The first input is the "main"
       video on which the second input is overlaid.

       It accepts the following parameters:

       A description of the accepted options follows.

       x
       y   Set the expression for the x and y coordinates of the overlaid
           video on the main video. Default value is "0" for both expressions.
           In case the expression is invalid, it is set to a huge value
           (meaning that the overlay will not be displayed within the output
           visible area).

       eof_action
           See framesync.

       eval
           Set when the expressions for x, and y are evaluated.

           It accepts the following values:

           init
               only evaluate expressions once during the filter initialization
               or when a command is processed

           frame
               evaluate expressions for each incoming frame

           Default value is frame.

       shortest
           See framesync.

       format
           Set the format for the output video.

           It accepts the following values:

           yuv420
               force YUV420 output

           yuv420p10
               force YUV420p10 output

           yuv422
               force YUV422 output

           yuv422p10
               force YUV422p10 output

           yuv444
               force YUV444 output

           rgb force packed RGB output

           gbrp
               force planar RGB output

           auto
               automatically pick format

           Default value is yuv420.

       repeatlast
           See framesync.

       alpha
           Set format of alpha of the overlaid video, it can be straight or
           premultiplied. Default is straight.

       The x, and y expressions can contain the following parameters.

       main_w, W
       main_h, H
           The main input width and height.

       overlay_w, w
       overlay_h, h
           The overlay input width and height.

       x
       y   The computed values for x and y. They are evaluated for each new
           frame.

       hsub
       vsub
           horizontal and vertical chroma subsample values of the output
           format. For example for the pixel format "yuv422p" hsub is 2 and
           vsub is 1.

       n   the number of input frame, starting from 0

       pos the position in the file of the input frame, NAN if unknown

       t   The timestamp, expressed in seconds. It's NAN if the input
           timestamp is unknown.

       This filter also supports the framesync options.

       Note that the n, pos, t variables are available only when evaluation is
       done per frame, and will evaluate to NAN when eval is set to init.

       Be aware that frames are taken from each input video in timestamp
       order, hence, if their initial timestamps differ, it is a good idea to
       pass the two inputs through a setpts=PTS-STARTPTS filter to have them
       begin in the same zero timestamp, as the example for the movie filter
       does.

       You can chain together more overlays but you should test the efficiency
       of such approach.

       Commands

       This filter supports the following commands:

       x
       y   Modify the x and y of the overlay input.  The command accepts the
           same syntax of the corresponding option.

           If the specified expression is not valid, it is kept at its current
           value.

       Examples

       o   Draw the overlay at 10 pixels from the bottom right corner of the
           main video:

                   overlay=main_w-overlay_w-10:main_h-overlay_h-10

           Using named options the example above becomes:

                   overlay=x=main_w-overlay_w-10:y=main_h-overlay_h-10

       o   Insert a transparent PNG logo in the bottom left corner of the
           input, using the ffmpeg tool with the "-filter_complex" option:

                   ffmpeg -i input -i logo -filter_complex 'overlay=10:main_h-overlay_h-10' output

       o   Insert 2 different transparent PNG logos (second logo on bottom
           right corner) using the ffmpeg tool:

                   ffmpeg -i input -i logo1 -i logo2 -filter_complex 'overlay=x=10:y=H-h-10,overlay=x=W-w-10:y=H-h-10' output

       o   Add a transparent color layer on top of the main video; "WxH" must
           specify the size of the main input to the overlay filter:

                   color=color=red@.3:size=WxH [over]; [in][over] overlay [out]

       o   Play an original video and a filtered version (here with the
           deshake filter) side by side using the ffplay tool:

                   ffplay input.avi -vf 'split[a][b]; [a]pad=iw*2:ih[src]; [b]deshake[filt]; [src][filt]overlay=w'

           The above command is the same as:

                   ffplay input.avi -vf 'split[b], pad=iw*2[src], [b]deshake, [src]overlay=w'

       o   Make a sliding overlay appearing from the left to the right top
           part of the screen starting since time 2:

                   overlay=x='if(gte(t,2), -w+(t-2)*20, NAN)':y=0

       o   Compose output by putting two input videos side to side:

                   ffmpeg -i left.avi -i right.avi -filter_complex "
                   nullsrc=size=200x100 [background];
                   [0:v] setpts=PTS-STARTPTS, scale=100x100 [left];
                   [1:v] setpts=PTS-STARTPTS, scale=100x100 [right];
                   [background][left]       overlay=shortest=1       [background+left];
                   [background+left][right] overlay=shortest=1:x=100 [left+right]
                   "

       o   Mask 10-20 seconds of a video by applying the delogo filter to a
           section

                   ffmpeg -i test.avi -codec:v:0 wmv2 -ar 11025 -b:v 9000k
                   -vf '[in]split[split_main][split_delogo];[split_delogo]trim=start=360:end=371,delogo=0:0:640:480[delogoed];[split_main][delogoed]overlay=eof_action=pass[out]'
                   masked.avi

       o   Chain several overlays in cascade:

                   nullsrc=s=200x200 [bg];
                   testsrc=s=100x100, split=4 [in0][in1][in2][in3];
                   [in0] lutrgb=r=0, [bg]   overlay=0:0     [mid0];
                   [in1] lutrgb=g=0, [mid0] overlay=100:0   [mid1];
                   [in2] lutrgb=b=0, [mid1] overlay=0:100   [mid2];
                   [in3] null,       [mid2] overlay=100:100 [out0]

   overlay_cuda
       Overlay one video on top of another.

       This is the CUDA variant of the overlay filter.  It only accepts CUDA
       frames. The underlying input pixel formats have to match.

       It takes two inputs and has one output. The first input is the "main"
       video on which the second input is overlaid.

       It accepts the following parameters:

       x
       y   Set the x and y coordinates of the overlaid video on the main
           video.  Default value is "0" for both expressions.

       eof_action
           See framesync.

       shortest
           See framesync.

       repeatlast
           See framesync.

       This filter also supports the framesync options.

   owdenoise
       Apply Overcomplete Wavelet denoiser.

       The filter accepts the following options:

       depth
           Set depth.

           Larger depth values will denoise lower frequency components more,
           but slow down filtering.

           Must be an int in the range 8-16, default is 8.

       luma_strength, ls
           Set luma strength.

           Must be a double value in the range 0-1000, default is 1.0.

       chroma_strength, cs
           Set chroma strength.

           Must be a double value in the range 0-1000, default is 1.0.

   pad
       Add paddings to the input image, and place the original input at the
       provided x, y coordinates.

       It accepts the following parameters:

       width, w
       height, h
           Specify an expression for the size of the output image with the
           paddings added. If the value for width or height is 0, the
           corresponding input size is used for the output.

           The width expression can reference the value set by the height
           expression, and vice versa.

           The default value of width and height is 0.

       x
       y   Specify the offsets to place the input image at within the padded
           area, with respect to the top/left border of the output image.

           The x expression can reference the value set by the y expression,
           and vice versa.

           The default value of x and y is 0.

           If x or y evaluate to a negative number, they'll be changed so the
           input image is centered on the padded area.

       color
           Specify the color of the padded area. For the syntax of this
           option, check the "Color" section in the ffmpeg-utils manual.

           The default value of color is "black".

       eval
           Specify when to evaluate  width, height, x and y expression.

           It accepts the following values:

           init
               Only evaluate expressions once during the filter initialization
               or when a command is processed.

           frame
               Evaluate expressions for each incoming frame.

           Default value is init.

       aspect
           Pad to aspect instead to a resolution.

       The value for the width, height, x, and y options are expressions
       containing the following constants:

       in_w
       in_h
           The input video width and height.

       iw
       ih  These are the same as in_w and in_h.

       out_w
       out_h
           The output width and height (the size of the padded area), as
           specified by the width and height expressions.

       ow
       oh  These are the same as out_w and out_h.

       x
       y   The x and y offsets as specified by the x and y expressions, or NAN
           if not yet specified.

       a   same as iw / ih

       sar input sample aspect ratio

       dar input display aspect ratio, it is the same as (iw / ih) * sar

       hsub
       vsub
           The horizontal and vertical chroma subsample values. For example
           for the pixel format "yuv422p" hsub is 2 and vsub is 1.

       Examples

       o   Add paddings with the color "violet" to the input video. The output
           video size is 640x480, and the top-left corner of the input video
           is placed at column 0, row 40

                   pad=640:480:0:40:violet

           The example above is equivalent to the following command:

                   pad=width=640:height=480:x=0:y=40:color=violet

       o   Pad the input to get an output with dimensions increased by 3/2,
           and put the input video at the center of the padded area:

                   pad="3/2*iw:3/2*ih:(ow-iw)/2:(oh-ih)/2"

       o   Pad the input to get a squared output with size equal to the
           maximum value between the input width and height, and put the input
           video at the center of the padded area:

                   pad="max(iw\,ih):ow:(ow-iw)/2:(oh-ih)/2"

       o   Pad the input to get a final w/h ratio of 16:9:

                   pad="ih*16/9:ih:(ow-iw)/2:(oh-ih)/2"

       o   In case of anamorphic video, in order to set the output display
           aspect correctly, it is necessary to use sar in the expression,
           according to the relation:

                   (ih * X / ih) * sar = output_dar
                   X = output_dar / sar

           Thus the previous example needs to be modified to:

                   pad="ih*16/9/sar:ih:(ow-iw)/2:(oh-ih)/2"

       o   Double the output size and put the input video in the bottom-right
           corner of the output padded area:

                   pad="2*iw:2*ih:ow-iw:oh-ih"

   palettegen
       Generate one palette for a whole video stream.

       It accepts the following options:

       max_colors
           Set the maximum number of colors to quantize in the palette.  Note:
           the palette will still contain 256 colors; the unused palette
           entries will be black.

       reserve_transparent
           Create a palette of 255 colors maximum and reserve the last one for
           transparency. Reserving the transparency color is useful for GIF
           optimization.  If not set, the maximum of colors in the palette
           will be 256. You probably want to disable this option for a
           standalone image.  Set by default.

       transparency_color
           Set the color that will be used as background for transparency.

       stats_mode
           Set statistics mode.

           It accepts the following values:

           full
               Compute full frame histograms.

           diff
               Compute histograms only for the part that differs from previous
               frame. This might be relevant to give more importance to the
               moving part of your input if the background is static.

           single
               Compute new histogram for each frame.

           Default value is full.

       The filter also exports the frame metadata "lavfi.color_quant_ratio"
       ("nb_color_in / nb_color_out") which you can use to evaluate the degree
       of color quantization of the palette. This information is also visible
       at info logging level.

       Examples

       o   Generate a representative palette of a given video using ffmpeg:

                   ffmpeg -i input.mkv -vf palettegen palette.png

   paletteuse
       Use a palette to downsample an input video stream.

       The filter takes two inputs: one video stream and a palette. The
       palette must be a 256 pixels image.

       It accepts the following options:

       dither
           Select dithering mode. Available algorithms are:

           bayer
               Ordered 8x8 bayer dithering (deterministic)

           heckbert
               Dithering as defined by Paul Heckbert in 1982 (simple error
               diffusion).  Note: this dithering is sometimes considered
               "wrong" and is included as a reference.

           floyd_steinberg
               Floyd and Steingberg dithering (error diffusion)

           sierra2
               Frankie Sierra dithering v2 (error diffusion)

           sierra2_4a
               Frankie Sierra dithering v2 "Lite" (error diffusion)

           Default is sierra2_4a.

       bayer_scale
           When bayer dithering is selected, this option defines the scale of
           the pattern (how much the crosshatch pattern is visible). A low
           value means more visible pattern for less banding, and higher value
           means less visible pattern at the cost of more banding.

           The option must be an integer value in the range [0,5]. Default is
           2.

       diff_mode
           If set, define the zone to process

           rectangle
               Only the changing rectangle will be reprocessed. This is
               similar to GIF cropping/offsetting compression mechanism. This
               option can be useful for speed if only a part of the image is
               changing, and has use cases such as limiting the scope of the
               error diffusal dither to the rectangle that bounds the moving
               scene (it leads to more deterministic output if the scene
               doesn't change much, and as a result less moving noise and
               better GIF compression).

           Default is none.

       new Take new palette for each output frame.

       alpha_threshold
           Sets the alpha threshold for transparency. Alpha values above this
           threshold will be treated as completely opaque, and values below
           this threshold will be treated as completely transparent.

           The option must be an integer value in the range [0,255]. Default
           is 128.

       Examples

       o   Use a palette (generated for example with palettegen) to encode a
           GIF using ffmpeg:

                   ffmpeg -i input.mkv -i palette.png -lavfi paletteuse output.gif

   perspective
       Correct perspective of video not recorded perpendicular to the screen.

       A description of the accepted parameters follows.

       x0
       y0
       x1
       y1
       x2
       y2
       x3
       y3  Set coordinates expression for top left, top right, bottom left and
           bottom right corners.  Default values are "0:0:W:0:0:H:W:H" with
           which perspective will remain unchanged.  If the "sense" option is
           set to "source", then the specified points will be sent to the
           corners of the destination. If the "sense" option is set to
           "destination", then the corners of the source will be sent to the
           specified coordinates.

           The expressions can use the following variables:

           W
           H   the width and height of video frame.

           in  Input frame count.

           on  Output frame count.

       interpolation
           Set interpolation for perspective correction.

           It accepts the following values:

           linear
           cubic

           Default value is linear.

       sense
           Set interpretation of coordinate options.

           It accepts the following values:

           0, source
               Send point in the source specified by the given coordinates to
               the corners of the destination.

           1, destination
               Send the corners of the source to the point in the destination
               specified by the given coordinates.

               Default value is source.

       eval
           Set when the expressions for coordinates x0,y0,...x3,y3 are
           evaluated.

           It accepts the following values:

           init
               only evaluate expressions once during the filter initialization
               or when a command is processed

           frame
               evaluate expressions for each incoming frame

           Default value is init.

   phase
       Delay interlaced video by one field time so that the field order
       changes.

       The intended use is to fix PAL movies that have been captured with the
       opposite field order to the film-to-video transfer.

       A description of the accepted parameters follows.

       mode
           Set phase mode.

           It accepts the following values:

           t   Capture field order top-first, transfer bottom-first.  Filter
               will delay the bottom field.

           b   Capture field order bottom-first, transfer top-first.  Filter
               will delay the top field.

           p   Capture and transfer with the same field order. This mode only
               exists for the documentation of the other options to refer to,
               but if you actually select it, the filter will faithfully do
               nothing.

           a   Capture field order determined automatically by field flags,
               transfer opposite.  Filter selects among t and b modes on a
               frame by frame basis using field flags. If no field information
               is available, then this works just like u.

           u   Capture unknown or varying, transfer opposite.  Filter selects
               among t and b on a frame by frame basis by analyzing the images
               and selecting the alternative that produces best match between
               the fields.

           T   Capture top-first, transfer unknown or varying.  Filter selects
               among t and p using image analysis.

           B   Capture bottom-first, transfer unknown or varying.  Filter
               selects among b and p using image analysis.

           A   Capture determined by field flags, transfer unknown or varying.
               Filter selects among t, b and p using field flags and image
               analysis. If no field information is available, then this works
               just like U. This is the default mode.

           U   Both capture and transfer unknown or varying.  Filter selects
               among t, b and p using image analysis only.

       Commands

       This filter supports the all above options as commands.

   photosensitivity
       Reduce various flashes in video, so to help users with epilepsy.

       It accepts the following options:

       frames, f
           Set how many frames to use when filtering. Default is 30.

       threshold, t
           Set detection threshold factor. Default is 1.  Lower is stricter.

       skip
           Set how many pixels to skip when sampling frames. Default is 1.
           Allowed range is from 1 to 1024.

       bypass
           Leave frames unchanged. Default is disabled.

   pixdesctest
       Pixel format descriptor test filter, mainly useful for internal
       testing. The output video should be equal to the input video.

       For example:

               format=monow, pixdesctest

       can be used to test the monowhite pixel format descriptor definition.

   pixscope
       Display sample values of color channels. Mainly useful for checking
       color and levels. Minimum supported resolution is 640x480.

       The filters accept the following options:

       x   Set scope X position, relative offset on X axis.

       y   Set scope Y position, relative offset on Y axis.

       w   Set scope width.

       h   Set scope height.

       o   Set window opacity. This window also holds statistics about pixel
           area.

       wx  Set window X position, relative offset on X axis.

       wy  Set window Y position, relative offset on Y axis.

       Commands

       This filter supports same commands as options.

   pp
       Enable the specified chain of postprocessing subfilters using
       libpostproc. This library should be automatically selected with a GPL
       build ("--enable-gpl").  Subfilters must be separated by '/' and can be
       disabled by prepending a '-'.  Each subfilter and some options have a
       short and a long name that can be used interchangeably, i.e. dr/dering
       are the same.

       The filters accept the following options:

       subfilters
           Set postprocessing subfilters string.

       All subfilters share common options to determine their scope:

       a/autoq
           Honor the quality commands for this subfilter.

       c/chrom
           Do chrominance filtering, too (default).

       y/nochrom
           Do luminance filtering only (no chrominance).

       n/noluma
           Do chrominance filtering only (no luminance).

       These options can be appended after the subfilter name, separated by a
       '|'.

       Available subfilters are:

       hb/hdeblock[|difference[|flatness]]
           Horizontal deblocking filter

           difference
               Difference factor where higher values mean more deblocking
               (default: 32).

           flatness
               Flatness threshold where lower values mean more deblocking
               (default: 39).

       vb/vdeblock[|difference[|flatness]]
           Vertical deblocking filter

           difference
               Difference factor where higher values mean more deblocking
               (default: 32).

           flatness
               Flatness threshold where lower values mean more deblocking
               (default: 39).

       ha/hadeblock[|difference[|flatness]]
           Accurate horizontal deblocking filter

           difference
               Difference factor where higher values mean more deblocking
               (default: 32).

           flatness
               Flatness threshold where lower values mean more deblocking
               (default: 39).

       va/vadeblock[|difference[|flatness]]
           Accurate vertical deblocking filter

           difference
               Difference factor where higher values mean more deblocking
               (default: 32).

           flatness
               Flatness threshold where lower values mean more deblocking
               (default: 39).

       The horizontal and vertical deblocking filters share the difference and
       flatness values so you cannot set different horizontal and vertical
       thresholds.

       h1/x1hdeblock
           Experimental horizontal deblocking filter

       v1/x1vdeblock
           Experimental vertical deblocking filter

       dr/dering
           Deringing filter

       tn/tmpnoise[|threshold1[|threshold2[|threshold3]]], temporal noise
       reducer
           threshold1
               larger -> stronger filtering

           threshold2
               larger -> stronger filtering

           threshold3
               larger -> stronger filtering

       al/autolevels[:f/fullyrange], automatic brightness / contrast
       correction
           f/fullyrange
               Stretch luminance to "0-255".

       lb/linblenddeint
           Linear blend deinterlacing filter that deinterlaces the given block
           by filtering all lines with a "(1 2 1)" filter.

       li/linipoldeint
           Linear interpolating deinterlacing filter that deinterlaces the
           given block by linearly interpolating every second line.

       ci/cubicipoldeint
           Cubic interpolating deinterlacing filter deinterlaces the given
           block by cubically interpolating every second line.

       md/mediandeint
           Median deinterlacing filter that deinterlaces the given block by
           applying a median filter to every second line.

       fd/ffmpegdeint
           FFmpeg deinterlacing filter that deinterlaces the given block by
           filtering every second line with a "(-1 4 2 4 -1)" filter.

       l5/lowpass5
           Vertically applied FIR lowpass deinterlacing filter that
           deinterlaces the given block by filtering all lines with a "(-1 2 6
           2 -1)" filter.

       fq/forceQuant[|quantizer]
           Overrides the quantizer table from the input with the constant
           quantizer you specify.

           quantizer
               Quantizer to use

       de/default
           Default pp filter combination ("hb|a,vb|a,dr|a")

       fa/fast
           Fast pp filter combination ("h1|a,v1|a,dr|a")

       ac  High quality pp filter combination ("ha|a|128|7,va|a,dr|a")

       Examples

       o   Apply horizontal and vertical deblocking, deringing and automatic
           brightness/contrast:

                   pp=hb/vb/dr/al

       o   Apply default filters without brightness/contrast correction:

                   pp=de/-al

       o   Apply default filters and temporal denoiser:

                   pp=default/tmpnoise|1|2|3

       o   Apply deblocking on luminance only, and switch vertical deblocking
           on or off automatically depending on available CPU time:

                   pp=hb|y/vb|a

   pp7
       Apply Postprocessing filter 7. It is variant of the spp filter, similar
       to spp = 6 with 7 point DCT, where only the center sample is used after
       IDCT.

       The filter accepts the following options:

       qp  Force a constant quantization parameter. It accepts an integer in
           range 0 to 63. If not set, the filter will use the QP from the
           video stream (if available).

       mode
           Set thresholding mode. Available modes are:

           hard
               Set hard thresholding.

           soft
               Set soft thresholding (better de-ringing effect, but likely
               blurrier).

           medium
               Set medium thresholding (good results, default).

   premultiply
       Apply alpha premultiply effect to input video stream using first plane
       of second stream as alpha.

       Both streams must have same dimensions and same pixel format.

       The filter accepts the following option:

       planes
           Set which planes will be processed, unprocessed planes will be
           copied.  By default value 0xf, all planes will be processed.

       inplace
           Do not require 2nd input for processing, instead use alpha plane
           from input stream.

   prewitt
       Apply prewitt operator to input video stream.

       The filter accepts the following option:

       planes
           Set which planes will be processed, unprocessed planes will be
           copied.  By default value 0xf, all planes will be processed.

       scale
           Set value which will be multiplied with filtered result.

       delta
           Set value which will be added to filtered result.

       Commands

       This filter supports the all above options as commands.

   pseudocolor
       Alter frame colors in video with pseudocolors.

       This filter accepts the following options:

       c0  set pixel first component expression

       c1  set pixel second component expression

       c2  set pixel third component expression

       c3  set pixel fourth component expression, corresponds to the alpha
           component

       index, i
           set component to use as base for altering colors

       preset, p
           Pick one of built-in LUTs. By default is set to none.

           Available LUTs:

           magma
           inferno
           plasma
           viridis
           turbo
           cividis
           range1
           range2
           shadows
           highlights
       opacity
           Set opacity of output colors. Allowed range is from 0 to 1.
           Default value is set to 1.

       Each of the expression options specifies the expression to use for
       computing the lookup table for the corresponding pixel component
       values.

       The expressions can contain the following constants and functions:

       w
       h   The input width and height.

       val The input value for the pixel component.

       ymin, umin, vmin, amin
           The minimum allowed component value.

       ymax, umax, vmax, amax
           The maximum allowed component value.

       All expressions default to "val".

       Commands

       This filter supports the all above options as commands.

       Examples

       o   Change too high luma values to gradient:

                   pseudocolor="'if(between(val,ymax,amax),lerp(ymin,ymax,(val-ymax)/(amax-ymax)),-1):if(between(val,ymax,amax),lerp(umax,umin,(val-ymax)/(amax-ymax)),-1):if(between(val,ymax,amax),lerp(vmin,vmax,(val-ymax)/(amax-ymax)),-1):-1'"

   psnr
       Obtain the average, maximum and minimum PSNR (Peak Signal to Noise
       Ratio) between two input videos.

       This filter takes in input two input videos, the first input is
       considered the "main" source and is passed unchanged to the output. The
       second input is used as a "reference" video for computing the PSNR.

       Both video inputs must have the same resolution and pixel format for
       this filter to work correctly. Also it assumes that both inputs have
       the same number of frames, which are compared one by one.

       The obtained average PSNR is printed through the logging system.

       The filter stores the accumulated MSE (mean squared error) of each
       frame, and at the end of the processing it is averaged across all
       frames equally, and the following formula is applied to obtain the
       PSNR:

               PSNR = 10*log10(MAX^2/MSE)

       Where MAX is the average of the maximum values of each component of the
       image.

       The description of the accepted parameters follows.

       stats_file, f
           If specified the filter will use the named file to save the PSNR of
           each individual frame. When filename equals "-" the data is sent to
           standard output.

       stats_version
           Specifies which version of the stats file format to use. Details of
           each format are written below.  Default value is 1.

       stats_add_max
           Determines whether the max value is output to the stats log.
           Default value is 0.  Requires stats_version >= 2. If this is set
           and stats_version < 2, the filter will return an error.

       This filter also supports the framesync options.

       The file printed if stats_file is selected, contains a sequence of
       key/value pairs of the form key:value for each compared couple of
       frames.

       If a stats_version greater than 1 is specified, a header line precedes
       the list of per-frame-pair stats, with key value pairs following the
       frame format with the following parameters:

       psnr_log_version
           The version of the log file format. Will match stats_version.

       fields
           A comma separated list of the per-frame-pair parameters included in
           the log.

       A description of each shown per-frame-pair parameter follows:

       n   sequential number of the input frame, starting from 1

       mse_avg
           Mean Square Error pixel-by-pixel average difference of the compared
           frames, averaged over all the image components.

       mse_y, mse_u, mse_v, mse_r, mse_g, mse_b, mse_a
           Mean Square Error pixel-by-pixel average difference of the compared
           frames for the component specified by the suffix.

       psnr_y, psnr_u, psnr_v, psnr_r, psnr_g, psnr_b, psnr_a
           Peak Signal to Noise ratio of the compared frames for the component
           specified by the suffix.

       max_avg, max_y, max_u, max_v
           Maximum allowed value for each channel, and average over all
           channels.

       Examples

       o   For example:

                   movie=ref_movie.mpg, setpts=PTS-STARTPTS [main];
                   [main][ref] psnr="stats_file=stats.log" [out]

           On this example the input file being processed is compared with the
           reference file ref_movie.mpg. The PSNR of each individual frame is
           stored in stats.log.

       o   Another example with different containers:

                   ffmpeg -i main.mpg -i ref.mkv -lavfi  "[0:v]settb=AVTB,setpts=PTS-STARTPTS[main];[1:v]settb=AVTB,setpts=PTS-STARTPTS[ref];[main][ref]psnr" -f null -

   pullup
       Pulldown reversal (inverse telecine) filter, capable of handling mixed
       hard-telecine, 24000/1001 fps progressive, and 30000/1001 fps
       progressive content.

       The pullup filter is designed to take advantage of future context in
       making its decisions. This filter is stateless in the sense that it
       does not lock onto a pattern to follow, but it instead looks forward to
       the following fields in order to identify matches and rebuild
       progressive frames.

       To produce content with an even framerate, insert the fps filter after
       pullup, use "fps=24000/1001" if the input frame rate is 29.97fps,
       "fps=24" for 30fps and the (rare) telecined 25fps input.

       The filter accepts the following options:

       jl
       jr
       jt
       jb  These options set the amount of "junk" to ignore at the left,
           right, top, and bottom of the image, respectively. Left and right
           are in units of 8 pixels, while top and bottom are in units of 2
           lines.  The default is 8 pixels on each side.

       sb  Set the strict breaks. Setting this option to 1 will reduce the
           chances of filter generating an occasional mismatched frame, but it
           may also cause an excessive number of frames to be dropped during
           high motion sequences.  Conversely, setting it to -1 will make
           filter match fields more easily.  This may help processing of video
           where there is slight blurring between the fields, but may also
           cause there to be interlaced frames in the output.  Default value
           is 0.

       mp  Set the metric plane to use. It accepts the following values:

           l   Use luma plane.

           u   Use chroma blue plane.

           v   Use chroma red plane.

           This option may be set to use chroma plane instead of the default
           luma plane for doing filter's computations. This may improve
           accuracy on very clean source material, but more likely will
           decrease accuracy, especially if there is chroma noise (rainbow
           effect) or any grayscale video.  The main purpose of setting mp to
           a chroma plane is to reduce CPU load and make pullup usable in
           realtime on slow machines.

       For best results (without duplicated frames in the output file) it is
       necessary to change the output frame rate. For example, to inverse
       telecine NTSC input:

               ffmpeg -i input -vf pullup -r 24000/1001 ...

   qp
       Change video quantization parameters (QP).

       The filter accepts the following option:

       qp  Set expression for quantization parameter.

       The expression is evaluated through the eval API and can contain, among
       others, the following constants:

       known
           1 if index is not 129, 0 otherwise.

       qp  Sequential index starting from -129 to 128.

       Examples

       o   Some equation like:

                   qp=2+2*sin(PI*qp)

   random
       Flush video frames from internal cache of frames into a random order.
       No frame is discarded.  Inspired by frei0r nervous filter.

       frames
           Set size in number of frames of internal cache, in range from 2 to
           512. Default is 30.

       seed
           Set seed for random number generator, must be an integer included
           between 0 and "UINT32_MAX". If not specified, or if explicitly set
           to less than 0, the filter will try to use a good random seed on a
           best effort basis.

   readeia608
       Read closed captioning (EIA-608) information from the top lines of a
       video frame.

       This filter adds frame metadata for "lavfi.readeia608.X.cc" and
       "lavfi.readeia608.X.line", where "X" is the number of the identified
       line with EIA-608 data (starting from 0). A description of each
       metadata value follows:

       lavfi.readeia608.X.cc
           The two bytes stored as EIA-608 data (printed in hexadecimal).

       lavfi.readeia608.X.line
           The number of the line on which the EIA-608 data was identified and
           read.

       This filter accepts the following options:

       scan_min
           Set the line to start scanning for EIA-608 data. Default is 0.

       scan_max
           Set the line to end scanning for EIA-608 data. Default is 29.

       spw Set the ratio of width reserved for sync code detection.  Default
           is 0.27. Allowed range is "[0.1 - 0.7]".

       chp Enable checking the parity bit. In the event of a parity error, the
           filter will output 0x00 for that character. Default is false.

       lp  Lowpass lines prior to further processing. Default is enabled.

       Commands

       This filter supports the all above options as commands.

       Examples

       o   Output a csv with presentation time and the first two lines of
           identified EIA-608 captioning data.

                   ffprobe -f lavfi -i movie=captioned_video.mov,readeia608 -show_entries frame=pkt_pts_time:frame_tags=lavfi.readeia608.0.cc,lavfi.readeia608.1.cc -of csv

   readvitc
       Read vertical interval timecode (VITC) information from the top lines
       of a video frame.

       The filter adds frame metadata key "lavfi.readvitc.tc_str" with the
       timecode value, if a valid timecode has been detected. Further metadata
       key "lavfi.readvitc.found" is set to 0/1 depending on whether timecode
       data has been found or not.

       This filter accepts the following options:

       scan_max
           Set the maximum number of lines to scan for VITC data. If the value
           is set to "-1" the full video frame is scanned. Default is 45.

       thr_b
           Set the luma threshold for black. Accepts float numbers in the
           range [0.0,1.0], default value is 0.2. The value must be equal or
           less than "thr_w".

       thr_w
           Set the luma threshold for white. Accepts float numbers in the
           range [0.0,1.0], default value is 0.6. The value must be equal or
           greater than "thr_b".

       Examples

       o   Detect and draw VITC data onto the video frame; if no valid VITC is
           detected, draw "--:--:--:--" as a placeholder:

                   ffmpeg -i input.avi -filter:v 'readvitc,drawtext=fontfile=FreeMono.ttf:text=%{metadata\\:lavfi.readvitc.tc_str\\:--\\\\\\:--\\\\\\:--\\\\\\:--}:x=(w-tw)/2:y=400-ascent'

   remap
       Remap pixels using 2nd: Xmap and 3rd: Ymap input video stream.

       Destination pixel at position (X, Y) will be picked from source (x, y)
       position where x = Xmap(X, Y) and y = Ymap(X, Y). If mapping values are
       out of range, zero value for pixel will be used for destination pixel.

       Xmap and Ymap input video streams must be of same dimensions. Output
       video stream will have Xmap/Ymap video stream dimensions.  Xmap and
       Ymap input video streams are 16bit depth, single channel.

       format
           Specify pixel format of output from this filter. Can be "color" or
           "gray".  Default is "color".

       fill
           Specify the color of the unmapped pixels. For the syntax of this
           option, check the "Color" section in the ffmpeg-utils manual.
           Default color is "black".

   removegrain
       The removegrain filter is a spatial denoiser for progressive video.

       m0  Set mode for the first plane.

       m1  Set mode for the second plane.

       m2  Set mode for the third plane.

       m3  Set mode for the fourth plane.

       Range of mode is from 0 to 24. Description of each mode follows:

       0   Leave input plane unchanged. Default.

       1   Clips the pixel with the minimum and maximum of the 8 neighbour
           pixels.

       2   Clips the pixel with the second minimum and maximum of the 8
           neighbour pixels.

       3   Clips the pixel with the third minimum and maximum of the 8
           neighbour pixels.

       4   Clips the pixel with the fourth minimum and maximum of the 8
           neighbour pixels.  This is equivalent to a median filter.

       5   Line-sensitive clipping giving the minimal change.

       6   Line-sensitive clipping, intermediate.

       7   Line-sensitive clipping, intermediate.

       8   Line-sensitive clipping, intermediate.

       9   Line-sensitive clipping on a line where the neighbours pixels are
           the closest.

       10  Replaces the target pixel with the closest neighbour.

       11  [1 2 1] horizontal and vertical kernel blur.

       12  Same as mode 11.

       13  Bob mode, interpolates top field from the line where the neighbours
           pixels are the closest.

       14  Bob mode, interpolates bottom field from the line where the
           neighbours pixels are the closest.

       15  Bob mode, interpolates top field. Same as 13 but with a more
           complicated interpolation formula.

       16  Bob mode, interpolates bottom field. Same as 14 but with a more
           complicated interpolation formula.

       17  Clips the pixel with the minimum and maximum of respectively the
           maximum and minimum of each pair of opposite neighbour pixels.

       18  Line-sensitive clipping using opposite neighbours whose greatest
           distance from the current pixel is minimal.

       19  Replaces the pixel with the average of its 8 neighbours.

       20  Averages the 9 pixels ([1 1 1] horizontal and vertical blur).

       21  Clips pixels using the averages of opposite neighbour.

       22  Same as mode 21 but simpler and faster.

       23  Small edge and halo removal, but reputed useless.

       24  Similar as 23.

   removelogo
       Suppress a TV station logo, using an image file to determine which
       pixels comprise the logo. It works by filling in the pixels that
       comprise the logo with neighboring pixels.

       The filter accepts the following options:

       filename, f
           Set the filter bitmap file, which can be any image format supported
           by libavformat. The width and height of the image file must match
           those of the video stream being processed.

       Pixels in the provided bitmap image with a value of zero are not
       considered part of the logo, non-zero pixels are considered part of the
       logo. If you use white (255) for the logo and black (0) for the rest,
       you will be safe. For making the filter bitmap, it is recommended to
       take a screen capture of a black frame with the logo visible, and then
       using a threshold filter followed by the erode filter once or twice.

       If needed, little splotches can be fixed manually. Remember that if
       logo pixels are not covered, the filter quality will be much reduced.
       Marking too many pixels as part of the logo does not hurt as much, but
       it will increase the amount of blurring needed to cover over the image
       and will destroy more information than necessary, and extra pixels will
       slow things down on a large logo.

   repeatfields
       This filter uses the repeat_field flag from the Video ES headers and
       hard repeats fields based on its value.

   reverse
       Reverse a video clip.

       Warning: This filter requires memory to buffer the entire clip, so
       trimming is suggested.

       Examples

       o   Take the first 5 seconds of a clip, and reverse it.

                   trim=end=5,reverse

   rgbashift
       Shift R/G/B/A pixels horizontally and/or vertically.

       The filter accepts the following options:

       rh  Set amount to shift red horizontally.

       rv  Set amount to shift red vertically.

       gh  Set amount to shift green horizontally.

       gv  Set amount to shift green vertically.

       bh  Set amount to shift blue horizontally.

       bv  Set amount to shift blue vertically.

       ah  Set amount to shift alpha horizontally.

       av  Set amount to shift alpha vertically.

       edge
           Set edge mode, can be smear, default, or warp.

       Commands

       This filter supports the all above options as commands.

   roberts
       Apply roberts cross operator to input video stream.

       The filter accepts the following option:

       planes
           Set which planes will be processed, unprocessed planes will be
           copied.  By default value 0xf, all planes will be processed.

       scale
           Set value which will be multiplied with filtered result.

       delta
           Set value which will be added to filtered result.

       Commands

       This filter supports the all above options as commands.

   rotate
       Rotate video by an arbitrary angle expressed in radians.

       The filter accepts the following options:

       A description of the optional parameters follows.

       angle, a
           Set an expression for the angle by which to rotate the input video
           clockwise, expressed as a number of radians. A negative value will
           result in a counter-clockwise rotation. By default it is set to
           "0".

           This expression is evaluated for each frame.

       out_w, ow
           Set the output width expression, default value is "iw".  This
           expression is evaluated just once during configuration.

       out_h, oh
           Set the output height expression, default value is "ih".  This
           expression is evaluated just once during configuration.

       bilinear
           Enable bilinear interpolation if set to 1, a value of 0 disables
           it. Default value is 1.

       fillcolor, c
           Set the color used to fill the output area not covered by the
           rotated image. For the general syntax of this option, check the
           "Color" section in the ffmpeg-utils manual.  If the special value
           "none" is selected then no background is printed (useful for
           example if the background is never shown).

           Default value is "black".

       The expressions for the angle and the output size can contain the
       following constants and functions:

       n   sequential number of the input frame, starting from 0. It is always
           NAN before the first frame is filtered.

       t   time in seconds of the input frame, it is set to 0 when the filter
           is configured. It is always NAN before the first frame is filtered.

       hsub
       vsub
           horizontal and vertical chroma subsample values. For example for
           the pixel format "yuv422p" hsub is 2 and vsub is 1.

       in_w, iw
       in_h, ih
           the input video width and height

       out_w, ow
       out_h, oh
           the output width and height, that is the size of the padded area as
           specified by the width and height expressions

       rotw(a)
       roth(a)
           the minimal width/height required for completely containing the
           input video rotated by a radians.

           These are only available when computing the out_w and out_h
           expressions.

       Examples

       o   Rotate the input by PI/6 radians clockwise:

                   rotate=PI/6

       o   Rotate the input by PI/6 radians counter-clockwise:

                   rotate=-PI/6

       o   Rotate the input by 45 degrees clockwise:

                   rotate=45*PI/180

       o   Apply a constant rotation with period T, starting from an angle of
           PI/3:

                   rotate=PI/3+2*PI*t/T

       o   Make the input video rotation oscillating with a period of T
           seconds and an amplitude of A radians:

                   rotate=A*sin(2*PI/T*t)

       o   Rotate the video, output size is chosen so that the whole rotating
           input video is always completely contained in the output:

                   rotate='2*PI*t:ow=hypot(iw,ih):oh=ow'

       o   Rotate the video, reduce the output size so that no background is
           ever shown:

                   rotate=2*PI*t:ow='min(iw,ih)/sqrt(2)':oh=ow:c=none

       Commands

       The filter supports the following commands:

       a, angle
           Set the angle expression.  The command accepts the same syntax of
           the corresponding option.

           If the specified expression is not valid, it is kept at its current
           value.

   sab
       Apply Shape Adaptive Blur.

       The filter accepts the following options:

       luma_radius, lr
           Set luma blur filter strength, must be a value in range 0.1-4.0,
           default value is 1.0. A greater value will result in a more blurred
           image, and in slower processing.

       luma_pre_filter_radius, lpfr
           Set luma pre-filter radius, must be a value in the 0.1-2.0 range,
           default value is 1.0.

       luma_strength, ls
           Set luma maximum difference between pixels to still be considered,
           must be a value in the 0.1-100.0 range, default value is 1.0.

       chroma_radius, cr
           Set chroma blur filter strength, must be a value in range -0.9-4.0.
           A greater value will result in a more blurred image, and in slower
           processing.

       chroma_pre_filter_radius, cpfr
           Set chroma pre-filter radius, must be a value in the -0.9-2.0
           range.

       chroma_strength, cs
           Set chroma maximum difference between pixels to still be
           considered, must be a value in the -0.9-100.0 range.

       Each chroma option value, if not explicitly specified, is set to the
       corresponding luma option value.

   scale
       Scale (resize) the input video, using the libswscale library.

       The scale filter forces the output display aspect ratio to be the same
       of the input, by changing the output sample aspect ratio.

       If the input image format is different from the format requested by the
       next filter, the scale filter will convert the input to the requested
       format.

       Options

       The filter accepts the following options, or any of the options
       supported by the libswscale scaler.

       See the ffmpeg-scaler manual for the complete list of scaler options.

       width, w
       height, h
           Set the output video dimension expression. Default value is the
           input dimension.

           If the width or w value is 0, the input width is used for the
           output. If the height or h value is 0, the input height is used for
           the output.

           If one and only one of the values is -n with n >= 1, the scale
           filter will use a value that maintains the aspect ratio of the
           input image, calculated from the other specified dimension. After
           that it will, however, make sure that the calculated dimension is
           divisible by n and adjust the value if necessary.

           If both values are -n with n >= 1, the behavior will be identical
           to both values being set to 0 as previously detailed.

           See below for the list of accepted constants for use in the
           dimension expression.

       eval
           Specify when to evaluate width and height expression. It accepts
           the following values:

           init
               Only evaluate expressions once during the filter initialization
               or when a command is processed.

           frame
               Evaluate expressions for each incoming frame.

           Default value is init.

       interl
           Set the interlacing mode. It accepts the following values:

           1   Force interlaced aware scaling.

           0   Do not apply interlaced scaling.

           -1  Select interlaced aware scaling depending on whether the source
               frames are flagged as interlaced or not.

           Default value is 0.

       flags
           Set libswscale scaling flags. See the ffmpeg-scaler manual for the
           complete list of values. If not explicitly specified the filter
           applies the default flags.

       param0, param1
           Set libswscale input parameters for scaling algorithms that need
           them. See the ffmpeg-scaler manual for the complete documentation.
           If not explicitly specified the filter applies empty parameters.

       size, s
           Set the video size. For the syntax of this option, check the "Video
           size" section in the ffmpeg-utils manual.

       in_color_matrix
       out_color_matrix
           Set in/output YCbCr color space type.

           This allows the autodetected value to be overridden as well as
           allows forcing a specific value used for the output and encoder.

           If not specified, the color space type depends on the pixel format.

           Possible values:

           auto
               Choose automatically.

           bt709
               Format conforming to International Telecommunication Union
               (ITU) Recommendation BT.709.

           fcc Set color space conforming to the United States Federal
               Communications Commission (FCC) Code of Federal Regulations
               (CFR) Title 47 (2003) 73.682 (a).

           bt601
           bt470
           smpte170m
               Set color space conforming to:

               o   ITU Radiocommunication Sector (ITU-R) Recommendation BT.601

               o   ITU-R Rec. BT.470-6 (1998) Systems B, B1, and G

               o   Society of Motion Picture and Television Engineers (SMPTE)
                   ST 170:2004

           smpte240m
               Set color space conforming to SMPTE ST 240:1999.

           bt2020
               Set color space conforming to ITU-R BT.2020 non-constant
               luminance system.

       in_range
       out_range
           Set in/output YCbCr sample range.

           This allows the autodetected value to be overridden as well as
           allows forcing a specific value used for the output and encoder. If
           not specified, the range depends on the pixel format. Possible
           values:

           auto/unknown
               Choose automatically.

           jpeg/full/pc
               Set full range (0-255 in case of 8-bit luma).

           mpeg/limited/tv
               Set "MPEG" range (16-235 in case of 8-bit luma).

       force_original_aspect_ratio
           Enable decreasing or increasing output video width or height if
           necessary to keep the original aspect ratio. Possible values:

           disable
               Scale the video as specified and disable this feature.

           decrease
               The output video dimensions will automatically be decreased if
               needed.

           increase
               The output video dimensions will automatically be increased if
               needed.

           One useful instance of this option is that when you know a specific
           device's maximum allowed resolution, you can use this to limit the
           output video to that, while retaining the aspect ratio. For
           example, device A allows 1280x720 playback, and your video is
           1920x800. Using this option (set it to decrease) and specifying
           1280x720 to the command line makes the output 1280x533.

           Please note that this is a different thing than specifying -1 for w
           or h, you still need to specify the output resolution for this
           option to work.

       force_divisible_by
           Ensures that both the output dimensions, width and height, are
           divisible by the given integer when used together with
           force_original_aspect_ratio. This works similar to using "-n" in
           the w and h options.

           This option respects the value set for force_original_aspect_ratio,
           increasing or decreasing the resolution accordingly. The video's
           aspect ratio may be slightly modified.

           This option can be handy if you need to have a video fit within or
           exceed a defined resolution using force_original_aspect_ratio but
           also have encoder restrictions on width or height divisibility.

       The values of the w and h options are expressions containing the
       following constants:

       in_w
       in_h
           The input width and height

       iw
       ih  These are the same as in_w and in_h.

       out_w
       out_h
           The output (scaled) width and height

       ow
       oh  These are the same as out_w and out_h

       a   The same as iw / ih

       sar input sample aspect ratio

       dar The input display aspect ratio. Calculated from "(iw / ih) * sar".

       hsub
       vsub
           horizontal and vertical input chroma subsample values. For example
           for the pixel format "yuv422p" hsub is 2 and vsub is 1.

       ohsub
       ovsub
           horizontal and vertical output chroma subsample values. For example
           for the pixel format "yuv422p" hsub is 2 and vsub is 1.

       n   The (sequential) number of the input frame, starting from 0.  Only
           available with "eval=frame".

       t   The presentation timestamp of the input frame, expressed as a
           number of seconds. Only available with "eval=frame".

       pos The position (byte offset) of the frame in the input stream, or NaN
           if this information is unavailable and/or meaningless (for example
           in case of synthetic video).  Only available with "eval=frame".

       Examples

       o   Scale the input video to a size of 200x100

                   scale=w=200:h=100

           This is equivalent to:

                   scale=200:100

           or:

                   scale=200x100

       o   Specify a size abbreviation for the output size:

                   scale=qcif

           which can also be written as:

                   scale=size=qcif

       o   Scale the input to 2x:

                   scale=w=2*iw:h=2*ih

       o   The above is the same as:

                   scale=2*in_w:2*in_h

       o   Scale the input to 2x with forced interlaced scaling:

                   scale=2*iw:2*ih:interl=1

       o   Scale the input to half size:

                   scale=w=iw/2:h=ih/2

       o   Increase the width, and set the height to the same size:

                   scale=3/2*iw:ow

       o   Seek Greek harmony:

                   scale=iw:1/PHI*iw
                   scale=ih*PHI:ih

       o   Increase the height, and set the width to 3/2 of the height:

                   scale=w=3/2*oh:h=3/5*ih

       o   Increase the size, making the size a multiple of the chroma
           subsample values:

                   scale="trunc(3/2*iw/hsub)*hsub:trunc(3/2*ih/vsub)*vsub"

       o   Increase the width to a maximum of 500 pixels, keeping the same
           aspect ratio as the input:

                   scale=w='min(500\, iw*3/2):h=-1'

       o   Make pixels square by combining scale and setsar:

                   scale='trunc(ih*dar):ih',setsar=1/1

       o   Make pixels square by combining scale and setsar, making sure the
           resulting resolution is even (required by some codecs):

                   scale='trunc(ih*dar/2)*2:trunc(ih/2)*2',setsar=1/1

       Commands

       This filter supports the following commands:

       width, w
       height, h
           Set the output video dimension expression.  The command accepts the
           same syntax of the corresponding option.

           If the specified expression is not valid, it is kept at its current
           value.

   scale_npp
       Use the NVIDIA Performance Primitives (libnpp) to perform scaling
       and/or pixel format conversion on CUDA video frames. Setting the output
       width and height works in the same way as for the scale filter.

       The following additional options are accepted:

       format
           The pixel format of the output CUDA frames. If set to the string
           "same" (the default), the input format will be kept. Note that
           automatic format negotiation and conversion is not yet supported
           for hardware frames

       interp_algo
           The interpolation algorithm used for resizing. One of the
           following:

           nn  Nearest neighbour.

           linear
           cubic
           cubic2p_bspline
               2-parameter cubic (B=1, C=0)

           cubic2p_catmullrom
               2-parameter cubic (B=0, C=1/2)

           cubic2p_b05c03
               2-parameter cubic (B=1/2, C=3/10)

           super
               Supersampling

           lanczos
       force_original_aspect_ratio
           Enable decreasing or increasing output video width or height if
           necessary to keep the original aspect ratio. Possible values:

           disable
               Scale the video as specified and disable this feature.

           decrease
               The output video dimensions will automatically be decreased if
               needed.

           increase
               The output video dimensions will automatically be increased if
               needed.

           One useful instance of this option is that when you know a specific
           device's maximum allowed resolution, you can use this to limit the
           output video to that, while retaining the aspect ratio. For
           example, device A allows 1280x720 playback, and your video is
           1920x800. Using this option (set it to decrease) and specifying
           1280x720 to the command line makes the output 1280x533.

           Please note that this is a different thing than specifying -1 for w
           or h, you still need to specify the output resolution for this
           option to work.

       force_divisible_by
           Ensures that both the output dimensions, width and height, are
           divisible by the given integer when used together with
           force_original_aspect_ratio. This works similar to using "-n" in
           the w and h options.

           This option respects the value set for force_original_aspect_ratio,
           increasing or decreasing the resolution accordingly. The video's
           aspect ratio may be slightly modified.

           This option can be handy if you need to have a video fit within or
           exceed a defined resolution using force_original_aspect_ratio but
           also have encoder restrictions on width or height divisibility.

   scale2ref
       Scale (resize) the input video, based on a reference video.

       See the scale filter for available options, scale2ref supports the same
       but uses the reference video instead of the main input as basis.
       scale2ref also supports the following additional constants for the w
       and h options:

       main_w
       main_h
           The main input video's width and height

       main_a
           The same as main_w / main_h

       main_sar
           The main input video's sample aspect ratio

       main_dar, mdar
           The main input video's display aspect ratio. Calculated from
           "(main_w / main_h) * main_sar".

       main_hsub
       main_vsub
           The main input video's horizontal and vertical chroma subsample
           values.  For example for the pixel format "yuv422p" hsub is 2 and
           vsub is 1.

       main_n
           The (sequential) number of the main input frame, starting from 0.
           Only available with "eval=frame".

       main_t
           The presentation timestamp of the main input frame, expressed as a
           number of seconds. Only available with "eval=frame".

       main_pos
           The position (byte offset) of the frame in the main input stream,
           or NaN if this information is unavailable and/or meaningless (for
           example in case of synthetic video).  Only available with
           "eval=frame".

       Examples

       o   Scale a subtitle stream (b) to match the main video (a) in size
           before overlaying

                   'scale2ref[b][a];[a][b]overlay'

       o   Scale a logo to 1/10th the height of a video, while preserving its
           display aspect ratio.

                   [logo-in][video-in]scale2ref=w=oh*mdar:h=ih/10[logo-out][video-out]

       Commands

       This filter supports the following commands:

       width, w
       height, h
           Set the output video dimension expression.  The command accepts the
           same syntax of the corresponding option.

           If the specified expression is not valid, it is kept at its current
           value.

   scroll
       Scroll input video horizontally and/or vertically by constant speed.

       The filter accepts the following options:

       horizontal, h
           Set the horizontal scrolling speed. Default is 0. Allowed range is
           from -1 to 1.  Negative values changes scrolling direction.

       vertical, v
           Set the vertical scrolling speed. Default is 0. Allowed range is
           from -1 to 1.  Negative values changes scrolling direction.

       hpos
           Set the initial horizontal scrolling position. Default is 0.
           Allowed range is from 0 to 1.

       vpos
           Set the initial vertical scrolling position. Default is 0. Allowed
           range is from 0 to 1.

       Commands

       This filter supports the following commands:

       horizontal, h
           Set the horizontal scrolling speed.

       vertical, v
           Set the vertical scrolling speed.

   scdet
       Detect video scene change.

       This filter sets frame metadata with mafd between frame, the scene
       score, and forward the frame to the next filter, so they can use these
       metadata to detect scene change or others.

       In addition, this filter logs a message and sets frame metadata when it
       detects a scene change by threshold.

       "lavfi.scd.mafd" metadata keys are set with mafd for every frame.

       "lavfi.scd.score" metadata keys are set with scene change score for
       every frame to detect scene change.

       "lavfi.scd.time" metadata keys are set with current filtered frame time
       which detect scene change with threshold.

       The filter accepts the following options:

       threshold, t
           Set the scene change detection threshold as a percentage of maximum
           change. Good values are in the "[8.0, 14.0]" range. The range for
           threshold is "[0., 100.]".

           Default value is 10..

       sc_pass, s
           Set the flag to pass scene change frames to the next filter.
           Default value is 0 You can enable it if you want to get snapshot of
           scene change frames only.

   selectivecolor
       Adjust cyan, magenta, yellow and black (CMYK) to certain ranges of
       colors (such as "reds", "yellows", "greens", "cyans", ...). The
       adjustment range is defined by the "purity" of the color (that is, how
       saturated it already is).

       This filter is similar to the Adobe Photoshop Selective Color tool.

       The filter accepts the following options:

       correction_method
           Select color correction method.

           Available values are:

           absolute
               Specified adjustments are applied "as-is" (added/subtracted to
               original pixel component value).

           relative
               Specified adjustments are relative to the original component
               value.

           Default is "absolute".

       reds
           Adjustments for red pixels (pixels where the red component is the
           maximum)

       yellows
           Adjustments for yellow pixels (pixels where the blue component is
           the minimum)

       greens
           Adjustments for green pixels (pixels where the green component is
           the maximum)

       cyans
           Adjustments for cyan pixels (pixels where the red component is the
           minimum)

       blues
           Adjustments for blue pixels (pixels where the blue component is the
           maximum)

       magentas
           Adjustments for magenta pixels (pixels where the green component is
           the minimum)

       whites
           Adjustments for white pixels (pixels where all components are
           greater than 128)

       neutrals
           Adjustments for all pixels except pure black and pure white

       blacks
           Adjustments for black pixels (pixels where all components are
           lesser than 128)

       psfile
           Specify a Photoshop selective color file (".asv") to import the
           settings from.

       All the adjustment settings (reds, yellows, ...) accept up to 4 space
       separated floating point adjustment values in the [-1,1] range,
       respectively to adjust the amount of cyan, magenta, yellow and black
       for the pixels of its range.

       Examples

       o   Increase cyan by 50% and reduce yellow by 33% in every green areas,
           and increase magenta by 27% in blue areas:

                   selectivecolor=greens=.5 0 -.33 0:blues=0 .27

       o   Use a Photoshop selective color preset:

                   selectivecolor=psfile=MySelectiveColorPresets/Misty.asv

   separatefields
       The "separatefields" takes a frame-based video input and splits each
       frame into its components fields, producing a new half height clip with
       twice the frame rate and twice the frame count.

       This filter use field-dominance information in frame to decide which of
       each pair of fields to place first in the output.  If it gets it wrong
       use setfield filter before "separatefields" filter.

   setdar, setsar
       The "setdar" filter sets the Display Aspect Ratio for the filter output
       video.

       This is done by changing the specified Sample (aka Pixel) Aspect Ratio,
       according to the following equation:

               <DAR> = <HORIZONTAL_RESOLUTION> / <VERTICAL_RESOLUTION> * <SAR>

       Keep in mind that the "setdar" filter does not modify the pixel
       dimensions of the video frame. Also, the display aspect ratio set by
       this filter may be changed by later filters in the filterchain, e.g. in
       case of scaling or if another "setdar" or a "setsar" filter is applied.

       The "setsar" filter sets the Sample (aka Pixel) Aspect Ratio for the
       filter output video.

       Note that as a consequence of the application of this filter, the
       output display aspect ratio will change according to the equation
       above.

       Keep in mind that the sample aspect ratio set by the "setsar" filter
       may be changed by later filters in the filterchain, e.g. if another
       "setsar" or a "setdar" filter is applied.

       It accepts the following parameters:

       r, ratio, dar ("setdar" only), sar ("setsar" only)
           Set the aspect ratio used by the filter.

           The parameter can be a floating point number string, an expression,
           or a string of the form num:den, where num and den are the
           numerator and denominator of the aspect ratio. If the parameter is
           not specified, it is assumed the value "0".  In case the form
           "num:den" is used, the ":" character should be escaped.

       max Set the maximum integer value to use for expressing numerator and
           denominator when reducing the expressed aspect ratio to a rational.
           Default value is 100.

       The parameter sar is an expression containing the following constants:

       E, PI, PHI
           These are approximated values for the mathematical constants e
           (Euler's number), pi (Greek pi), and phi (the golden ratio).

       w, h
           The input width and height.

       a   These are the same as w / h.

       sar The input sample aspect ratio.

       dar The input display aspect ratio. It is the same as (w / h) * sar.

       hsub, vsub
           Horizontal and vertical chroma subsample values. For example, for
           the pixel format "yuv422p" hsub is 2 and vsub is 1.

       Examples

       o   To change the display aspect ratio to 16:9, specify one of the
           following:

                   setdar=dar=1.77777
                   setdar=dar=16/9

       o   To change the sample aspect ratio to 10:11, specify:

                   setsar=sar=10/11

       o   To set a display aspect ratio of 16:9, and specify a maximum
           integer value of 1000 in the aspect ratio reduction, use the
           command:

                   setdar=ratio=16/9:max=1000

   setfield
       Force field for the output video frame.

       The "setfield" filter marks the interlace type field for the output
       frames. It does not change the input frame, but only sets the
       corresponding property, which affects how the frame is treated by
       following filters (e.g. "fieldorder" or "yadif").

       The filter accepts the following options:

       mode
           Available values are:

           auto
               Keep the same field property.

           bff Mark the frame as bottom-field-first.

           tff Mark the frame as top-field-first.

           prog
               Mark the frame as progressive.

   setparams
       Force frame parameter for the output video frame.

       The "setparams" filter marks interlace and color range for the output
       frames. It does not change the input frame, but only sets the
       corresponding property, which affects how the frame is treated by
       filters/encoders.

       field_mode
           Available values are:

           auto
               Keep the same field property (default).

           bff Mark the frame as bottom-field-first.

           tff Mark the frame as top-field-first.

           prog
               Mark the frame as progressive.

       range
           Available values are:

           auto
               Keep the same color range property (default).

           unspecified, unknown
               Mark the frame as unspecified color range.

           limited, tv, mpeg
               Mark the frame as limited range.

           full, pc, jpeg
               Mark the frame as full range.

       color_primaries
           Set the color primaries.  Available values are:

           auto
               Keep the same color primaries property (default).

           bt709
           unknown
           bt470m
           bt470bg
           smpte170m
           smpte240m
           film
           bt2020
           smpte428
           smpte431
           smpte432
           jedec-p22
       color_trc
           Set the color transfer.  Available values are:

           auto
               Keep the same color trc property (default).

           bt709
           unknown
           bt470m
           bt470bg
           smpte170m
           smpte240m
           linear
           log100
           log316
           iec61966-2-4
           bt1361e
           iec61966-2-1
           bt2020-10
           bt2020-12
           smpte2084
           smpte428
           arib-std-b67
       colorspace
           Set the colorspace.  Available values are:

           auto
               Keep the same colorspace property (default).

           gbr
           bt709
           unknown
           fcc
           bt470bg
           smpte170m
           smpte240m
           ycgco
           bt2020nc
           bt2020c
           smpte2085
           chroma-derived-nc
           chroma-derived-c
           ictcp

   shear
       Apply shear transform to input video.

       This filter supports the following options:

       shx Shear factor in X-direction. Default value is 0.  Allowed range is
           from -2 to 2.

       shy Shear factor in Y-direction. Default value is 0.  Allowed range is
           from -2 to 2.

       fillcolor, c
           Set the color used to fill the output area not covered by the
           transformed video. For the general syntax of this option, check the
           "Color" section in the ffmpeg-utils manual.  If the special value
           "none" is selected then no background is printed (useful for
           example if the background is never shown).

           Default value is "black".

       interp
           Set interpolation type. Can be "bilinear" or "nearest". Default is
           "bilinear".

       Commands

       This filter supports the all above options as commands.

   showinfo
       Show a line containing various information for each input video frame.
       The input video is not modified.

       This filter supports the following options:

       checksum
           Calculate checksums of each plane. By default enabled.

       The shown line contains a sequence of key/value pairs of the form
       key:value.

       The following values are shown in the output:

       n   The (sequential) number of the input frame, starting from 0.

       pts The Presentation TimeStamp of the input frame, expressed as a
           number of time base units. The time base unit depends on the filter
           input pad.

       pts_time
           The Presentation TimeStamp of the input frame, expressed as a
           number of seconds.

       pos The position of the frame in the input stream, or -1 if this
           information is unavailable and/or meaningless (for example in case
           of synthetic video).

       fmt The pixel format name.

       sar The sample aspect ratio of the input frame, expressed in the form
           num/den.

       s   The size of the input frame. For the syntax of this option, check
           the "Video size" section in the ffmpeg-utils manual.

       i   The type of interlaced mode ("P" for "progressive", "T" for top
           field first, "B" for bottom field first).

       iskey
           This is 1 if the frame is a key frame, 0 otherwise.

       type
           The picture type of the input frame ("I" for an I-frame, "P" for a
           P-frame, "B" for a B-frame, or "?" for an unknown type).  Also
           refer to the documentation of the "AVPictureType" enum and of the
           "av_get_picture_type_char" function defined in libavutil/avutil.h.

       checksum
           The Adler-32 checksum (printed in hexadecimal) of all the planes of
           the input frame.

       plane_checksum
           The Adler-32 checksum (printed in hexadecimal) of each plane of the
           input frame, expressed in the form "[c0 c1 c2 c3]".

       mean
           The mean value of pixels in each plane of the input frame,
           expressed in the form "[mean0 mean1 mean2 mean3]".

       stdev
           The standard deviation of pixel values in each plane of the input
           frame, expressed in the form "[stdev0 stdev1 stdev2 stdev3]".

   showpalette
       Displays the 256 colors palette of each frame. This filter is only
       relevant for pal8 pixel format frames.

       It accepts the following option:

       s   Set the size of the box used to represent one palette color entry.
           Default is 30 (for a "30x30" pixel box).

   shuffleframes
       Reorder and/or duplicate and/or drop video frames.

       It accepts the following parameters:

       mapping
           Set the destination indexes of input frames.  This is space or '|'
           separated list of indexes that maps input frames to output frames.
           Number of indexes also sets maximal value that each index may have.
           '-1' index have special meaning and that is to drop frame.

       The first frame has the index 0. The default is to keep the input
       unchanged.

       Examples

       o   Swap second and third frame of every three frames of the input:

                   ffmpeg -i INPUT -vf "shuffleframes=0 2 1" OUTPUT

       o   Swap 10th and 1st frame of every ten frames of the input:

                   ffmpeg -i INPUT -vf "shuffleframes=9 1 2 3 4 5 6 7 8 0" OUTPUT

   shufflepixels
       Reorder pixels in video frames.

       This filter accepts the following options:

       direction, d
           Set shuffle direction. Can be forward or inverse direction.
           Default direction is forward.

       mode, m
           Set shuffle mode. Can be horizontal, vertical or block mode.

       width, w
       height, h
           Set shuffle block_size. In case of horizontal shuffle mode only
           width part of size is used, and in case of vertical shuffle mode
           only height part of size is used.

       seed, s
           Set random seed used with shuffling pixels. Mainly useful to set to
           be able to reverse filtering process to get original input.  For
           example, to reverse forward shuffle you need to use same parameters
           and exact same seed and to set direction to inverse.

   shuffleplanes
       Reorder and/or duplicate video planes.

       It accepts the following parameters:

       map0
           The index of the input plane to be used as the first output plane.

       map1
           The index of the input plane to be used as the second output plane.

       map2
           The index of the input plane to be used as the third output plane.

       map3
           The index of the input plane to be used as the fourth output plane.

       The first plane has the index 0. The default is to keep the input
       unchanged.

       Examples

       o   Swap the second and third planes of the input:

                   ffmpeg -i INPUT -vf shuffleplanes=0:2:1:3 OUTPUT

   signalstats
       Evaluate various visual metrics that assist in determining issues
       associated with the digitization of analog video media.

       By default the filter will log these metadata values:

       YMIN
           Display the minimal Y value contained within the input frame.
           Expressed in range of [0-255].

       YLOW
           Display the Y value at the 10% percentile within the input frame.
           Expressed in range of [0-255].

       YAVG
           Display the average Y value within the input frame. Expressed in
           range of [0-255].

       YHIGH
           Display the Y value at the 90% percentile within the input frame.
           Expressed in range of [0-255].

       YMAX
           Display the maximum Y value contained within the input frame.
           Expressed in range of [0-255].

       UMIN
           Display the minimal U value contained within the input frame.
           Expressed in range of [0-255].

       ULOW
           Display the U value at the 10% percentile within the input frame.
           Expressed in range of [0-255].

       UAVG
           Display the average U value within the input frame. Expressed in
           range of [0-255].

       UHIGH
           Display the U value at the 90% percentile within the input frame.
           Expressed in range of [0-255].

       UMAX
           Display the maximum U value contained within the input frame.
           Expressed in range of [0-255].

       VMIN
           Display the minimal V value contained within the input frame.
           Expressed in range of [0-255].

       VLOW
           Display the V value at the 10% percentile within the input frame.
           Expressed in range of [0-255].

       VAVG
           Display the average V value within the input frame. Expressed in
           range of [0-255].

       VHIGH
           Display the V value at the 90% percentile within the input frame.
           Expressed in range of [0-255].

       VMAX
           Display the maximum V value contained within the input frame.
           Expressed in range of [0-255].

       SATMIN
           Display the minimal saturation value contained within the input
           frame.  Expressed in range of [0-~181.02].

       SATLOW
           Display the saturation value at the 10% percentile within the input
           frame.  Expressed in range of [0-~181.02].

       SATAVG
           Display the average saturation value within the input frame.
           Expressed in range of [0-~181.02].

       SATHIGH
           Display the saturation value at the 90% percentile within the input
           frame.  Expressed in range of [0-~181.02].

       SATMAX
           Display the maximum saturation value contained within the input
           frame.  Expressed in range of [0-~181.02].

       HUEMED
           Display the median value for hue within the input frame. Expressed
           in range of [0-360].

       HUEAVG
           Display the average value for hue within the input frame. Expressed
           in range of [0-360].

       YDIF
           Display the average of sample value difference between all values
           of the Y plane in the current frame and corresponding values of the
           previous input frame.  Expressed in range of [0-255].

       UDIF
           Display the average of sample value difference between all values
           of the U plane in the current frame and corresponding values of the
           previous input frame.  Expressed in range of [0-255].

       VDIF
           Display the average of sample value difference between all values
           of the V plane in the current frame and corresponding values of the
           previous input frame.  Expressed in range of [0-255].

       YBITDEPTH
           Display bit depth of Y plane in current frame.  Expressed in range
           of [0-16].

       UBITDEPTH
           Display bit depth of U plane in current frame.  Expressed in range
           of [0-16].

       VBITDEPTH
           Display bit depth of V plane in current frame.  Expressed in range
           of [0-16].

       The filter accepts the following options:

       stat
       out stat specify an additional form of image analysis.  out output
           video with the specified type of pixel highlighted.

           Both options accept the following values:

           tout
               Identify temporal outliers pixels. A temporal outlier is a
               pixel unlike the neighboring pixels of the same field. Examples
               of temporal outliers include the results of video dropouts,
               head clogs, or tape tracking issues.

           vrep
               Identify vertical line repetition. Vertical line repetition
               includes similar rows of pixels within a frame. In born-digital
               video vertical line repetition is common, but this pattern is
               uncommon in video digitized from an analog source. When it
               occurs in video that results from the digitization of an analog
               source it can indicate concealment from a dropout compensator.

           brng
               Identify pixels that fall outside of legal broadcast range.

       color, c
           Set the highlight color for the out option. The default color is
           yellow.

       Examples

       o   Output data of various video metrics:

                   ffprobe -f lavfi movie=example.mov,signalstats="stat=tout+vrep+brng" -show_frames

       o   Output specific data about the minimum and maximum values of the Y
           plane per frame:

                   ffprobe -f lavfi movie=example.mov,signalstats -show_entries frame_tags=lavfi.signalstats.YMAX,lavfi.signalstats.YMIN

       o   Playback video while highlighting pixels that are outside of
           broadcast range in red.

                   ffplay example.mov -vf signalstats="out=brng:color=red"

       o   Playback video with signalstats metadata drawn over the frame.

                   ffplay example.mov -vf signalstats=stat=brng+vrep+tout,drawtext=fontfile=FreeSerif.ttf:textfile=signalstat_drawtext.txt

           The contents of signalstat_drawtext.txt used in the command are:

                   time %{pts:hms}
                   Y (%{metadata:lavfi.signalstats.YMIN}-%{metadata:lavfi.signalstats.YMAX})
                   U (%{metadata:lavfi.signalstats.UMIN}-%{metadata:lavfi.signalstats.UMAX})
                   V (%{metadata:lavfi.signalstats.VMIN}-%{metadata:lavfi.signalstats.VMAX})
                   saturation maximum: %{metadata:lavfi.signalstats.SATMAX}

   signature
       Calculates the MPEG-7 Video Signature. The filter can handle more than
       one input. In this case the matching between the inputs can be
       calculated additionally.  The filter always passes through the first
       input. The signature of each stream can be written into a file.

       It accepts the following options:

       detectmode
           Enable or disable the matching process.

           Available values are:

           off Disable the calculation of a matching (default).

           full
               Calculate the matching for the whole video and output whether
               the whole video matches or only parts.

           fast
               Calculate only until a matching is found or the video ends.
               Should be faster in some cases.

       nb_inputs
           Set the number of inputs. The option value must be a non negative
           integer.  Default value is 1.

       filename
           Set the path to which the output is written. If there is more than
           one input, the path must be a prototype, i.e. must contain %d or
           %0nd (where n is a positive integer), that will be replaced with
           the input number. If no filename is specified, no output will be
           written. This is the default.

       format
           Choose the output format.

           Available values are:

           binary
               Use the specified binary representation (default).

           xml Use the specified xml representation.

       th_d
           Set threshold to detect one word as similar. The option value must
           be an integer greater than zero. The default value is 9000.

       th_dc
           Set threshold to detect all words as similar. The option value must
           be an integer greater than zero. The default value is 60000.

       th_xh
           Set threshold to detect frames as similar. The option value must be
           an integer greater than zero. The default value is 116.

       th_di
           Set the minimum length of a sequence in frames to recognize it as
           matching sequence. The option value must be a non negative integer
           value.  The default value is 0.

       th_it
           Set the minimum relation, that matching frames to all frames must
           have.  The option value must be a double value between 0 and 1. The
           default value is 0.5.

       Examples

       o   To calculate the signature of an input video and store it in
           signature.bin:

                   ffmpeg -i input.mkv -vf signature=filename=signature.bin -map 0:v -f null -

       o   To detect whether two videos match and store the signatures in XML
           format in signature0.xml and signature1.xml:

                   ffmpeg -i input1.mkv -i input2.mkv -filter_complex "[0:v][1:v] signature=nb_inputs=2:detectmode=full:format=xml:filename=signature%d.xml" -map :v -f null -

   smartblur
       Blur the input video without impacting the outlines.

       It accepts the following options:

       luma_radius, lr
           Set the luma radius. The option value must be a float number in the
           range [0.1,5.0] that specifies the variance of the gaussian filter
           used to blur the image (slower if larger). Default value is 1.0.

       luma_strength, ls
           Set the luma strength. The option value must be a float number in
           the range [-1.0,1.0] that configures the blurring. A value included
           in [0.0,1.0] will blur the image whereas a value included in
           [-1.0,0.0] will sharpen the image. Default value is 1.0.

       luma_threshold, lt
           Set the luma threshold used as a coefficient to determine whether a
           pixel should be blurred or not. The option value must be an integer
           in the range [-30,30]. A value of 0 will filter all the image, a
           value included in [0,30] will filter flat areas and a value
           included in [-30,0] will filter edges. Default value is 0.

       chroma_radius, cr
           Set the chroma radius. The option value must be a float number in
           the range [0.1,5.0] that specifies the variance of the gaussian
           filter used to blur the image (slower if larger). Default value is
           luma_radius.

       chroma_strength, cs
           Set the chroma strength. The option value must be a float number in
           the range [-1.0,1.0] that configures the blurring. A value included
           in [0.0,1.0] will blur the image whereas a value included in
           [-1.0,0.0] will sharpen the image. Default value is luma_strength.

       chroma_threshold, ct
           Set the chroma threshold used as a coefficient to determine whether
           a pixel should be blurred or not. The option value must be an
           integer in the range [-30,30]. A value of 0 will filter all the
           image, a value included in [0,30] will filter flat areas and a
           value included in [-30,0] will filter edges. Default value is
           luma_threshold.

       If a chroma option is not explicitly set, the corresponding luma value
       is set.

   sobel
       Apply sobel operator to input video stream.

       The filter accepts the following option:

       planes
           Set which planes will be processed, unprocessed planes will be
           copied.  By default value 0xf, all planes will be processed.

       scale
           Set value which will be multiplied with filtered result.

       delta
           Set value which will be added to filtered result.

       Commands

       This filter supports the all above options as commands.

   spp
       Apply a simple postprocessing filter that compresses and decompresses
       the image at several (or - in the case of quality level 6 - all) shifts
       and average the results.

       The filter accepts the following options:

       quality
           Set quality. This option defines the number of levels for
           averaging. It accepts an integer in the range 0-6. If set to 0, the
           filter will have no effect. A value of 6 means the higher quality.
           For each increment of that value the speed drops by a factor of
           approximately 2.  Default value is 3.

       qp  Force a constant quantization parameter. If not set, the filter
           will use the QP from the video stream (if available).

       mode
           Set thresholding mode. Available modes are:

           hard
               Set hard thresholding (default).

           soft
               Set soft thresholding (better de-ringing effect, but likely
               blurrier).

       use_bframe_qp
           Enable the use of the QP from the B-Frames if set to 1. Using this
           option may cause flicker since the B-Frames have often larger QP.
           Default is 0 (not enabled).

       Commands

       This filter supports the following commands:

       quality, level
           Set quality level. The value "max" can be used to set the maximum
           level, currently 6.

   sr
       Scale the input by applying one of the super-resolution methods based
       on convolutional neural networks. Supported models:

       o   Super-Resolution Convolutional Neural Network model (SRCNN).  See
           <https://arxiv.org/abs/1501.00092>.

       o   Efficient Sub-Pixel Convolutional Neural Network model (ESPCN).
           See <https://arxiv.org/abs/1609.05158>.

       Training scripts as well as scripts for model file (.pb) saving can be
       found at <https://github.com/XueweiMeng/sr/tree/sr_dnn_native>.
       Original repository is at
       <https://github.com/HighVoltageRocknRoll/sr.git>.

       Native model files (.model) can be generated from TensorFlow model
       files (.pb) by using tools/python/convert.py

       The filter accepts the following options:

       dnn_backend
           Specify which DNN backend to use for model loading and execution.
           This option accepts the following values:

           native
               Native implementation of DNN loading and execution.

           tensorflow
               TensorFlow backend. To enable this backend you need to install
               the TensorFlow for C library (see
               <https://www.tensorflow.org/install/install_c>) and configure
               FFmpeg with "--enable-libtensorflow"

           Default value is native.

       model
           Set path to model file specifying network architecture and its
           parameters.  Note that different backends use different file
           formats. TensorFlow backend can load files for both formats, while
           native backend can load files for only its format.

       scale_factor
           Set scale factor for SRCNN model. Allowed values are 2, 3 and 4.
           Default value is 2. Scale factor is necessary for SRCNN model,
           because it accepts input upscaled using bicubic upscaling with
           proper scale factor.

       This feature can also be finished with dnn_processing filter.

   ssim
       Obtain the SSIM (Structural SImilarity Metric) between two input
       videos.

       This filter takes in input two input videos, the first input is
       considered the "main" source and is passed unchanged to the output. The
       second input is used as a "reference" video for computing the SSIM.

       Both video inputs must have the same resolution and pixel format for
       this filter to work correctly. Also it assumes that both inputs have
       the same number of frames, which are compared one by one.

       The filter stores the calculated SSIM of each frame.

       The description of the accepted parameters follows.

       stats_file, f
           If specified the filter will use the named file to save the SSIM of
           each individual frame. When filename equals "-" the data is sent to
           standard output.

       The file printed if stats_file is selected, contains a sequence of
       key/value pairs of the form key:value for each compared couple of
       frames.

       A description of each shown parameter follows:

       n   sequential number of the input frame, starting from 1

       Y, U, V, R, G, B
           SSIM of the compared frames for the component specified by the
           suffix.

       All SSIM of the compared frames for the whole frame.

       dB  Same as above but in dB representation.

       This filter also supports the framesync options.

       Examples

       o   For example:

                   movie=ref_movie.mpg, setpts=PTS-STARTPTS [main];
                   [main][ref] ssim="stats_file=stats.log" [out]

           On this example the input file being processed is compared with the
           reference file ref_movie.mpg. The SSIM of each individual frame is
           stored in stats.log.

       o   Another example with both psnr and ssim at same time:

                   ffmpeg -i main.mpg -i ref.mpg -lavfi  "ssim;[0:v][1:v]psnr" -f null -

       o   Another example with different containers:

                   ffmpeg -i main.mpg -i ref.mkv -lavfi  "[0:v]settb=AVTB,setpts=PTS-STARTPTS[main];[1:v]settb=AVTB,setpts=PTS-STARTPTS[ref];[main][ref]ssim" -f null -

   stereo3d
       Convert between different stereoscopic image formats.

       The filters accept the following options:

       in  Set stereoscopic image format of input.

           Available values for input image formats are:

           sbsl
               side by side parallel (left eye left, right eye right)

           sbsr
               side by side crosseye (right eye left, left eye right)

           sbs2l
               side by side parallel with half width resolution (left eye
               left, right eye right)

           sbs2r
               side by side crosseye with half width resolution (right eye
               left, left eye right)

           abl
           tbl above-below (left eye above, right eye below)

           abr
           tbr above-below (right eye above, left eye below)

           ab2l
           tb2l
               above-below with half height resolution (left eye above, right
               eye below)

           ab2r
           tb2r
               above-below with half height resolution (right eye above, left
               eye below)

           al  alternating frames (left eye first, right eye second)

           ar  alternating frames (right eye first, left eye second)

           irl interleaved rows (left eye has top row, right eye starts on
               next row)

           irr interleaved rows (right eye has top row, left eye starts on
               next row)

           icl interleaved columns, left eye first

           icr interleaved columns, right eye first

               Default value is sbsl.

       out Set stereoscopic image format of output.

           sbsl
               side by side parallel (left eye left, right eye right)

           sbsr
               side by side crosseye (right eye left, left eye right)

           sbs2l
               side by side parallel with half width resolution (left eye
               left, right eye right)

           sbs2r
               side by side crosseye with half width resolution (right eye
               left, left eye right)

           abl
           tbl above-below (left eye above, right eye below)

           abr
           tbr above-below (right eye above, left eye below)

           ab2l
           tb2l
               above-below with half height resolution (left eye above, right
               eye below)

           ab2r
           tb2r
               above-below with half height resolution (right eye above, left
               eye below)

           al  alternating frames (left eye first, right eye second)

           ar  alternating frames (right eye first, left eye second)

           irl interleaved rows (left eye has top row, right eye starts on
               next row)

           irr interleaved rows (right eye has top row, left eye starts on
               next row)

           arbg
               anaglyph red/blue gray (red filter on left eye, blue filter on
               right eye)

           argg
               anaglyph red/green gray (red filter on left eye, green filter
               on right eye)

           arcg
               anaglyph red/cyan gray (red filter on left eye, cyan filter on
               right eye)

           arch
               anaglyph red/cyan half colored (red filter on left eye, cyan
               filter on right eye)

           arcc
               anaglyph red/cyan color (red filter on left eye, cyan filter on
               right eye)

           arcd
               anaglyph red/cyan color optimized with the least squares
               projection of dubois (red filter on left eye, cyan filter on
               right eye)

           agmg
               anaglyph green/magenta gray (green filter on left eye, magenta
               filter on right eye)

           agmh
               anaglyph green/magenta half colored (green filter on left eye,
               magenta filter on right eye)

           agmc
               anaglyph green/magenta colored (green filter on left eye,
               magenta filter on right eye)

           agmd
               anaglyph green/magenta color optimized with the least squares
               projection of dubois (green filter on left eye, magenta filter
               on right eye)

           aybg
               anaglyph yellow/blue gray (yellow filter on left eye, blue
               filter on right eye)

           aybh
               anaglyph yellow/blue half colored (yellow filter on left eye,
               blue filter on right eye)

           aybc
               anaglyph yellow/blue colored (yellow filter on left eye, blue
               filter on right eye)

           aybd
               anaglyph yellow/blue color optimized with the least squares
               projection of dubois (yellow filter on left eye, blue filter on
               right eye)

           ml  mono output (left eye only)

           mr  mono output (right eye only)

           chl checkerboard, left eye first

           chr checkerboard, right eye first

           icl interleaved columns, left eye first

           icr interleaved columns, right eye first

           hdmi
               HDMI frame pack

           Default value is arcd.

       Examples

       o   Convert input video from side by side parallel to anaglyph
           yellow/blue dubois:

                   stereo3d=sbsl:aybd

       o   Convert input video from above below (left eye above, right eye
           below) to side by side crosseye.

                   stereo3d=abl:sbsr

   streamselect, astreamselect
       Select video or audio streams.

       The filter accepts the following options:

       inputs
           Set number of inputs. Default is 2.

       map Set input indexes to remap to outputs.

       Commands

       The "streamselect" and "astreamselect" filter supports the following
       commands:

       map Set input indexes to remap to outputs.

       Examples

       o   Select first 5 seconds 1st stream and rest of time 2nd stream:

                   sendcmd='5.0 streamselect map 1',streamselect=inputs=2:map=0

       o   Same as above, but for audio:

                   asendcmd='5.0 astreamselect map 1',astreamselect=inputs=2:map=0

   subtitles
       Draw subtitles on top of input video using the libass library.

       To enable compilation of this filter you need to configure FFmpeg with
       "--enable-libass". This filter also requires a build with libavcodec
       and libavformat to convert the passed subtitles file to ASS (Advanced
       Substation Alpha) subtitles format.

       The filter accepts the following options:

       filename, f
           Set the filename of the subtitle file to read. It must be
           specified.

       original_size
           Specify the size of the original video, the video for which the ASS
           file was composed. For the syntax of this option, check the "Video
           size" section in the ffmpeg-utils manual.  Due to a misdesign in
           ASS aspect ratio arithmetic, this is necessary to correctly scale
           the fonts if the aspect ratio has been changed.

       fontsdir
           Set a directory path containing fonts that can be used by the
           filter.  These fonts will be used in addition to whatever the font
           provider uses.

       alpha
           Process alpha channel, by default alpha channel is untouched.

       charenc
           Set subtitles input character encoding. "subtitles" filter only.
           Only useful if not UTF-8.

       stream_index, si
           Set subtitles stream index. "subtitles" filter only.

       force_style
           Override default style or script info parameters of the subtitles.
           It accepts a string containing ASS style format "KEY=VALUE" couples
           separated by ",".

       If the first key is not specified, it is assumed that the first value
       specifies the filename.

       For example, to render the file sub.srt on top of the input video, use
       the command:

               subtitles=sub.srt

       which is equivalent to:

               subtitles=filename=sub.srt

       To render the default subtitles stream from file video.mkv, use:

               subtitles=video.mkv

       To render the second subtitles stream from that file, use:

               subtitles=video.mkv:si=1

       To make the subtitles stream from sub.srt appear in 80% transparent
       blue "DejaVu Serif", use:

               subtitles=sub.srt:force_style='Fontname=DejaVu Serif,PrimaryColour=&HCCFF0000'

   super2xsai
       Scale the input by 2x and smooth using the Super2xSaI (Scale and
       Interpolate) pixel art scaling algorithm.

       Useful for enlarging pixel art images without reducing sharpness.

   swaprect
       Swap two rectangular objects in video.

       This filter accepts the following options:

       w   Set object width.

       h   Set object height.

       x1  Set 1st rect x coordinate.

       y1  Set 1st rect y coordinate.

       x2  Set 2nd rect x coordinate.

       y2  Set 2nd rect y coordinate.

           All expressions are evaluated once for each frame.

       The all options are expressions containing the following constants:

       w
       h   The input width and height.

       a   same as w / h

       sar input sample aspect ratio

       dar input display aspect ratio, it is the same as (w / h) * sar

       n   The number of the input frame, starting from 0.

       t   The timestamp expressed in seconds. It's NAN if the input timestamp
           is unknown.

       pos the position in the file of the input frame, NAN if unknown

       Commands

       This filter supports the all above options as commands.

   swapuv
       Swap U & V plane.

   tblend
       Blend successive video frames.

       See blend

   telecine
       Apply telecine process to the video.

       This filter accepts the following options:

       first_field
           top, t
               top field first

           bottom, b
               bottom field first The default value is "top".

       pattern
           A string of numbers representing the pulldown pattern you wish to
           apply.  The default value is 23.

               Some typical patterns:

               NTSC output (30i):
               27.5p: 32222
               24p: 23 (classic)
               24p: 2332 (preferred)
               20p: 33
               18p: 334
               16p: 3444

               PAL output (25i):
               27.5p: 12222
               24p: 222222222223 ("Euro pulldown")
               16.67p: 33
               16p: 33333334

   thistogram
       Compute and draw a color distribution histogram for the input video
       across time.

       Unlike histogram video filter which only shows histogram of single
       input frame at certain time, this filter shows also past histograms of
       number of frames defined by "width" option.

       The computed histogram is a representation of the color component
       distribution in an image.

       The filter accepts the following options:

       width, w
           Set width of single color component output. Default value is 0.
           Value of 0 means width will be picked from input video.  This also
           set number of passed histograms to keep.  Allowed range is [0,
           8192].

       display_mode, d
           Set display mode.  It accepts the following values:

           stack
               Per color component graphs are placed below each other.

           parade
               Per color component graphs are placed side by side.

           overlay
               Presents information identical to that in the "parade", except
               that the graphs representing color components are superimposed
               directly over one another.

           Default is "stack".

       levels_mode, m
           Set mode. Can be either "linear", or "logarithmic".  Default is
           "linear".

       components, c
           Set what color components to display.  Default is 7.

       bgopacity, b
           Set background opacity. Default is 0.9.

       envelope, e
           Show envelope. Default is disabled.

       ecolor, ec
           Set envelope color. Default is "gold".

       slide
           Set slide mode.

           Available values for slide is:

           frame
               Draw new frame when right border is reached.

           replace
               Replace old columns with new ones.

           scroll
               Scroll from right to left.

           rscroll
               Scroll from left to right.

           picture
               Draw single picture.

           Default is "replace".

   threshold
       Apply threshold effect to video stream.

       This filter needs four video streams to perform thresholding.  First
       stream is stream we are filtering.  Second stream is holding threshold
       values, third stream is holding min values, and last, fourth stream is
       holding max values.

       The filter accepts the following option:

       planes
           Set which planes will be processed, unprocessed planes will be
           copied.  By default value 0xf, all planes will be processed.

       For example if first stream pixel's component value is less then
       threshold value of pixel component from 2nd threshold stream, third
       stream value will picked, otherwise fourth stream pixel component value
       will be picked.

       Using color source filter one can perform various types of
       thresholding:

       Examples

       o   Binary threshold, using gray color as threshold:

                   ffmpeg -i 320x240.avi -f lavfi -i color=gray -f lavfi -i color=black -f lavfi -i color=white -lavfi threshold output.avi

       o   Inverted binary threshold, using gray color as threshold:

                   ffmpeg -i 320x240.avi -f lavfi -i color=gray -f lavfi -i color=white -f lavfi -i color=black -lavfi threshold output.avi

       o   Truncate binary threshold, using gray color as threshold:

                   ffmpeg -i 320x240.avi -f lavfi -i color=gray -i 320x240.avi -f lavfi -i color=gray -lavfi threshold output.avi

       o   Threshold to zero, using gray color as threshold:

                   ffmpeg -i 320x240.avi -f lavfi -i color=gray -f lavfi -i color=white -i 320x240.avi -lavfi threshold output.avi

       o   Inverted threshold to zero, using gray color as threshold:

                   ffmpeg -i 320x240.avi -f lavfi -i color=gray -i 320x240.avi -f lavfi -i color=white -lavfi threshold output.avi

   thumbnail
       Select the most representative frame in a given sequence of consecutive
       frames.

       The filter accepts the following options:

       n   Set the frames batch size to analyze; in a set of n frames, the
           filter will pick one of them, and then handle the next batch of n
           frames until the end. Default is 100.

       Since the filter keeps track of the whole frames sequence, a bigger n
       value will result in a higher memory usage, so a high value is not
       recommended.

       Examples

       o   Extract one picture each 50 frames:

                   thumbnail=50

       o   Complete example of a thumbnail creation with ffmpeg:

                   ffmpeg -i in.avi -vf thumbnail,scale=300:200 -frames:v 1 out.png

   tile
       Tile several successive frames together.

       The untile filter can do the reverse.

       The filter accepts the following options:

       layout
           Set the grid size (i.e. the number of lines and columns). For the
           syntax of this option, check the "Video size" section in the
           ffmpeg-utils manual.

       nb_frames
           Set the maximum number of frames to render in the given area. It
           must be less than or equal to wxh. The default value is 0, meaning
           all the area will be used.

       margin
           Set the outer border margin in pixels.

       padding
           Set the inner border thickness (i.e. the number of pixels between
           frames). For more advanced padding options (such as having
           different values for the edges), refer to the pad video filter.

       color
           Specify the color of the unused area. For the syntax of this
           option, check the "Color" section in the ffmpeg-utils manual.  The
           default value of color is "black".

       overlap
           Set the number of frames to overlap when tiling several successive
           frames together.  The value must be between 0 and nb_frames - 1.

       init_padding
           Set the number of frames to initially be empty before displaying
           first output frame.  This controls how soon will one get first
           output frame.  The value must be between 0 and nb_frames - 1.

       Examples

       o   Produce 8x8 PNG tiles of all keyframes (-skip_frame nokey) in a
           movie:

                   ffmpeg -skip_frame nokey -i file.avi -vf 'scale=128:72,tile=8x8' -an -vsync 0 keyframes%03d.png

           The -vsync 0 is necessary to prevent ffmpeg from duplicating each
           output frame to accommodate the originally detected frame rate.

       o   Display 5 pictures in an area of "32" frames, with 7 pixels
           between them, and 2 pixels of initial margin, using mixed flat and
           named options:

                   tile=32:nb_frames=5:padding=7:margin=2

   tinterlace
       Perform various types of temporal field interlacing.

       Frames are counted starting from 1, so the first input frame is
       considered odd.

       The filter accepts the following options:

       mode
           Specify the mode of the interlacing. This option can also be
           specified as a value alone. See below for a list of values for this
           option.

           Available values are:

           merge, 0
               Move odd frames into the upper field, even into the lower
               field, generating a double height frame at half frame rate.

                        ------> time
                       Input:
                       Frame 1         Frame 2         Frame 3         Frame 4

                       11111           22222           33333           44444
                       11111           22222           33333           44444
                       11111           22222           33333           44444
                       11111           22222           33333           44444

                       Output:
                       11111                           33333
                       22222                           44444
                       11111                           33333
                       22222                           44444
                       11111                           33333
                       22222                           44444
                       11111                           33333
                       22222                           44444

           drop_even, 1
               Only output odd frames, even frames are dropped, generating a
               frame with unchanged height at half frame rate.

                        ------> time
                       Input:
                       Frame 1         Frame 2         Frame 3         Frame 4

                       11111           22222           33333           44444
                       11111           22222           33333           44444
                       11111           22222           33333           44444
                       11111           22222           33333           44444

                       Output:
                       11111                           33333
                       11111                           33333
                       11111                           33333
                       11111                           33333

           drop_odd, 2
               Only output even frames, odd frames are dropped, generating a
               frame with unchanged height at half frame rate.

                        ------> time
                       Input:
                       Frame 1         Frame 2         Frame 3         Frame 4

                       11111           22222           33333           44444
                       11111           22222           33333           44444
                       11111           22222           33333           44444
                       11111           22222           33333           44444

                       Output:
                                       22222                           44444
                                       22222                           44444
                                       22222                           44444
                                       22222                           44444

           pad, 3
               Expand each frame to full height, but pad alternate lines with
               black, generating a frame with double height at the same input
               frame rate.

                        ------> time
                       Input:
                       Frame 1         Frame 2         Frame 3         Frame 4

                       11111           22222           33333           44444
                       11111           22222           33333           44444
                       11111           22222           33333           44444
                       11111           22222           33333           44444

                       Output:
                       11111           .....           33333           .....
                       .....           22222           .....           44444
                       11111           .....           33333           .....
                       .....           22222           .....           44444
                       11111           .....           33333           .....
                       .....           22222           .....           44444
                       11111           .....           33333           .....
                       .....           22222           .....           44444

           interleave_top, 4
               Interleave the upper field from odd frames with the lower field
               from even frames, generating a frame with unchanged height at
               half frame rate.

                        ------> time
                       Input:
                       Frame 1         Frame 2         Frame 3         Frame 4

                       11111<-         22222           33333<-         44444
                       11111           22222<-         33333           44444<-
                       11111<-         22222           33333<-         44444
                       11111           22222<-         33333           44444<-

                       Output:
                       11111                           33333
                       22222                           44444
                       11111                           33333
                       22222                           44444

           interleave_bottom, 5
               Interleave the lower field from odd frames with the upper field
               from even frames, generating a frame with unchanged height at
               half frame rate.

                        ------> time
                       Input:
                       Frame 1         Frame 2         Frame 3         Frame 4

                       11111           22222<-         33333           44444<-
                       11111<-         22222           33333<-         44444
                       11111           22222<-         33333           44444<-
                       11111<-         22222           33333<-         44444

                       Output:
                       22222                           44444
                       11111                           33333
                       22222                           44444
                       11111                           33333

           interlacex2, 6
               Double frame rate with unchanged height. Frames are inserted
               each containing the second temporal field from the previous
               input frame and the first temporal field from the next input
               frame. This mode relies on the top_field_first flag. Useful for
               interlaced video displays with no field synchronisation.

                        ------> time
                       Input:
                       Frame 1         Frame 2         Frame 3         Frame 4

                       11111           22222           33333           44444
                        11111           22222           33333           44444
                       11111           22222           33333           44444
                        11111           22222           33333           44444

                       Output:
                       11111   22222   22222   33333   33333   44444   44444
                        11111   11111   22222   22222   33333   33333   44444
                       11111   22222   22222   33333   33333   44444   44444
                        11111   11111   22222   22222   33333   33333   44444

           mergex2, 7
               Move odd frames into the upper field, even into the lower
               field, generating a double height frame at same frame rate.

                        ------> time
                       Input:
                       Frame 1         Frame 2         Frame 3         Frame 4

                       11111           22222           33333           44444
                       11111           22222           33333           44444
                       11111           22222           33333           44444
                       11111           22222           33333           44444

                       Output:
                       11111           33333           33333           55555
                       22222           22222           44444           44444
                       11111           33333           33333           55555
                       22222           22222           44444           44444
                       11111           33333           33333           55555
                       22222           22222           44444           44444
                       11111           33333           33333           55555
                       22222           22222           44444           44444

           Numeric values are deprecated but are accepted for backward
           compatibility reasons.

           Default mode is "merge".

       flags
           Specify flags influencing the filter process.

           Available value for flags is:

           low_pass_filter, vlpf
               Enable linear vertical low-pass filtering in the filter.
               Vertical low-pass filtering is required when creating an
               interlaced destination from a progressive source which contains
               high-frequency vertical detail. Filtering will reduce interlace
               'twitter' and Moire patterning.

           complex_filter, cvlpf
               Enable complex vertical low-pass filtering.  This will slightly
               less reduce interlace 'twitter' and Moire patterning but better
               retain detail and subjective sharpness impression.

           bypass_il
               Bypass already interlaced frames, only adjust the frame rate.

           Vertical low-pass filtering and bypassing already interlaced frames
           can only be enabled for mode interleave_top and interleave_bottom.

   tmedian
       Pick median pixels from several successive input video frames.

       The filter accepts the following options:

       radius
           Set radius of median filter.  Default is 1. Allowed range is from 1
           to 127.

       planes
           Set which planes to filter. Default value is 15, by which all
           planes are processed.

       percentile
           Set median percentile. Default value is 0.5.  Default value of 0.5
           will pick always median values, while 0 will pick minimum values,
           and 1 maximum values.

       Commands

       This filter supports all above options as commands, excluding option
       "radius".

   tmidequalizer
       Apply Temporal Midway Video Equalization effect.

       Midway Video Equalization adjusts a sequence of video frames to have
       the same histograms, while maintaining their dynamics as much as
       possible. It's useful for e.g. matching exposures from a video frames
       sequence.

       This filter accepts the following option:

       radius
           Set filtering radius. Default is 5. Allowed range is from 1 to 127.

       sigma
           Set filtering sigma. Default is 0.5. This controls strength of
           filtering.  Setting this option to 0 effectively does nothing.

       planes
           Set which planes to process. Default is 15, which is all available
           planes.

   tmix
       Mix successive video frames.

       A description of the accepted options follows.

       frames
           The number of successive frames to mix. If unspecified, it defaults
           to 3.

       weights
           Specify weight of each input video frame.  Each weight is separated
           by space. If number of weights is smaller than number of frames
           last specified weight will be used for all remaining unset weights.

       scale
           Specify scale, if it is set it will be multiplied with sum of each
           weight multiplied with pixel values to give final destination pixel
           value. By default scale is auto scaled to sum of weights.

       Examples

       o   Average 7 successive frames:

                   tmix=frames=7:weights="1 1 1 1 1 1 1"

       o   Apply simple temporal convolution:

                   tmix=frames=3:weights="-1 3 -1"

       o   Similar as above but only showing temporal differences:

                   tmix=frames=3:weights="-1 2 -1":scale=1

       Commands

       This filter supports the following commands:

       weights
       scale
           Syntax is same as option with same name.

   tonemap
       Tone map colors from different dynamic ranges.

       This filter expects data in single precision floating point, as it
       needs to operate on (and can output) out-of-range values. Another
       filter, such as zscale, is needed to convert the resulting frame to a
       usable format.

       The tonemapping algorithms implemented only work on linear light, so
       input data should be linearized beforehand (and possibly correctly
       tagged).

               ffmpeg -i INPUT -vf zscale=transfer=linear,tonemap=clip,zscale=transfer=bt709,format=yuv420p OUTPUT

       Options

       The filter accepts the following options.

       tonemap
           Set the tone map algorithm to use.

           Possible values are:

           none
               Do not apply any tone map, only desaturate overbright pixels.

           clip
               Hard-clip any out-of-range values. Use it for perfect color
               accuracy for in-range values, while distorting out-of-range
               values.

           linear
               Stretch the entire reference gamut to a linear multiple of the
               display.

           gamma
               Fit a logarithmic transfer between the tone curves.

           reinhard
               Preserve overall image brightness with a simple curve, using
               nonlinear contrast, which results in flattening details and
               degrading color accuracy.

           hable
               Preserve both dark and bright details better than reinhard, at
               the cost of slightly darkening everything. Use it when detail
               preservation is more important than color and brightness
               accuracy.

           mobius
               Smoothly map out-of-range values, while retaining contrast and
               colors for in-range material as much as possible. Use it when
               color accuracy is more important than detail preservation.

           Default is none.

       param
           Tune the tone mapping algorithm.

           This affects the following algorithms:

           none
               Ignored.

           linear
               Specifies the scale factor to use while stretching.  Default to
               1.0.

           gamma
               Specifies the exponent of the function.  Default to 1.8.

           clip
               Specify an extra linear coefficient to multiply into the signal
               before clipping.  Default to 1.0.

           reinhard
               Specify the local contrast coefficient at the display peak.
               Default to 0.5, which means that in-gamut values will be about
               half as bright as when clipping.

           hable
               Ignored.

           mobius
               Specify the transition point from linear to mobius transform.
               Every value below this point is guaranteed to be mapped 1:1.
               The higher the value, the more accurate the result will be, at
               the cost of losing bright details.  Default to 0.3, which due
               to the steep initial slope still preserves in-range colors
               fairly accurately.

       desat
           Apply desaturation for highlights that exceed this level of
           brightness. The higher the parameter, the more color information
           will be preserved. This setting helps prevent unnaturally blown-out
           colors for super-highlights, by (smoothly) turning into white
           instead. This makes images feel more natural, at the cost of
           reducing information about out-of-range colors.

           The default of 2.0 is somewhat conservative and will mostly just
           apply to skies or directly sunlit surfaces. A setting of 0.0
           disables this option.

           This option works only if the input frame has a supported color
           tag.

       peak
           Override signal/nominal/reference peak with this value. Useful when
           the embedded peak information in display metadata is not reliable
           or when tone mapping from a lower range to a higher range.

   tpad
       Temporarily pad video frames.

       The filter accepts the following options:

       start
           Specify number of delay frames before input video stream. Default
           is 0.

       stop
           Specify number of padding frames after input video stream.  Set to
           -1 to pad indefinitely. Default is 0.

       start_mode
           Set kind of frames added to beginning of stream.  Can be either add
           or clone.  With add frames of solid-color are added.  With clone
           frames are clones of first frame.  Default is add.

       stop_mode
           Set kind of frames added to end of stream.  Can be either add or
           clone.  With add frames of solid-color are added.  With clone
           frames are clones of last frame.  Default is add.

       start_duration, stop_duration
           Specify the duration of the start/stop delay. See the Time duration
           section in the ffmpeg-utils(1) manual for the accepted syntax.
           These options override start and stop. Default is 0.

       color
           Specify the color of the padded area. For the syntax of this
           option, check the "Color" section in the ffmpeg-utils manual.

           The default value of color is "black".

   transpose
       Transpose rows with columns in the input video and optionally flip it.

       It accepts the following parameters:

       dir Specify the transposition direction.

           Can assume the following values:

           0, 4, cclock_flip
               Rotate by 90 degrees counterclockwise and vertically flip
               (default), that is:

                       L.R     L.l
                       . . ->  . .
                       l.r     R.r

           1, 5, clock
               Rotate by 90 degrees clockwise, that is:

                       L.R     l.L
                       . . ->  . .
                       l.r     r.R

           2, 6, cclock
               Rotate by 90 degrees counterclockwise, that is:

                       L.R     R.r
                       . . ->  . .
                       l.r     L.l

           3, 7, clock_flip
               Rotate by 90 degrees clockwise and vertically flip, that is:

                       L.R     r.R
                       . . ->  . .
                       l.r     l.L

           For values between 4-7, the transposition is only done if the input
           video geometry is portrait and not landscape. These values are
           deprecated, the "passthrough" option should be used instead.

           Numerical values are deprecated, and should be dropped in favor of
           symbolic constants.

       passthrough
           Do not apply the transposition if the input geometry matches the
           one specified by the specified value. It accepts the following
           values:

           none
               Always apply transposition.

           portrait
               Preserve portrait geometry (when height >= width).

           landscape
               Preserve landscape geometry (when width >= height).

           Default value is "none".

       For example to rotate by 90 degrees clockwise and preserve portrait
       layout:

               transpose=dir=1:passthrough=portrait

       The command above can also be specified as:

               transpose=1:portrait

   transpose_npp
       Transpose rows with columns in the input video and optionally flip it.
       For more in depth examples see the transpose video filter, which shares
       mostly the same options.

       It accepts the following parameters:

       dir Specify the transposition direction.

           Can assume the following values:

           cclock_flip
               Rotate by 90 degrees counterclockwise and vertically flip.
               (default)

           clock
               Rotate by 90 degrees clockwise.

           cclock
               Rotate by 90 degrees counterclockwise.

           clock_flip
               Rotate by 90 degrees clockwise and vertically flip.

       passthrough
           Do not apply the transposition if the input geometry matches the
           one specified by the specified value. It accepts the following
           values:

           none
               Always apply transposition. (default)

           portrait
               Preserve portrait geometry (when height >= width).

           landscape
               Preserve landscape geometry (when width >= height).

   trim
       Trim the input so that the output contains one continuous subpart of
       the input.

       It accepts the following parameters:

       start
           Specify the time of the start of the kept section, i.e. the frame
           with the timestamp start will be the first frame in the output.

       end Specify the time of the first frame that will be dropped, i.e. the
           frame immediately preceding the one with the timestamp end will be
           the last frame in the output.

       start_pts
           This is the same as start, except this option sets the start
           timestamp in timebase units instead of seconds.

       end_pts
           This is the same as end, except this option sets the end timestamp
           in timebase units instead of seconds.

       duration
           The maximum duration of the output in seconds.

       start_frame
           The number of the first frame that should be passed to the output.

       end_frame
           The number of the first frame that should be dropped.

       start, end, and duration are expressed as time duration specifications;
       see the Time duration section in the ffmpeg-utils(1) manual for the
       accepted syntax.

       Note that the first two sets of the start/end options and the duration
       option look at the frame timestamp, while the _frame variants simply
       count the frames that pass through the filter. Also note that this
       filter does not modify the timestamps. If you wish for the output
       timestamps to start at zero, insert a setpts filter after the trim
       filter.

       If multiple start or end options are set, this filter tries to be
       greedy and keep all the frames that match at least one of the specified
       constraints. To keep only the part that matches all the constraints at
       once, chain multiple trim filters.

       The defaults are such that all the input is kept. So it is possible to
       set e.g.  just the end values to keep everything before the specified
       time.

       Examples:

       o   Drop everything except the second minute of input:

                   ffmpeg -i INPUT -vf trim=60:120

       o   Keep only the first second:

                   ffmpeg -i INPUT -vf trim=duration=1

   unpremultiply
       Apply alpha unpremultiply effect to input video stream using first
       plane of second stream as alpha.

       Both streams must have same dimensions and same pixel format.

       The filter accepts the following option:

       planes
           Set which planes will be processed, unprocessed planes will be
           copied.  By default value 0xf, all planes will be processed.

           If the format has 1 or 2 components, then luma is bit 0.  If the
           format has 3 or 4 components: for RGB formats bit 0 is green, bit 1
           is blue and bit 2 is red; for YUV formats bit 0 is luma, bit 1 is
           chroma-U and bit 2 is chroma-V.  If present, the alpha channel is
           always the last bit.

       inplace
           Do not require 2nd input for processing, instead use alpha plane
           from input stream.

   unsharp
       Sharpen or blur the input video.

       It accepts the following parameters:

       luma_msize_x, lx
           Set the luma matrix horizontal size. It must be an odd integer
           between 3 and 23. The default value is 5.

       luma_msize_y, ly
           Set the luma matrix vertical size. It must be an odd integer
           between 3 and 23. The default value is 5.

       luma_amount, la
           Set the luma effect strength. It must be a floating point number,
           reasonable values lay between -1.5 and 1.5.

           Negative values will blur the input video, while positive values
           will sharpen it, a value of zero will disable the effect.

           Default value is 1.0.

       chroma_msize_x, cx
           Set the chroma matrix horizontal size. It must be an odd integer
           between 3 and 23. The default value is 5.

       chroma_msize_y, cy
           Set the chroma matrix vertical size. It must be an odd integer
           between 3 and 23. The default value is 5.

       chroma_amount, ca
           Set the chroma effect strength. It must be a floating point number,
           reasonable values lay between -1.5 and 1.5.

           Negative values will blur the input video, while positive values
           will sharpen it, a value of zero will disable the effect.

           Default value is 0.0.

       All parameters are optional and default to the equivalent of the string
       '5:5:1.0:5:5:0.0'.

       Examples

       o   Apply strong luma sharpen effect:

                   unsharp=luma_msize_x=7:luma_msize_y=7:luma_amount=2.5

       o   Apply a strong blur of both luma and chroma parameters:

                   unsharp=7:7:-2:7:7:-2

   untile
       Decompose a video made of tiled images into the individual images.

       The frame rate of the output video is the frame rate of the input video
       multiplied by the number of tiles.

       This filter does the reverse of tile.

       The filter accepts the following options:

       layout
           Set the grid size (i.e. the number of lines and columns). For the
           syntax of this option, check the "Video size" section in the
           ffmpeg-utils manual.

       Examples

       o   Produce a 1-second video from a still image file made of 25 frames
           stacked vertically, like an analogic film reel:

                   ffmpeg -r 1 -i image.jpg -vf untile=1x25 movie.mkv

   uspp
       Apply ultra slow/simple postprocessing filter that compresses and
       decompresses the image at several (or - in the case of quality level 8
       - all) shifts and average the results.

       The way this differs from the behavior of spp is that uspp actually
       encodes & decodes each case with libavcodec Snow, whereas spp uses a
       simplified intra only 8x8 DCT similar to MJPEG.

       The filter accepts the following options:

       quality
           Set quality. This option defines the number of levels for
           averaging. It accepts an integer in the range 0-8. If set to 0, the
           filter will have no effect. A value of 8 means the higher quality.
           For each increment of that value the speed drops by a factor of
           approximately 2.  Default value is 3.

       qp  Force a constant quantization parameter. If not set, the filter
           will use the QP from the video stream (if available).

   v360
       Convert 360 videos between various formats.

       The filter accepts the following options:

       input
       output
           Set format of the input/output video.

           Available formats:

           e
           equirect
               Equirectangular projection.

           cx2
           c6x1
           c1x6
               Cubemap with 32/6x1/1x6 layout.

               Format specific options:

               in_pad
               out_pad
                   Set padding proportion for the input/output cubemap. Values
                   in decimals.

                   Example values:

                   0   No padding.

                   0.01
                       1% of face is padding. For example, with 1920x1280
                       resolution face size would be 640x640 and padding would
                       be 3 pixels from each side. (640 * 0.01 = 6 pixels)

                   Default value is @samp{0}.  Maximum value is @samp{0.1}.

               fin_pad
               fout_pad
                   Set fixed padding for the input/output cubemap. Values in
                   pixels.

                   Default value is @samp{0}. If greater than zero it
                   overrides other padding options.

               in_forder
               out_forder
                   Set order of faces for the input/output cubemap. Choose one
                   direction for each position.

                   Designation of directions:

                   r   right

                   l   left

                   u   up

                   d   down

                   f   forward

                   b   back

                   Default value is @samp{rludfb}.

               in_frot
               out_frot
                   Set rotation of faces for the input/output cubemap. Choose
                   one angle for each position.

                   Designation of angles:

                   0   0 degrees clockwise

                   1   90 degrees clockwise

                   2   180 degrees clockwise

                   3   270 degrees clockwise

                   Default value is @samp{000000}.

           eac Equi-Angular Cubemap.

           flat
           gnomonic
           rectilinear
               Regular video.

               Format specific options:

               h_fov
               v_fov
               d_fov
                   Set output horizontal/vertical/diagonal field of view.
                   Values in degrees.

                   If diagonal field of view is set it overrides horizontal
                   and vertical field of view.

               ih_fov
               iv_fov
               id_fov
                   Set input horizontal/vertical/diagonal field of view.
                   Values in degrees.

                   If diagonal field of view is set it overrides horizontal
                   and vertical field of view.

           dfisheye
               Dual fisheye.

               Format specific options:

               h_fov
               v_fov
               d_fov
                   Set output horizontal/vertical/diagonal field of view.
                   Values in degrees.

                   If diagonal field of view is set it overrides horizontal
                   and vertical field of view.

               ih_fov
               iv_fov
               id_fov
                   Set input horizontal/vertical/diagonal field of view.
                   Values in degrees.

                   If diagonal field of view is set it overrides horizontal
                   and vertical field of view.

           barrel
           fb
           barrelsplit
               Facebook's 360 formats.

           sg  Stereographic format.

               Format specific options:

               h_fov
               v_fov
               d_fov
                   Set output horizontal/vertical/diagonal field of view.
                   Values in degrees.

                   If diagonal field of view is set it overrides horizontal
                   and vertical field of view.

               ih_fov
               iv_fov
               id_fov
                   Set input horizontal/vertical/diagonal field of view.
                   Values in degrees.

                   If diagonal field of view is set it overrides horizontal
                   and vertical field of view.

           mercator
               Mercator format.

           ball
               Ball format, gives significant distortion toward the back.

           hammer
               Hammer-Aitoff map projection format.

           sinusoidal
               Sinusoidal map projection format.

           fisheye
               Fisheye projection.

               Format specific options:

               h_fov
               v_fov
               d_fov
                   Set output horizontal/vertical/diagonal field of view.
                   Values in degrees.

                   If diagonal field of view is set it overrides horizontal
                   and vertical field of view.

               ih_fov
               iv_fov
               id_fov
                   Set input horizontal/vertical/diagonal field of view.
                   Values in degrees.

                   If diagonal field of view is set it overrides horizontal
                   and vertical field of view.

           pannini
               Pannini projection.

               Format specific options:

               h_fov
                   Set output pannini parameter.

               ih_fov
                   Set input pannini parameter.

           cylindrical
               Cylindrical projection.

               Format specific options:

               h_fov
               v_fov
               d_fov
                   Set output horizontal/vertical/diagonal field of view.
                   Values in degrees.

                   If diagonal field of view is set it overrides horizontal
                   and vertical field of view.

               ih_fov
               iv_fov
               id_fov
                   Set input horizontal/vertical/diagonal field of view.
                   Values in degrees.

                   If diagonal field of view is set it overrides horizontal
                   and vertical field of view.

           perspective
               Perspective projection. (output only)

               Format specific options:

               v_fov
                   Set perspective parameter.

           tetrahedron
               Tetrahedron projection.

           tsp Truncated square pyramid projection.

           he
           hequirect
               Half equirectangular projection.

           equisolid
               Equisolid format.

               Format specific options:

               h_fov
               v_fov
               d_fov
                   Set output horizontal/vertical/diagonal field of view.
                   Values in degrees.

                   If diagonal field of view is set it overrides horizontal
                   and vertical field of view.

               ih_fov
               iv_fov
               id_fov
                   Set input horizontal/vertical/diagonal field of view.
                   Values in degrees.

                   If diagonal field of view is set it overrides horizontal
                   and vertical field of view.

           og  Orthographic format.

               Format specific options:

               h_fov
               v_fov
               d_fov
                   Set output horizontal/vertical/diagonal field of view.
                   Values in degrees.

                   If diagonal field of view is set it overrides horizontal
                   and vertical field of view.

               ih_fov
               iv_fov
               id_fov
                   Set input horizontal/vertical/diagonal field of view.
                   Values in degrees.

                   If diagonal field of view is set it overrides horizontal
                   and vertical field of view.

           octahedron
               Octahedron projection.

       interp
           Set interpolation method.Note: more complex interpolation methods
           require much more memory to run.

           Available methods:

           near
           nearest
               Nearest neighbour.

           line
           linear
               Bilinear interpolation.

           lagrange9
               Lagrange9 interpolation.

           cube
           cubic
               Bicubic interpolation.

           lanc
           lanczos
               Lanczos interpolation.

           sp16
           spline16
               Spline16 interpolation.

           gauss
           gaussian
               Gaussian interpolation.

           mitchell
               Mitchell interpolation.

           Default value is @samp{line}.

       w
       h   Set the output video resolution.

           Default resolution depends on formats.

       in_stereo
       out_stereo
           Set the input/output stereo format.

           2d  2D mono

           sbs Side by side

           tb  Top bottom

           Default value is @samp{2d} for input and output format.

       yaw
       pitch
       roll
           Set rotation for the output video. Values in degrees.

       rorder
           Set rotation order for the output video. Choose one item for each
           position.

           y, Y
               yaw

           p, P
               pitch

           r, R
               roll

           Default value is @samp{ypr}.

       h_flip
       v_flip
       d_flip
           Flip the output video horizontally(swaps
           left-right)/vertically(swaps up-down)/in-depth(swaps back-forward).
           Boolean values.

       ih_flip
       iv_flip
           Set if input video is flipped horizontally/vertically. Boolean
           values.

       in_trans
           Set if input video is transposed. Boolean value, by default
           disabled.

       out_trans
           Set if output video needs to be transposed. Boolean value, by
           default disabled.

       alpha_mask
           Build mask in alpha plane for all unmapped pixels by marking them
           fully transparent. Boolean value, by default disabled.

       Examples

       o   Convert equirectangular video to cubemap with 32 layout and 1%
           padding using bicubic interpolation:

                   ffmpeg -i input.mkv -vf v360=e:c32:cubic:out_pad=0.01 output.mkv

       o   Extract back view of Equi-Angular Cubemap:

                   ffmpeg -i input.mkv -vf v360=eac:flat:yaw=180 output.mkv

       o   Convert transposed and horizontally flipped Equi-Angular Cubemap in
           side-by-side stereo format to equirectangular top-bottom stereo
           format:

                   v360=eac:equirect:in_stereo=sbs:in_trans=1:ih_flip=1:out_stereo=tb

       Commands

       This filter supports subset of above options as commands.

   vaguedenoiser
       Apply a wavelet based denoiser.

       It transforms each frame from the video input into the wavelet domain,
       using Cohen-Daubechies-Feauveau 9/7. Then it applies some filtering to
       the obtained coefficients. It does an inverse wavelet transform after.
       Due to wavelet properties, it should give a nice smoothed result, and
       reduced noise, without blurring picture features.

       This filter accepts the following options:

       threshold
           The filtering strength. The higher, the more filtered the video
           will be.  Hard thresholding can use a higher threshold than soft
           thresholding before the video looks overfiltered. Default value is
           2.

       method
           The filtering method the filter will use.

           It accepts the following values:

           hard
               All values under the threshold will be zeroed.

           soft
               All values under the threshold will be zeroed. All values above
               will be reduced by the threshold.

           garrote
               Scales or nullifies coefficients - intermediary between (more)
               soft and (less) hard thresholding.

           Default is garrote.

       nsteps
           Number of times, the wavelet will decompose the picture. Picture
           can't be decomposed beyond a particular point (typically, 8 for a
           640x480 frame - as 2^9 = 512 > 480). Valid values are integers
           between 1 and 32. Default value is 6.

       percent
           Partial of full denoising (limited coefficients shrinking), from 0
           to 100. Default value is 85.

       planes
           A list of the planes to process. By default all planes are
           processed.

       type
           The threshold type the filter will use.

           It accepts the following values:

           universal
               Threshold used is same for all decompositions.

           bayes
               Threshold used depends also on each decomposition coefficients.

           Default is universal.

   vectorscope
       Display 2 color component values in the two dimensional graph (which is
       called a vectorscope).

       This filter accepts the following options:

       mode, m
           Set vectorscope mode.

           It accepts the following values:

           gray
           tint
               Gray values are displayed on graph, higher brightness means
               more pixels have same component color value on location in
               graph. This is the default mode.

           color
               Gray values are displayed on graph. Surrounding pixels values
               which are not present in video frame are drawn in gradient of 2
               color components which are set by option "x" and "y". The 3rd
               color component is static.

           color2
               Actual color components values present in video frame are
               displayed on graph.

           color3
               Similar as color2 but higher frequency of same values "x" and
               "y" on graph increases value of another color component, which
               is luminance by default values of "x" and "y".

           color4
               Actual colors present in video frame are displayed on graph. If
               two different colors map to same position on graph then color
               with higher value of component not present in graph is picked.

           color5
               Gray values are displayed on graph. Similar to "color" but with
               3rd color component picked from radial gradient.

       x   Set which color component will be represented on X-axis. Default is
           1.

       y   Set which color component will be represented on Y-axis. Default is
           2.

       intensity, i
           Set intensity, used by modes: gray, color, color3 and color5 for
           increasing brightness of color component which represents frequency
           of (X, Y) location in graph.

       envelope, e
           none
               No envelope, this is default.

           instant
               Instant envelope, even darkest single pixel will be clearly
               highlighted.

           peak
               Hold maximum and minimum values presented in graph over time.
               This way you can still spot out of range values without
               constantly looking at vectorscope.

           peak+instant
               Peak and instant envelope combined together.

       graticule, g
           Set what kind of graticule to draw.

           none
           green
           color
           invert
       opacity, o
           Set graticule opacity.

       flags, f
           Set graticule flags.

           white
               Draw graticule for white point.

           black
               Draw graticule for black point.

           name
               Draw color points short names.

       bgopacity, b
           Set background opacity.

       lthreshold, l
           Set low threshold for color component not represented on X or Y
           axis.  Values lower than this value will be ignored. Default is 0.
           Note this value is multiplied with actual max possible value one
           pixel component can have. So for 8-bit input and low threshold
           value of 0.1 actual threshold is 0.1 * 255 = 25.

       hthreshold, h
           Set high threshold for color component not represented on X or Y
           axis.  Values higher than this value will be ignored. Default is 1.
           Note this value is multiplied with actual max possible value one
           pixel component can have. So for 8-bit input and high threshold
           value of 0.9 actual threshold is 0.9 * 255 = 230.

       colorspace, c
           Set what kind of colorspace to use when drawing graticule.

           auto
           601
           709

           Default is auto.

       tint0, t0
       tint1, t1
           Set color tint for gray/tint vectorscope mode. By default both
           options are zero.  This means no tint, and output will remain gray.

   vidstabdetect
       Analyze video stabilization/deshaking. Perform pass 1 of 2, see
       vidstabtransform for pass 2.

       This filter generates a file with relative translation and rotation
       transform information about subsequent frames, which is then used by
       the vidstabtransform filter.

       To enable compilation of this filter you need to configure FFmpeg with
       "--enable-libvidstab".

       This filter accepts the following options:

       result
           Set the path to the file used to write the transforms information.
           Default value is transforms.trf.

       shakiness
           Set how shaky the video is and how quick the camera is. It accepts
           an integer in the range 1-10, a value of 1 means little shakiness,
           a value of 10 means strong shakiness. Default value is 5.

       accuracy
           Set the accuracy of the detection process. It must be a value in
           the range 1-15. A value of 1 means low accuracy, a value of 15
           means high accuracy. Default value is 15.

       stepsize
           Set stepsize of the search process. The region around minimum is
           scanned with 1 pixel resolution. Default value is 6.

       mincontrast
           Set minimum contrast. Below this value a local measurement field is
           discarded. Must be a floating point value in the range 0-1. Default
           value is 0.3.

       tripod
           Set reference frame number for tripod mode.

           If enabled, the motion of the frames is compared to a reference
           frame in the filtered stream, identified by the specified number.
           The idea is to compensate all movements in a more-or-less static
           scene and keep the camera view absolutely still.

           If set to 0, it is disabled. The frames are counted starting from
           1.

       show
           Show fields and transforms in the resulting frames. It accepts an
           integer in the range 0-2. Default value is 0, which disables any
           visualization.

       Examples

       o   Use default values:

                   vidstabdetect

       o   Analyze strongly shaky movie and put the results in file
           mytransforms.trf:

                   vidstabdetect=shakiness=10:accuracy=15:result="mytransforms.trf"

       o   Visualize the result of internal transformations in the resulting
           video:

                   vidstabdetect=show=1

       o   Analyze a video with medium shakiness using ffmpeg:

                   ffmpeg -i input -vf vidstabdetect=shakiness=5:show=1 dummy.avi

   vidstabtransform
       Video stabilization/deshaking: pass 2 of 2, see vidstabdetect for pass
       1.

       Read a file with transform information for each frame and
       apply/compensate them. Together with the vidstabdetect filter this can
       be used to deshake videos. See also
       <http://public.hronopik.de/vid.stab>. It is important to also use the
       unsharp filter, see below.

       To enable compilation of this filter you need to configure FFmpeg with
       "--enable-libvidstab".

       Options

       input
           Set path to the file used to read the transforms. Default value is
           transforms.trf.

       smoothing
           Set the number of frames (value*2 + 1) used for lowpass filtering
           the camera movements. Default value is 10.

           For example a number of 10 means that 21 frames are used (10 in the
           past and 10 in the future) to smoothen the motion in the video. A
           larger value leads to a smoother video, but limits the acceleration
           of the camera (pan/tilt movements). 0 is a special case where a
           static camera is simulated.

       optalgo
           Set the camera path optimization algorithm.

           Accepted values are:

           gauss
               gaussian kernel low-pass filter on camera motion (default)

           avg averaging on transformations

       maxshift
           Set maximal number of pixels to translate frames. Default value is
           -1, meaning no limit.

       maxangle
           Set maximal angle in radians (degree*PI/180) to rotate frames.
           Default value is -1, meaning no limit.

       crop
           Specify how to deal with borders that may be visible due to
           movement compensation.

           Available values are:

           keep
               keep image information from previous frame (default)

           black
               fill the border black

       invert
           Invert transforms if set to 1. Default value is 0.

       relative
           Consider transforms as relative to previous frame if set to 1,
           absolute if set to 0. Default value is 0.

       zoom
           Set percentage to zoom. A positive value will result in a zoom-in
           effect, a negative value in a zoom-out effect. Default value is 0
           (no zoom).

       optzoom
           Set optimal zooming to avoid borders.

           Accepted values are:

           0   disabled

           1   optimal static zoom value is determined (only very strong
               movements will lead to visible borders) (default)

           2   optimal adaptive zoom value is determined (no borders will be
               visible), see zoomspeed

           Note that the value given at zoom is added to the one calculated
           here.

       zoomspeed
           Set percent to zoom maximally each frame (enabled when optzoom is
           set to 2). Range is from 0 to 5, default value is 0.25.

       interpol
           Specify type of interpolation.

           Available values are:

           no  no interpolation

           linear
               linear only horizontal

           bilinear
               linear in both directions (default)

           bicubic
               cubic in both directions (slow)

       tripod
           Enable virtual tripod mode if set to 1, which is equivalent to
           "relative=0:smoothing=0". Default value is 0.

           Use also "tripod" option of vidstabdetect.

       debug
           Increase log verbosity if set to 1. Also the detected global
           motions are written to the temporary file global_motions.trf.
           Default value is 0.

       Examples

       o   Use ffmpeg for a typical stabilization with default values:

                   ffmpeg -i inp.mpeg -vf vidstabtransform,unsharp=5:5:0.8:3:3:0.4 inp_stabilized.mpeg

           Note the use of the unsharp filter which is always recommended.

       o   Zoom in a bit more and load transform data from a given file:

                   vidstabtransform=zoom=5:input="mytransforms.trf"

       o   Smoothen the video even more:

                   vidstabtransform=smoothing=30

   vflip
       Flip the input video vertically.

       For example, to vertically flip a video with ffmpeg:

               ffmpeg -i in.avi -vf "vflip" out.avi

   vfrdet
       Detect variable frame rate video.

       This filter tries to detect if the input is variable or constant frame
       rate.

       At end it will output number of frames detected as having variable
       delta pts, and ones with constant delta pts.  If there was frames with
       variable delta, than it will also show min, max and average delta
       encountered.

   vibrance
       Boost or alter saturation.

       The filter accepts the following options:

       intensity
           Set strength of boost if positive value or strength of alter if
           negative value.  Default is 0. Allowed range is from -2 to 2.

       rbal
           Set the red balance. Default is 1. Allowed range is from -10 to 10.

       gbal
           Set the green balance. Default is 1. Allowed range is from -10 to
           10.

       bbal
           Set the blue balance. Default is 1. Allowed range is from -10 to
           10.

       rlum
           Set the red luma coefficient.

       glum
           Set the green luma coefficient.

       blum
           Set the blue luma coefficient.

       alternate
           If "intensity" is negative and this is set to 1, colors will
           change, otherwise colors will be less saturated, more towards gray.

       Commands

       This filter supports the all above options as commands.

   vif
       Obtain the average VIF (Visual Information Fidelity) between two input
       videos.

       This filter takes two input videos.

       Both input videos must have the same resolution and pixel format for
       this filter to work correctly. Also it assumes that both inputs have
       the same number of frames, which are compared one by one.

       The obtained average VIF score is printed through the logging system.

       The filter stores the calculated VIF score of each frame.

       In the below example the input file main.mpg being processed is
       compared with the reference file ref.mpg.

               ffmpeg -i main.mpg -i ref.mpg -lavfi vif -f null -

   vignette
       Make or reverse a natural vignetting effect.

       The filter accepts the following options:

       angle, a
           Set lens angle expression as a number of radians.

           The value is clipped in the "[0,PI/2]" range.

           Default value: "PI/5"

       x0
       y0  Set center coordinates expressions. Respectively "w/2" and "h/2" by
           default.

       mode
           Set forward/backward mode.

           Available modes are:

           forward
               The larger the distance from the central point, the darker the
               image becomes.

           backward
               The larger the distance from the central point, the brighter
               the image becomes.  This can be used to reverse a vignette
               effect, though there is no automatic detection to extract the
               lens angle and other settings (yet). It can also be used to
               create a burning effect.

           Default value is forward.

       eval
           Set evaluation mode for the expressions (angle, x0, y0).

           It accepts the following values:

           init
               Evaluate expressions only once during the filter
               initialization.

           frame
               Evaluate expressions for each incoming frame. This is way
               slower than the init mode since it requires all the scalers to
               be re-computed, but it allows advanced dynamic expressions.

           Default value is init.

       dither
           Set dithering to reduce the circular banding effects. Default is 1
           (enabled).

       aspect
           Set vignette aspect. This setting allows one to adjust the shape of
           the vignette.  Setting this value to the SAR of the input will make
           a rectangular vignetting following the dimensions of the video.

           Default is "1/1".

       Expressions

       The alpha, x0 and y0 expressions can contain the following parameters.

       w
       h   input width and height

       n   the number of input frame, starting from 0

       pts the PTS (Presentation TimeStamp) time of the filtered video frame,
           expressed in TB units, NAN if undefined

       r   frame rate of the input video, NAN if the input frame rate is
           unknown

       t   the PTS (Presentation TimeStamp) of the filtered video frame,
           expressed in seconds, NAN if undefined

       tb  time base of the input video

       Examples

       o   Apply simple strong vignetting effect:

                   vignette=PI/4

       o   Make a flickering vignetting:

                   vignette='PI/4+random(1)*PI/50':eval=frame

   vmafmotion
       Obtain the average VMAF motion score of a video.  It is one of the
       component metrics of VMAF.

       The obtained average motion score is printed through the logging
       system.

       The filter accepts the following options:

       stats_file
           If specified, the filter will use the named file to save the motion
           score of each frame with respect to the previous frame.  When
           filename equals "-" the data is sent to standard output.

       Example:

               ffmpeg -i ref.mpg -vf vmafmotion -f null -

   vstack
       Stack input videos vertically.

       All streams must be of same pixel format and of same width.

       Note that this filter is faster than using overlay and pad filter to
       create same output.

       The filter accepts the following options:

       inputs
           Set number of input streams. Default is 2.

       shortest
           If set to 1, force the output to terminate when the shortest input
           terminates. Default value is 0.

   w3fdif
       Deinterlace the input video ("w3fdif" stands for "Weston 3 Field
       Deinterlacing Filter").

       Based on the process described by Martin Weston for BBC R&D, and
       implemented based on the de-interlace algorithm written by Jim
       Easterbrook for BBC R&D, the Weston 3 field deinterlacing filter uses
       filter coefficients calculated by BBC R&D.

       This filter uses field-dominance information in frame to decide which
       of each pair of fields to place first in the output.  If it gets it
       wrong use setfield filter before "w3fdif" filter.

       There are two sets of filter coefficients, so called "simple" and
       "complex". Which set of filter coefficients is used can be set by
       passing an optional parameter:

       filter
           Set the interlacing filter coefficients. Accepts one of the
           following values:

           simple
               Simple filter coefficient set.

           complex
               More-complex filter coefficient set.

           Default value is complex.

       mode
           The interlacing mode to adopt. It accepts one of the following
           values:

           frame
               Output one frame for each frame.

           field
               Output one frame for each field.

           The default value is "field".

       parity
           The picture field parity assumed for the input interlaced video. It
           accepts one of the following values:

           tff Assume the top field is first.

           bff Assume the bottom field is first.

           auto
               Enable automatic detection of field parity.

           The default value is "auto".  If the interlacing is unknown or the
           decoder does not export this information, top field first will be
           assumed.

       deint
           Specify which frames to deinterlace. Accepts one of the following
           values:

           all Deinterlace all frames,

           interlaced
               Only deinterlace frames marked as interlaced.

           Default value is all.

       Commands

       This filter supports same commands as options.

   waveform
       Video waveform monitor.

       The waveform monitor plots color component intensity. By default
       luminance only. Each column of the waveform corresponds to a column of
       pixels in the source video.

       It accepts the following options:

       mode, m
           Can be either "row", or "column". Default is "column".  In row
           mode, the graph on the left side represents color component value 0
           and the right side represents value = 255. In column mode, the top
           side represents color component value = 0 and bottom side
           represents value = 255.

       intensity, i
           Set intensity. Smaller values are useful to find out how many
           values of the same luminance are distributed across input
           rows/columns.  Default value is 0.04. Allowed range is [0, 1].

       mirror, r
           Set mirroring mode. 0 means unmirrored, 1 means mirrored.  In
           mirrored mode, higher values will be represented on the left side
           for "row" mode and at the top for "column" mode. Default is 1
           (mirrored).

       display, d
           Set display mode.  It accepts the following values:

           overlay
               Presents information identical to that in the "parade", except
               that the graphs representing color components are superimposed
               directly over one another.

               This display mode makes it easier to spot relative differences
               or similarities in overlapping areas of the color components
               that are supposed to be identical, such as neutral whites,
               grays, or blacks.

           stack
               Display separate graph for the color components side by side in
               "row" mode or one below the other in "column" mode.

           parade
               Display separate graph for the color components side by side in
               "column" mode or one below the other in "row" mode.

               Using this display mode makes it easy to spot color casts in
               the highlights and shadows of an image, by comparing the
               contours of the top and the bottom graphs of each waveform.
               Since whites, grays, and blacks are characterized by exactly
               equal amounts of red, green, and blue, neutral areas of the
               picture should display three waveforms of roughly equal
               width/height. If not, the correction is easy to perform by
               making level adjustments the three waveforms.

           Default is "stack".

       components, c
           Set which color components to display. Default is 1, which means
           only luminance or red color component if input is in RGB
           colorspace. If is set for example to 7 it will display all 3 (if)
           available color components.

       envelope, e
           none
               No envelope, this is default.

           instant
               Instant envelope, minimum and maximum values presented in graph
               will be easily visible even with small "step" value.

           peak
               Hold minimum and maximum values presented in graph across time.
               This way you can still spot out of range values without
               constantly looking at waveforms.

           peak+instant
               Peak and instant envelope combined together.

       filter, f
           lowpass
               No filtering, this is default.

           flat
               Luma and chroma combined together.

           aflat
               Similar as above, but shows difference between blue and red
               chroma.

           xflat
               Similar as above, but use different colors.

           yflat
               Similar as above, but again with different colors.

           chroma
               Displays only chroma.

           color
               Displays actual color value on waveform.

           acolor
               Similar as above, but with luma showing frequency of chroma
               values.

       graticule, g
           Set which graticule to display.

           none
               Do not display graticule.

           green
               Display green graticule showing legal broadcast ranges.

           orange
               Display orange graticule showing legal broadcast ranges.

           invert
               Display invert graticule showing legal broadcast ranges.

       opacity, o
           Set graticule opacity.

       flags, fl
           Set graticule flags.

           numbers
               Draw numbers above lines. By default enabled.

           dots
               Draw dots instead of lines.

       scale, s
           Set scale used for displaying graticule.

           digital
           millivolts
           ire

           Default is digital.

       bgopacity, b
           Set background opacity.

       tint0, t0
       tint1, t1
           Set tint for output.  Only used with lowpass filter and when
           display is not overlay and input pixel formats are not RGB.

   weave, doubleweave
       The "weave" takes a field-based video input and join each two
       sequential fields into single frame, producing a new double height clip
       with half the frame rate and half the frame count.

       The "doubleweave" works same as "weave" but without halving frame rate
       and frame count.

       It accepts the following option:

       first_field
           Set first field. Available values are:

           top, t
               Set the frame as top-field-first.

           bottom, b
               Set the frame as bottom-field-first.

       Examples

       o   Interlace video using select and separatefields filter:

                   separatefields,select=eq(mod(n,4),0)+eq(mod(n,4),3),weave

   xbr
       Apply the xBR high-quality magnification filter which is designed for
       pixel art. It follows a set of edge-detection rules, see
       <https://forums.libretro.com/t/xbr-algorithm-tutorial/123>.

       It accepts the following option:

       n   Set the scaling dimension: 2 for "2xBR", 3 for "3BR" and 4 for
           "4xBR".  Default is 3.

   xfade
       Apply cross fade from one input video stream to another input video
       stream.  The cross fade is applied for specified duration.

       The filter accepts the following options:

       transition
           Set one of available transition effects:

           custom
           fade
           wipeleft
           wiperight
           wipeup
           wipedown
           slideleft
           slideright
           slideup
           slidedown
           circlecrop
           rectcrop
           distance
           fadeblack
           fadewhite
           radial
           smoothleft
           smoothright
           smoothup
           smoothdown
           circleopen
           circleclose
           vertopen
           vertclose
           horzopen
           horzclose
           dissolve
           pixelize
           diagtl
           diagtr
           diagbl
           diagbr
           hlslice
           hrslice
           vuslice
           vdslice
           hblur
           fadegrays
           wipetl
           wipetr
           wipebl
           wipebr
           squeezeh
           squeezev

           Default transition effect is fade.

       duration
           Set cross fade duration in seconds.  Default duration is 1 second.

       offset
           Set cross fade start relative to first input stream in seconds.
           Default offset is 0.

       expr
           Set expression for custom transition effect.

           The expressions can use the following variables and functions:

           X
           Y   The coordinates of the current sample.

           W
           H   The width and height of the image.

           P   Progress of transition effect.

           PLANE
               Currently processed plane.

           A   Return value of first input at current location and plane.

           B   Return value of second input at current location and plane.

           a0(x, y)
           a1(x, y)
           a2(x, y)
           a3(x, y)
               Return the value of the pixel at location (x,y) of the
               first/second/third/fourth component of first input.

           b0(x, y)
           b1(x, y)
           b2(x, y)
           b3(x, y)
               Return the value of the pixel at location (x,y) of the
               first/second/third/fourth component of second input.

       Examples

       o   Cross fade from one input video to another input video, with fade
           transition and duration of transition of 2 seconds starting at
           offset of 5 seconds:

                   ffmpeg -i first.mp4 -i second.mp4 -filter_complex xfade=transition=fade:duration=2:offset=5 output.mp4

   xmedian
       Pick median pixels from several input videos.

       The filter accepts the following options:

       inputs
           Set number of inputs.  Default is 3. Allowed range is from 3 to
           255.  If number of inputs is even number, than result will be mean
           value between two median values.

       planes
           Set which planes to filter. Default value is 15, by which all
           planes are processed.

       percentile
           Set median percentile. Default value is 0.5.  Default value of 0.5
           will pick always median values, while 0 will pick minimum values,
           and 1 maximum values.

       Commands

       This filter supports all above options as commands, excluding option
       "inputs".

   xstack
       Stack video inputs into custom layout.

       All streams must be of same pixel format.

       The filter accepts the following options:

       inputs
           Set number of input streams. Default is 2.

       layout
           Specify layout of inputs.  This option requires the desired layout
           configuration to be explicitly set by the user.  This sets position
           of each video input in output. Each input is separated by '|'.  The
           first number represents the column, and the second number
           represents the row.  Numbers start at 0 and are separated by '_'.
           Optionally one can use wX and hX, where X is video input from which
           to take width or height.  Multiple values can be used when
           separated by '+'. In such case values are summed together.

           Note that if inputs are of different sizes gaps may appear, as not
           all of the output video frame will be filled. Similarly, videos can
           overlap each other if their position doesn't leave enough space for
           the full frame of adjoining videos.

           For 2 inputs, a default layout of "0_0|w0_0" is set. In all other
           cases, a layout must be set by the user.

       shortest
           If set to 1, force the output to terminate when the shortest input
           terminates. Default value is 0.

       fill
           If set to valid color, all unused pixels will be filled with that
           color.  By default fill is set to none, so it is disabled.

       Examples

       o   Display 4 inputs into 2x2 grid.

           Layout:

                   input1(0, 0)  | input3(w0, 0)
                   input2(0, h0) | input4(w0, h0)



                   xstack=inputs=4:layout=0_0|0_h0|w0_0|w0_h0

           Note that if inputs are of different sizes, gaps or overlaps may
           occur.

       o   Display 4 inputs into 1x4 grid.

           Layout:

                   input1(0, 0)
                   input2(0, h0)
                   input3(0, h0+h1)
                   input4(0, h0+h1+h2)



                   xstack=inputs=4:layout=0_0|0_h0|0_h0+h1|0_h0+h1+h2

           Note that if inputs are of different widths, unused space will
           appear.

       o   Display 9 inputs into 33 grid.

           Layout:

                   input1(0, 0)       | input4(w0, 0)      | input7(w0+w3, 0)
                   input2(0, h0)      | input5(w0, h0)     | input8(w0+w3, h0)
                   input3(0, h0+h1)   | input6(w0, h0+h1)  | input9(w0+w3, h0+h1)



                   xstack=inputs=9:layout=0_0|0_h0|0_h0+h1|w0_0|w0_h0|w0_h0+h1|w0+w3_0|w0+w3_h0|w0+w3_h0+h1

           Note that if inputs are of different sizes, gaps or overlaps may
           occur.

       o   Display 16 inputs into 4x4 grid.

           Layout:

                   input1(0, 0)       | input5(w0, 0)       | input9 (w0+w4, 0)       | input13(w0+w4+w8, 0)
                   input2(0, h0)      | input6(w0, h0)      | input10(w0+w4, h0)      | input14(w0+w4+w8, h0)
                   input3(0, h0+h1)   | input7(w0, h0+h1)   | input11(w0+w4, h0+h1)   | input15(w0+w4+w8, h0+h1)
                   input4(0, h0+h1+h2)| input8(w0, h0+h1+h2)| input12(w0+w4, h0+h1+h2)| input16(w0+w4+w8, h0+h1+h2)



                   xstack=inputs=16:layout=0_0|0_h0|0_h0+h1|0_h0+h1+h2|w0_0|w0_h0|w0_h0+h1|w0_h0+h1+h2|w0+w4_0|
                   w0+w4_h0|w0+w4_h0+h1|w0+w4_h0+h1+h2|w0+w4+w8_0|w0+w4+w8_h0|w0+w4+w8_h0+h1|w0+w4+w8_h0+h1+h2

           Note that if inputs are of different sizes, gaps or overlaps may
           occur.

   yadif
       Deinterlace the input video ("yadif" means "yet another deinterlacing
       filter").

       It accepts the following parameters:

       mode
           The interlacing mode to adopt. It accepts one of the following
           values:

           0, send_frame
               Output one frame for each frame.

           1, send_field
               Output one frame for each field.

           2, send_frame_nospatial
               Like "send_frame", but it skips the spatial interlacing check.

           3, send_field_nospatial
               Like "send_field", but it skips the spatial interlacing check.

           The default value is "send_frame".

       parity
           The picture field parity assumed for the input interlaced video. It
           accepts one of the following values:

           0, tff
               Assume the top field is first.

           1, bff
               Assume the bottom field is first.

           -1, auto
               Enable automatic detection of field parity.

           The default value is "auto".  If the interlacing is unknown or the
           decoder does not export this information, top field first will be
           assumed.

       deint
           Specify which frames to deinterlace. Accepts one of the following
           values:

           0, all
               Deinterlace all frames.

           1, interlaced
               Only deinterlace frames marked as interlaced.

           The default value is "all".

   yadif_cuda
       Deinterlace the input video using the yadif algorithm, but implemented
       in CUDA so that it can work as part of a GPU accelerated pipeline with
       nvdec and/or nvenc.

       It accepts the following parameters:

       mode
           The interlacing mode to adopt. It accepts one of the following
           values:

           0, send_frame
               Output one frame for each frame.

           1, send_field
               Output one frame for each field.

           2, send_frame_nospatial
               Like "send_frame", but it skips the spatial interlacing check.

           3, send_field_nospatial
               Like "send_field", but it skips the spatial interlacing check.

           The default value is "send_frame".

       parity
           The picture field parity assumed for the input interlaced video. It
           accepts one of the following values:

           0, tff
               Assume the top field is first.

           1, bff
               Assume the bottom field is first.

           -1, auto
               Enable automatic detection of field parity.

           The default value is "auto".  If the interlacing is unknown or the
           decoder does not export this information, top field first will be
           assumed.

       deint
           Specify which frames to deinterlace. Accepts one of the following
           values:

           0, all
               Deinterlace all frames.

           1, interlaced
               Only deinterlace frames marked as interlaced.

           The default value is "all".

   yaepblur
       Apply blur filter while preserving edges ("yaepblur" means "yet another
       edge preserving blur filter").  The algorithm is described in "J. S.
       Lee, Digital image enhancement and noise filtering by use of local
       statistics, IEEE Trans. Pattern Anal. Mach. Intell. PAMI-2, 1980."

       It accepts the following parameters:

       radius, r
           Set the window radius. Default value is 3.

       planes, p
           Set which planes to filter. Default is only the first plane.

       sigma, s
           Set blur strength. Default value is 128.

       Commands

       This filter supports same commands as options.

   zoompan
       Apply Zoom & Pan effect.

       This filter accepts the following options:

       zoom, z
           Set the zoom expression. Range is 1-10. Default is 1.

       x
       y   Set the x and y expression. Default is 0.

       d   Set the duration expression in number of frames.  This sets for how
           many number of frames effect will last for single input image.
           Default is 90.

       s   Set the output image size, default is 'hd720'.

       fps Set the output frame rate, default is '25'.

       Each expression can contain the following constants:

       in_w, iw
           Input width.

       in_h, ih
           Input height.

       out_w, ow
           Output width.

       out_h, oh
           Output height.

       in  Input frame count.

       on  Output frame count.

       in_time, it
           The input timestamp expressed in seconds. It's NAN if the input
           timestamp is unknown.

       out_time, time, ot
           The output timestamp expressed in seconds.

       x
       y   Last calculated 'x' and 'y' position from 'x' and 'y' expression
           for current input frame.

       px
       py  'x' and 'y' of last output frame of previous input frame or 0 when
           there was not yet such frame (first input frame).

       zoom
           Last calculated zoom from 'z' expression for current input frame.

       pzoom
           Last calculated zoom of last output frame of previous input frame.

       duration
           Number of output frames for current input frame. Calculated from
           'd' expression for each input frame.

       pduration
           number of output frames created for previous input frame

       a   Rational number: input width / input height

       sar sample aspect ratio

       dar display aspect ratio

       Examples

       o   Zoom in up to 1.5x and pan at same time to some spot near center of
           picture:

                   zoompan=z='min(zoom+0.0015,1.5)':d=700:x='if(gte(zoom,1.5),x,x+1/a)':y='if(gte(zoom,1.5),y,y+1)':s=640x360

       o   Zoom in up to 1.5x and pan always at center of picture:

                   zoompan=z='min(zoom+0.0015,1.5)':d=700:x='iw/2-(iw/zoom/2)':y='ih/2-(ih/zoom/2)'

       o   Same as above but without pausing:

                   zoompan=z='min(max(zoom,pzoom)+0.0015,1.5)':d=1:x='iw/2-(iw/zoom/2)':y='ih/2-(ih/zoom/2)'

       o   Zoom in 2x into center of picture only for the first second of the
           input video:

                   zoompan=z='if(between(in_time,0,1),2,1)':d=1:x='iw/2-(iw/zoom/2)':y='ih/2-(ih/zoom/2)'

   zscale
       Scale (resize) the input video, using the z.lib library:
       <https://github.com/sekrit-twc/zimg>. To enable compilation of this
       filter, you need to configure FFmpeg with "--enable-libzimg".

       The zscale filter forces the output display aspect ratio to be the same
       as the input, by changing the output sample aspect ratio.

       If the input image format is different from the format requested by the
       next filter, the zscale filter will convert the input to the requested
       format.

       Options

       The filter accepts the following options.

       width, w
       height, h
           Set the output video dimension expression. Default value is the
           input dimension.

           If the width or w value is 0, the input width is used for the
           output. If the height or h value is 0, the input height is used for
           the output.

           If one and only one of the values is -n with n >= 1, the zscale
           filter will use a value that maintains the aspect ratio of the
           input image, calculated from the other specified dimension. After
           that it will, however, make sure that the calculated dimension is
           divisible by n and adjust the value if necessary.

           If both values are -n with n >= 1, the behavior will be identical
           to both values being set to 0 as previously detailed.

           See below for the list of accepted constants for use in the
           dimension expression.

       size, s
           Set the video size. For the syntax of this option, check the "Video
           size" section in the ffmpeg-utils manual.

       dither, d
           Set the dither type.

           Possible values are:

           none
           ordered
           random
           error_diffusion

           Default is none.

       filter, f
           Set the resize filter type.

           Possible values are:

           point
           bilinear
           bicubic
           spline16
           spline36
           lanczos

           Default is bilinear.

       range, r
           Set the color range.

           Possible values are:

           input
           limited
           full

           Default is same as input.

       primaries, p
           Set the color primaries.

           Possible values are:

           input
           709
           unspecified
           170m
           240m
           2020

           Default is same as input.

       transfer, t
           Set the transfer characteristics.

           Possible values are:

           input
           709
           unspecified
           601
           linear
           2020_10
           2020_12
           smpte2084
           iec61966-2-1
           arib-std-b67

           Default is same as input.

       matrix, m
           Set the colorspace matrix.

           Possible value are:

           input
           709
           unspecified
           470bg
           170m
           2020_ncl
           2020_cl

           Default is same as input.

       rangein, rin
           Set the input color range.

           Possible values are:

           input
           limited
           full

           Default is same as input.

       primariesin, pin
           Set the input color primaries.

           Possible values are:

           input
           709
           unspecified
           170m
           240m
           2020

           Default is same as input.

       transferin, tin
           Set the input transfer characteristics.

           Possible values are:

           input
           709
           unspecified
           601
           linear
           2020_10
           2020_12

           Default is same as input.

       matrixin, min
           Set the input colorspace matrix.

           Possible value are:

           input
           709
           unspecified
           470bg
           170m
           2020_ncl
           2020_cl
       chromal, c
           Set the output chroma location.

           Possible values are:

           input
           left
           center
           topleft
           top
           bottomleft
           bottom
       chromalin, cin
           Set the input chroma location.

           Possible values are:

           input
           left
           center
           topleft
           top
           bottomleft
           bottom
       npl Set the nominal peak luminance.

       param_a
           Parameter A for scaling filters. Parameter "b" for bicubic, and the
           number of filter taps for lanczos.

       param_b
           Parameter B for scaling filters. Parameter "c" for bicubic.

       The values of the w and h options are expressions containing the
       following constants:

       in_w
       in_h
           The input width and height

       iw
       ih  These are the same as in_w and in_h.

       out_w
       out_h
           The output (scaled) width and height

       ow
       oh  These are the same as out_w and out_h

       a   The same as iw / ih

       sar input sample aspect ratio

       dar The input display aspect ratio. Calculated from "(iw / ih) * sar".

       hsub
       vsub
           horizontal and vertical input chroma subsample values. For example
           for the pixel format "yuv422p" hsub is 2 and vsub is 1.

       ohsub
       ovsub
           horizontal and vertical output chroma subsample values. For example
           for the pixel format "yuv422p" hsub is 2 and vsub is 1.

       Commands

       This filter supports the following commands:

       width, w
       height, h
           Set the output video dimension expression.  The command accepts the
           same syntax of the corresponding option.

           If the specified expression is not valid, it is kept at its current
           value.


OPENCL VIDEO FILTERS

       Below is a description of the currently available OpenCL video filters.

       To enable compilation of these filters you need to configure FFmpeg
       with "--enable-opencl".

       Running OpenCL filters requires you to initialize a hardware device and
       to pass that device to all filters in any filter graph.

       -init_hw_device opencl[=name][:device[,key=value...]]
           Initialise a new hardware device of type opencl called name, using
           the given device parameters.

       -filter_hw_device name
           Pass the hardware device called name to all filters in any filter
           graph.

       For more detailed information see
       <https://www.ffmpeg.org/ffmpeg.html#Advanced-Video-options>

       o   Example of choosing the first device on the second platform and
           running avgblur_opencl filter with default parameters on it.

                   -init_hw_device opencl=gpu:1.0 -filter_hw_device gpu -i INPUT -vf "hwupload, avgblur_opencl, hwdownload" OUTPUT

       Since OpenCL filters are not able to access frame data in normal
       memory, all frame data needs to be uploaded(hwupload) to hardware
       surfaces connected to the appropriate device before being used and then
       downloaded(hwdownload) back to normal memory. Note that hwupload will
       upload to a surface with the same layout as the software frame, so it
       may be necessary to add a format filter immediately before to get the
       input into the right format and hwdownload does not support all formats
       on the output - it may be necessary to insert an additional format
       filter immediately following in the graph to get the output in a
       supported format.

   avgblur_opencl
       Apply average blur filter.

       The filter accepts the following options:

       sizeX
           Set horizontal radius size.  Range is "[1, 1024]" and default value
           is 1.

       planes
           Set which planes to filter. Default value is 0xf, by which all
           planes are processed.

       sizeY
           Set vertical radius size. Range is "[1, 1024]" and default value is
           0. If zero, "sizeX" value will be used.

       Example

       o   Apply average blur filter with horizontal and vertical size of 3,
           setting each pixel of the output to the average value of the 7x7
           region centered on it in the input. For pixels on the edges of the
           image, the region does not extend beyond the image boundaries, and
           so out-of-range coordinates are not used in the calculations.

                   -i INPUT -vf "hwupload, avgblur_opencl=3, hwdownload" OUTPUT

   boxblur_opencl
       Apply a boxblur algorithm to the input video.

       It accepts the following parameters:

       luma_radius, lr
       luma_power, lp
       chroma_radius, cr
       chroma_power, cp
       alpha_radius, ar
       alpha_power, ap

       A description of the accepted options follows.

       luma_radius, lr
       chroma_radius, cr
       alpha_radius, ar
           Set an expression for the box radius in pixels used for blurring
           the corresponding input plane.

           The radius value must be a non-negative number, and must not be
           greater than the value of the expression "min(w,h)/2" for the luma
           and alpha planes, and of "min(cw,ch)/2" for the chroma planes.

           Default value for luma_radius is "2". If not specified,
           chroma_radius and alpha_radius default to the corresponding value
           set for luma_radius.

           The expressions can contain the following constants:

           w
           h   The input width and height in pixels.

           cw
           ch  The input chroma image width and height in pixels.

           hsub
           vsub
               The horizontal and vertical chroma subsample values. For
               example, for the pixel format "yuv422p", hsub is 2 and vsub is
               1.

       luma_power, lp
       chroma_power, cp
       alpha_power, ap
           Specify how many times the boxblur filter is applied to the
           corresponding plane.

           Default value for luma_power is 2. If not specified, chroma_power
           and alpha_power default to the corresponding value set for
           luma_power.

           A value of 0 will disable the effect.

       Examples

       Apply boxblur filter, setting each pixel of the output to the average
       value of box-radiuses luma_radius, chroma_radius, alpha_radius for each
       plane respectively. The filter will apply luma_power, chroma_power,
       alpha_power times onto the corresponding plane. For pixels on the edges
       of the image, the radius does not extend beyond the image boundaries,
       and so out-of-range coordinates are not used in the calculations.

       o   Apply a boxblur filter with the luma, chroma, and alpha radius set
           to 2 and luma, chroma, and alpha power set to 3. The filter will
           run 3 times with box-radius set to 2 for every plane of the image.

                   -i INPUT -vf "hwupload, boxblur_opencl=luma_radius=2:luma_power=3, hwdownload" OUTPUT
                   -i INPUT -vf "hwupload, boxblur_opencl=2:3, hwdownload" OUTPUT

       o   Apply a boxblur filter with luma radius set to 2, luma_power to 1,
           chroma_radius to 4, chroma_power to 5, alpha_radius to 3 and
           alpha_power to 7.

           For the luma plane, a 2x2 box radius will be run once.

           For the chroma plane, a 4x4 box radius will be run 5 times.

           For the alpha plane, a 33 box radius will be run 7 times.

                   -i INPUT -vf "hwupload, boxblur_opencl=2:1:4:5:3:7, hwdownload" OUTPUT

   colorkey_opencl
       RGB colorspace color keying.

       The filter accepts the following options:

       color
           The color which will be replaced with transparency.

       similarity
           Similarity percentage with the key color.

           0.01 matches only the exact key color, while 1.0 matches
           everything.

       blend
           Blend percentage.

           0.0 makes pixels either fully transparent, or not transparent at
           all.

           Higher values result in semi-transparent pixels, with a higher
           transparency the more similar the pixels color is to the key color.

       Examples

       o   Make every semi-green pixel in the input transparent with some
           slight blending:

                   -i INPUT -vf "hwupload, colorkey_opencl=green:0.3:0.1, hwdownload" OUTPUT

   convolution_opencl
       Apply convolution of 33, 5x5, 7x7 matrix.

       The filter accepts the following options:

       0m
       1m
       2m
       3m  Set matrix for each plane.  Matrix is sequence of 9, 25 or 49
           signed numbers.  Default value for each plane is "0 0 0 0 1 0 0 0
           0".

       0rdiv
       1rdiv
       2rdiv
       3rdiv
           Set multiplier for calculated value for each plane.  If unset or 0,
           it will be sum of all matrix elements.  The option value must be a
           float number greater or equal to 0.0. Default value is 1.0.

       0bias
       1bias
       2bias
       3bias
           Set bias for each plane. This value is added to the result of the
           multiplication.  Useful for making the overall image brighter or
           darker.  The option value must be a float number greater or equal
           to 0.0. Default value is 0.0.

       Examples

       o   Apply sharpen:

                   -i INPUT -vf "hwupload, convolution_opencl=0 -1 0 -1 5 -1 0 -1 0:0 -1 0 -1 5 -1 0 -1 0:0 -1 0 -1 5 -1 0 -1 0:0 -1 0 -1 5 -1 0 -1 0, hwdownload" OUTPUT

       o   Apply blur:

                   -i INPUT -vf "hwupload, convolution_opencl=1 1 1 1 1 1 1 1 1:1 1 1 1 1 1 1 1 1:1 1 1 1 1 1 1 1 1:1 1 1 1 1 1 1 1 1:1/9:1/9:1/9:1/9, hwdownload" OUTPUT

       o   Apply edge enhance:

                   -i INPUT -vf "hwupload, convolution_opencl=0 0 0 -1 1 0 0 0 0:0 0 0 -1 1 0 0 0 0:0 0 0 -1 1 0 0 0 0:0 0 0 -1 1 0 0 0 0:5:1:1:1:0:128:128:128, hwdownload" OUTPUT

       o   Apply edge detect:

                   -i INPUT -vf "hwupload, convolution_opencl=0 1 0 1 -4 1 0 1 0:0 1 0 1 -4 1 0 1 0:0 1 0 1 -4 1 0 1 0:0 1 0 1 -4 1 0 1 0:5:5:5:1:0:128:128:128, hwdownload" OUTPUT

       o   Apply laplacian edge detector which includes diagonals:

                   -i INPUT -vf "hwupload, convolution_opencl=1 1 1 1 -8 1 1 1 1:1 1 1 1 -8 1 1 1 1:1 1 1 1 -8 1 1 1 1:1 1 1 1 -8 1 1 1 1:5:5:5:1:0:128:128:0, hwdownload" OUTPUT

       o   Apply emboss:

                   -i INPUT -vf "hwupload, convolution_opencl=-2 -1 0 -1 1 1 0 1 2:-2 -1 0 -1 1 1 0 1 2:-2 -1 0 -1 1 1 0 1 2:-2 -1 0 -1 1 1 0 1 2, hwdownload" OUTPUT

   erosion_opencl
       Apply erosion effect to the video.

       This filter replaces the pixel by the local(33) minimum.

       It accepts the following options:

       threshold0
       threshold1
       threshold2
       threshold3
           Limit the maximum change for each plane. Range is "[0, 65535]" and
           default value is 65535.  If 0, plane will remain unchanged.

       coordinates
           Flag which specifies the pixel to refer to.  Range is "[0, 255]"
           and default value is 255, i.e. all eight pixels are used.

           Flags to local 33 coordinates region centered on "x":

               1 2 3

               4 x 5

               6 7 8

       Example

       o   Apply erosion filter with threshold0 set to 30, threshold1 set 40,
           threshold2 set to 50 and coordinates set to 231, setting each pixel
           of the output to the local minimum between pixels: 1, 2, 3, 6, 7, 8
           of the 33 region centered on it in the input. If the difference
           between input pixel and local minimum is more then threshold of the
           corresponding plane, output pixel will be set to input pixel -
           threshold of corresponding plane.

                   -i INPUT -vf "hwupload, erosion_opencl=30:40:50:coordinates=231, hwdownload" OUTPUT

   deshake_opencl
       Feature-point based video stabilization filter.

       The filter accepts the following options:

       tripod
           Simulates a tripod by preventing any camera movement whatsoever
           from the original frame. Defaults to 0.

       debug
           Whether or not additional debug info should be displayed, both in
           the processed output and in the console.

           Note that in order to see console debug output you will also need
           to pass "-v verbose" to ffmpeg.

           Viewing point matches in the output video is only supported for RGB
           input.

           Defaults to 0.

       adaptive_crop
           Whether or not to do a tiny bit of cropping at the borders to cut
           down on the amount of mirrored pixels.

           Defaults to 1.

       refine_features
           Whether or not feature points should be refined at a sub-pixel
           level.

           This can be turned off for a slight performance gain at the cost of
           precision.

           Defaults to 1.

       smooth_strength
           The strength of the smoothing applied to the camera path from 0.0
           to 1.0.

           1.0 is the maximum smoothing strength while values less than that
           result in less smoothing.

           0.0 causes the filter to adaptively choose a smoothing strength on
           a per-frame basis.

           Defaults to 0.0.

       smooth_window_multiplier
           Controls the size of the smoothing window (the number of frames
           buffered to determine motion information from).

           The size of the smoothing window is determined by multiplying the
           framerate of the video by this number.

           Acceptable values range from 0.1 to 10.0.

           Larger values increase the amount of motion data available for
           determining how to smooth the camera path, potentially improving
           smoothness, but also increase latency and memory usage.

           Defaults to 2.0.

       Examples

       o   Stabilize a video with a fixed, medium smoothing strength:

                   -i INPUT -vf "hwupload, deshake_opencl=smooth_strength=0.5, hwdownload" OUTPUT

       o   Stabilize a video with debugging (both in console and in rendered
           video):

                   -i INPUT -filter_complex "[0:v]format=rgba, hwupload, deshake_opencl=debug=1, hwdownload, format=rgba, format=yuv420p" -v verbose OUTPUT

   dilation_opencl
       Apply dilation effect to the video.

       This filter replaces the pixel by the local(33) maximum.

       It accepts the following options:

       threshold0
       threshold1
       threshold2
       threshold3
           Limit the maximum change for each plane. Range is "[0, 65535]" and
           default value is 65535.  If 0, plane will remain unchanged.

       coordinates
           Flag which specifies the pixel to refer to.  Range is "[0, 255]"
           and default value is 255, i.e. all eight pixels are used.

           Flags to local 33 coordinates region centered on "x":

               1 2 3

               4 x 5

               6 7 8

       Example

       o   Apply dilation filter with threshold0 set to 30, threshold1 set 40,
           threshold2 set to 50 and coordinates set to 231, setting each pixel
           of the output to the local maximum between pixels: 1, 2, 3, 6, 7, 8
           of the 33 region centered on it in the input. If the difference
           between input pixel and local maximum is more then threshold of the
           corresponding plane, output pixel will be set to input pixel +
           threshold of corresponding plane.

                   -i INPUT -vf "hwupload, dilation_opencl=30:40:50:coordinates=231, hwdownload" OUTPUT

   nlmeans_opencl
       Non-local Means denoise filter through OpenCL, this filter accepts same
       options as nlmeans.

   overlay_opencl
       Overlay one video on top of another.

       It takes two inputs and has one output. The first input is the "main"
       video on which the second input is overlaid.  This filter requires same
       memory layout for all the inputs. So, format conversion may be needed.

       The filter accepts the following options:

       x   Set the x coordinate of the overlaid video on the main video.
           Default value is 0.

       y   Set the y coordinate of the overlaid video on the main video.
           Default value is 0.

       Examples

       o   Overlay an image LOGO at the top-left corner of the INPUT video.
           Both inputs are yuv420p format.

                   -i INPUT -i LOGO -filter_complex "[0:v]hwupload[a], [1:v]format=yuv420p, hwupload[b], [a][b]overlay_opencl, hwdownload" OUTPUT

       o   The inputs have same memory layout for color channels , the overlay
           has additional alpha plane, like INPUT is yuv420p, and the LOGO is
           yuva420p.

                   -i INPUT -i LOGO -filter_complex "[0:v]hwupload[a], [1:v]format=yuva420p, hwupload[b], [a][b]overlay_opencl, hwdownload" OUTPUT

   pad_opencl
       Add paddings to the input image, and place the original input at the
       provided x, y coordinates.

       It accepts the following options:

       width, w
       height, h
           Specify an expression for the size of the output image with the
           paddings added. If the value for width or height is 0, the
           corresponding input size is used for the output.

           The width expression can reference the value set by the height
           expression, and vice versa.

           The default value of width and height is 0.

       x
       y   Specify the offsets to place the input image at within the padded
           area, with respect to the top/left border of the output image.

           The x expression can reference the value set by the y expression,
           and vice versa.

           The default value of x and y is 0.

           If x or y evaluate to a negative number, they'll be changed so the
           input image is centered on the padded area.

       color
           Specify the color of the padded area. For the syntax of this
           option, check the "Color" section in the ffmpeg-utils manual.

       aspect
           Pad to an aspect instead to a resolution.

       The value for the width, height, x, and y options are expressions
       containing the following constants:

       in_w
       in_h
           The input video width and height.

       iw
       ih  These are the same as in_w and in_h.

       out_w
       out_h
           The output width and height (the size of the padded area), as
           specified by the width and height expressions.

       ow
       oh  These are the same as out_w and out_h.

       x
       y   The x and y offsets as specified by the x and y expressions, or NAN
           if not yet specified.

       a   same as iw / ih

       sar input sample aspect ratio

       dar input display aspect ratio, it is the same as (iw / ih) * sar

   prewitt_opencl
       Apply the Prewitt operator
       (<https://en.wikipedia.org/wiki/Prewitt_operator>) to input video
       stream.

       The filter accepts the following option:

       planes
           Set which planes to filter. Default value is 0xf, by which all
           planes are processed.

       scale
           Set value which will be multiplied with filtered result.  Range is
           "[0.0, 65535]" and default value is 1.0.

       delta
           Set value which will be added to filtered result.  Range is
           "[-65535, 65535]" and default value is 0.0.

       Example

       o   Apply the Prewitt operator with scale set to 2 and delta set to 10.

                   -i INPUT -vf "hwupload, prewitt_opencl=scale=2:delta=10, hwdownload" OUTPUT

   program_opencl
       Filter video using an OpenCL program.

       source
           OpenCL program source file.

       kernel
           Kernel name in program.

       inputs
           Number of inputs to the filter.  Defaults to 1.

       size, s
           Size of output frames.  Defaults to the same as the first input.

       The "program_opencl" filter also supports the framesync options.

       The program source file must contain a kernel function with the given
       name, which will be run once for each plane of the output.  Each run on
       a plane gets enqueued as a separate 2D global NDRange with one work-
       item for each pixel to be generated.  The global ID offset for each
       work-item is therefore the coordinates of a pixel in the destination
       image.

       The kernel function needs to take the following arguments:

       o   Destination image, __write_only image2d_t.

           This image will become the output; the kernel should write all of
           it.

       o   Frame index, unsigned int.

           This is a counter starting from zero and increasing by one for each
           frame.

       o   Source images, __read_only image2d_t.

           These are the most recent images on each input.  The kernel may
           read from them to generate the output, but they can't be written
           to.

       Example programs:

       o   Copy the input to the output (output must be the same size as the
           input).

                   __kernel void copy(__write_only image2d_t destination,
                                      unsigned int index,
                                      __read_only  image2d_t source)
                   {
                       const sampler_t sampler = CLK_NORMALIZED_COORDS_FALSE;

                       int2 location = (int2)(get_global_id(0), get_global_id(1));

                       float4 value = read_imagef(source, sampler, location);

                       write_imagef(destination, location, value);
                   }

       o   Apply a simple transformation, rotating the input by an amount
           increasing with the index counter.  Pixel values are linearly
           interpolated by the sampler, and the output need not have the same
           dimensions as the input.

                   __kernel void rotate_image(__write_only image2d_t dst,
                                              unsigned int index,
                                              __read_only  image2d_t src)
                   {
                       const sampler_t sampler = (CLK_NORMALIZED_COORDS_FALSE |
                                                  CLK_FILTER_LINEAR);

                       float angle = (float)index / 100.0f;

                       float2 dst_dim = convert_float2(get_image_dim(dst));
                       float2 src_dim = convert_float2(get_image_dim(src));

                       float2 dst_cen = dst_dim / 2.0f;
                       float2 src_cen = src_dim / 2.0f;

                       int2   dst_loc = (int2)(get_global_id(0), get_global_id(1));

                       float2 dst_pos = convert_float2(dst_loc) - dst_cen;
                       float2 src_pos = {
                           cos(angle) * dst_pos.x - sin(angle) * dst_pos.y,
                           sin(angle) * dst_pos.x + cos(angle) * dst_pos.y
                       };
                       src_pos = src_pos * src_dim / dst_dim;

                       float2 src_loc = src_pos + src_cen;

                       if (src_loc.x < 0.0f      || src_loc.y < 0.0f ||
                           src_loc.x > src_dim.x || src_loc.y > src_dim.y)
                           write_imagef(dst, dst_loc, 0.5f);
                       else
                           write_imagef(dst, dst_loc, read_imagef(src, sampler, src_loc));
                   }

       o   Blend two inputs together, with the amount of each input used
           varying with the index counter.

                   __kernel void blend_images(__write_only image2d_t dst,
                                              unsigned int index,
                                              __read_only  image2d_t src1,
                                              __read_only  image2d_t src2)
                   {
                       const sampler_t sampler = (CLK_NORMALIZED_COORDS_FALSE |
                                                  CLK_FILTER_LINEAR);

                       float blend = (cos((float)index / 50.0f) + 1.0f) / 2.0f;

                       int2  dst_loc = (int2)(get_global_id(0), get_global_id(1));
                       int2 src1_loc = dst_loc * get_image_dim(src1) / get_image_dim(dst);
                       int2 src2_loc = dst_loc * get_image_dim(src2) / get_image_dim(dst);

                       float4 val1 = read_imagef(src1, sampler, src1_loc);
                       float4 val2 = read_imagef(src2, sampler, src2_loc);

                       write_imagef(dst, dst_loc, val1 * blend + val2 * (1.0f - blend));
                   }

   roberts_opencl
       Apply the Roberts cross operator
       (<https://en.wikipedia.org/wiki/Roberts_cross>) to input video stream.

       The filter accepts the following option:

       planes
           Set which planes to filter. Default value is 0xf, by which all
           planes are processed.

       scale
           Set value which will be multiplied with filtered result.  Range is
           "[0.0, 65535]" and default value is 1.0.

       delta
           Set value which will be added to filtered result.  Range is
           "[-65535, 65535]" and default value is 0.0.

       Example

       o   Apply the Roberts cross operator with scale set to 2 and delta set
           to 10

                   -i INPUT -vf "hwupload, roberts_opencl=scale=2:delta=10, hwdownload" OUTPUT

   sobel_opencl
       Apply the Sobel operator
       (<https://en.wikipedia.org/wiki/Sobel_operator>) to input video stream.

       The filter accepts the following option:

       planes
           Set which planes to filter. Default value is 0xf, by which all
           planes are processed.

       scale
           Set value which will be multiplied with filtered result.  Range is
           "[0.0, 65535]" and default value is 1.0.

       delta
           Set value which will be added to filtered result.  Range is
           "[-65535, 65535]" and default value is 0.0.

       Example

       o   Apply sobel operator with scale set to 2 and delta set to 10

                   -i INPUT -vf "hwupload, sobel_opencl=scale=2:delta=10, hwdownload" OUTPUT

   tonemap_opencl
       Perform HDR(PQ/HLG) to SDR conversion with tone-mapping.

       It accepts the following parameters:

       tonemap
           Specify the tone-mapping operator to be used. Same as tonemap
           option in tonemap.

       param
           Tune the tone mapping algorithm. same as param option in tonemap.

       desat
           Apply desaturation for highlights that exceed this level of
           brightness. The higher the parameter, the more color information
           will be preserved. This setting helps prevent unnaturally blown-out
           colors for super-highlights, by (smoothly) turning into white
           instead. This makes images feel more natural, at the cost of
           reducing information about out-of-range colors.

           The default value is 0.5, and the algorithm here is a little
           different from the cpu version tonemap currently. A setting of 0.0
           disables this option.

       threshold
           The tonemapping algorithm parameters is fine-tuned per each scene.
           And a threshold is used to detect whether the scene has changed or
           not. If the distance between the current frame average brightness
           and the current running average exceeds a threshold value, we would
           re-calculate scene average and peak brightness.  The default value
           is 0.2.

       format
           Specify the output pixel format.

           Currently supported formats are:

           p010
           nv12
       range, r
           Set the output color range.

           Possible values are:

           tv/mpeg
           pc/jpeg

           Default is same as input.

       primaries, p
           Set the output color primaries.

           Possible values are:

           bt709
           bt2020

           Default is same as input.

       transfer, t
           Set the output transfer characteristics.

           Possible values are:

           bt709
           bt2020

           Default is bt709.

       matrix, m
           Set the output colorspace matrix.

           Possible value are:

           bt709
           bt2020

           Default is same as input.

       Example

       o   Convert HDR(PQ/HLG) video to bt2020-transfer-characteristic p010
           format using linear operator.

                   -i INPUT -vf "format=p010,hwupload,tonemap_opencl=t=bt2020:tonemap=linear:format=p010,hwdownload,format=p010" OUTPUT

   unsharp_opencl
       Sharpen or blur the input video.

       It accepts the following parameters:

       luma_msize_x, lx
           Set the luma matrix horizontal size.  Range is "[1, 23]" and
           default value is 5.

       luma_msize_y, ly
           Set the luma matrix vertical size.  Range is "[1, 23]" and default
           value is 5.

       luma_amount, la
           Set the luma effect strength.  Range is "[-10, 10]" and default
           value is 1.0.

           Negative values will blur the input video, while positive values
           will sharpen it, a value of zero will disable the effect.

       chroma_msize_x, cx
           Set the chroma matrix horizontal size.  Range is "[1, 23]" and
           default value is 5.

       chroma_msize_y, cy
           Set the chroma matrix vertical size.  Range is "[1, 23]" and
           default value is 5.

       chroma_amount, ca
           Set the chroma effect strength.  Range is "[-10, 10]" and default
           value is 0.0.

           Negative values will blur the input video, while positive values
           will sharpen it, a value of zero will disable the effect.

       All parameters are optional and default to the equivalent of the string
       '5:5:1.0:5:5:0.0'.

       Examples

       o   Apply strong luma sharpen effect:

                   -i INPUT -vf "hwupload, unsharp_opencl=luma_msize_x=7:luma_msize_y=7:luma_amount=2.5, hwdownload" OUTPUT

       o   Apply a strong blur of both luma and chroma parameters:

                   -i INPUT -vf "hwupload, unsharp_opencl=7:7:-2:7:7:-2, hwdownload" OUTPUT

   xfade_opencl
       Cross fade two videos with custom transition effect by using OpenCL.

       It accepts the following options:

       transition
           Set one of possible transition effects.

           custom
               Select custom transition effect, the actual transition
               description will be picked from source and kernel options.

           fade
           wipeleft
           wiperight
           wipeup
           wipedown
           slideleft
           slideright
           slideup
           slidedown
               Default transition is fade.

       source
           OpenCL program source file for custom transition.

       kernel
           Set name of kernel to use for custom transition from program source
           file.

       duration
           Set duration of video transition.

       offset
           Set time of start of transition relative to first video.

       The program source file must contain a kernel function with the given
       name, which will be run once for each plane of the output.  Each run on
       a plane gets enqueued as a separate 2D global NDRange with one work-
       item for each pixel to be generated.  The global ID offset for each
       work-item is therefore the coordinates of a pixel in the destination
       image.

       The kernel function needs to take the following arguments:

       o   Destination image, __write_only image2d_t.

           This image will become the output; the kernel should write all of
           it.

       o   First Source image, __read_only image2d_t.  Second Source image,
           __read_only image2d_t.

           These are the most recent images on each input.  The kernel may
           read from them to generate the output, but they can't be written
           to.

       o   Transition progress, float. This value is always between 0 and 1
           inclusive.

       Example programs:

       o   Apply dots curtain transition effect:

                   __kernel void blend_images(__write_only image2d_t dst,
                                              __read_only  image2d_t src1,
                                              __read_only  image2d_t src2,
                                              float progress)
                   {
                       const sampler_t sampler = (CLK_NORMALIZED_COORDS_FALSE |
                                                  CLK_FILTER_LINEAR);
                       int2  p = (int2)(get_global_id(0), get_global_id(1));
                       float2 rp = (float2)(get_global_id(0), get_global_id(1));
                       float2 dim = (float2)(get_image_dim(src1).x, get_image_dim(src1).y);
                       rp = rp / dim;

                       float2 dots = (float2)(20.0, 20.0);
                       float2 center = (float2)(0,0);
                       float2 unused;

                       float4 val1 = read_imagef(src1, sampler, p);
                       float4 val2 = read_imagef(src2, sampler, p);
                       bool next = distance(fract(rp * dots, &unused), (float2)(0.5, 0.5)) < (progress / distance(rp, center));

                       write_imagef(dst, p, next ? val1 : val2);
                   }


VAAPI VIDEO FILTERS

       VAAPI Video filters are usually used with VAAPI decoder and VAAPI
       encoder. Below is a description of VAAPI video filters.

       To enable compilation of these filters you need to configure FFmpeg
       with "--enable-vaapi".

       To use vaapi filters, you need to setup the vaapi device correctly. For
       more information, please read
       <https://trac.ffmpeg.org/wiki/Hardware/VAAPI>

   tonemap_vaapi
       Perform HDR(High Dynamic Range) to SDR(Standard Dynamic Range)
       conversion with tone-mapping.  It maps the dynamic range of HDR10
       content to the SDR content.  It currently only accepts HDR10 as input.

       It accepts the following parameters:

       format
           Specify the output pixel format.

           Currently supported formats are:

           p010
           nv12

           Default is nv12.

       primaries, p
           Set the output color primaries.

           Default is same as input.

       transfer, t
           Set the output transfer characteristics.

           Default is bt709.

       matrix, m
           Set the output colorspace matrix.

           Default is same as input.

       Example

       o   Convert HDR(HDR10) video to bt2020-transfer-characteristic p010
           format

                   tonemap_vaapi=format=p010:t=bt2020-10


VIDEO SOURCES

       Below is a description of the currently available video sources.

   buffer
       Buffer video frames, and make them available to the filter chain.

       This source is mainly intended for a programmatic use, in particular
       through the interface defined in libavfilter/buffersrc.h.

       It accepts the following parameters:

       video_size
           Specify the size (width and height) of the buffered video frames.
           For the syntax of this option, check the "Video size" section in
           the ffmpeg-utils manual.

       width
           The input video width.

       height
           The input video height.

       pix_fmt
           A string representing the pixel format of the buffered video
           frames.  It may be a number corresponding to a pixel format, or a
           pixel format name.

       time_base
           Specify the timebase assumed by the timestamps of the buffered
           frames.

       frame_rate
           Specify the frame rate expected for the video stream.

       pixel_aspect, sar
           The sample (pixel) aspect ratio of the input video.

       sws_param
           This option is deprecated and ignored. Prepend "sws_flags=flags;"
           to the filtergraph description to specify swscale flags for
           automatically inserted scalers. See Filtergraph syntax.

       hw_frames_ctx
           When using a hardware pixel format, this should be a reference to
           an AVHWFramesContext describing input frames.

       For example:

               buffer=width=320:height=240:pix_fmt=yuv410p:time_base=1/24:sar=1

       will instruct the source to accept video frames with size 320x240 and
       with format "yuv410p", assuming 1/24 as the timestamps timebase and
       square pixels (1:1 sample aspect ratio).  Since the pixel format with
       name "yuv410p" corresponds to the number 6 (check the enum
       AVPixelFormat definition in libavutil/pixfmt.h), this example
       corresponds to:

               buffer=size=320x240:pixfmt=6:time_base=1/24:pixel_aspect=1/1

       Alternatively, the options can be specified as a flat string, but this
       syntax is deprecated:

       width:height:pix_fmt:time_base.num:time_base.den:pixel_aspect.num:pixel_aspect.den

   cellauto
       Create a pattern generated by an elementary cellular automaton.

       The initial state of the cellular automaton can be defined through the
       filename and pattern options. If such options are not specified an
       initial state is created randomly.

       At each new frame a new row in the video is filled with the result of
       the cellular automaton next generation. The behavior when the whole
       frame is filled is defined by the scroll option.

       This source accepts the following options:

       filename, f
           Read the initial cellular automaton state, i.e. the starting row,
           from the specified file.  In the file, each non-whitespace
           character is considered an alive cell, a newline will terminate the
           row, and further characters in the file will be ignored.

       pattern, p
           Read the initial cellular automaton state, i.e. the starting row,
           from the specified string.

           Each non-whitespace character in the string is considered an alive
           cell, a newline will terminate the row, and further characters in
           the string will be ignored.

       rate, r
           Set the video rate, that is the number of frames generated per
           second.  Default is 25.

       random_fill_ratio, ratio
           Set the random fill ratio for the initial cellular automaton row.
           It is a floating point number value ranging from 0 to 1, defaults
           to 1/PHI.

           This option is ignored when a file or a pattern is specified.

       random_seed, seed
           Set the seed for filling randomly the initial row, must be an
           integer included between 0 and UINT32_MAX. If not specified, or if
           explicitly set to -1, the filter will try to use a good random seed
           on a best effort basis.

       rule
           Set the cellular automaton rule, it is a number ranging from 0 to
           255.  Default value is 110.

       size, s
           Set the size of the output video. For the syntax of this option,
           check the "Video size" section in the ffmpeg-utils manual.

           If filename or pattern is specified, the size is set by default to
           the width of the specified initial state row, and the height is set
           to width * PHI.

           If size is set, it must contain the width of the specified pattern
           string, and the specified pattern will be centered in the larger
           row.

           If a filename or a pattern string is not specified, the size value
           defaults to "320x518" (used for a randomly generated initial
           state).

       scroll
           If set to 1, scroll the output upward when all the rows in the
           output have been already filled. If set to 0, the new generated row
           will be written over the top row just after the bottom row is
           filled.  Defaults to 1.

       start_full, full
           If set to 1, completely fill the output with generated rows before
           outputting the first frame.  This is the default behavior, for
           disabling set the value to 0.

       stitch
           If set to 1, stitch the left and right row edges together.  This is
           the default behavior, for disabling set the value to 0.

       Examples

       o   Read the initial state from pattern, and specify an output of size
           200x400.

                   cellauto=f=pattern:s=200x400

       o   Generate a random initial row with a width of 200 cells, with a
           fill ratio of 2/3:

                   cellauto=ratio=2/3:s=200x200

       o   Create a pattern generated by rule 18 starting by a single alive
           cell centered on an initial row with width 100:

                   cellauto=p=@s=100x400:full=0:rule=18

       o   Specify a more elaborated initial pattern:

                   cellauto=p='@@ @ @@':s=100x400:full=0:rule=18

   coreimagesrc
       Video source generated on GPU using Apple's CoreImage API on OSX.

       This video source is a specialized version of the coreimage video
       filter.  Use a core image generator at the beginning of the applied
       filterchain to generate the content.

       The coreimagesrc video source accepts the following options:

       list_generators
           List all available generators along with all their respective
           options as well as possible minimum and maximum values along with
           the default values.

                   list_generators=true

       size, s
           Specify the size of the sourced video. For the syntax of this
           option, check the "Video size" section in the ffmpeg-utils manual.
           The default value is "320x240".

       rate, r
           Specify the frame rate of the sourced video, as the number of
           frames generated per second. It has to be a string in the format
           frame_rate_num/frame_rate_den, an integer number, a floating point
           number or a valid video frame rate abbreviation. The default value
           is "25".

       sar Set the sample aspect ratio of the sourced video.

       duration, d
           Set the duration of the sourced video. See the Time duration
           section in the ffmpeg-utils(1) manual for the accepted syntax.

           If not specified, or the expressed duration is negative, the video
           is supposed to be generated forever.

       Additionally, all options of the coreimage video filter are accepted.
       A complete filterchain can be used for further processing of the
       generated input without CPU-HOST transfer. See coreimage documentation
       and examples for details.

       Examples

       o   Use CIQRCodeGenerator to create a QR code for the FFmpeg homepage,
           given as complete and escaped command-line for Apple's standard
           bash shell:

                   ffmpeg -f lavfi -i coreimagesrc=s=100x100:filter=CIQRCodeGenerator@inputMessage=https\\\\\://FFmpeg.org/@inputCorrectionLevel=H -frames:v 1 QRCode.png

           This example is equivalent to the QRCode example of coreimage
           without the need for a nullsrc video source.

   gradients
       Generate several gradients.

       size, s
           Set frame size. For the syntax of this option, check the "Video
           size" section in the ffmpeg-utils manual. Default value is
           "640x480".

       rate, r
           Set frame rate, expressed as number of frames per second. Default
           value is "25".

       c0, c1, c2, c3, c4, c5, c6, c7
           Set 8 colors. Default values for colors is to pick random one.

       x0, y0, y0, y1
           Set gradient line source and destination points. If negative or out
           of range, random ones are picked.

       nb_colors, n
           Set number of colors to use at once. Allowed range is from 2 to 8.
           Default value is 2.

       seed
           Set seed for picking gradient line points.

       duration, d
           Set the duration of the sourced video. See the Time duration
           section in the ffmpeg-utils(1) manual for the accepted syntax.

           If not specified, or the expressed duration is negative, the video
           is supposed to be generated forever.

       speed
           Set speed of gradients rotation.

   mandelbrot
       Generate a Mandelbrot set fractal, and progressively zoom towards the
       point specified with start_x and start_y.

       This source accepts the following options:

       end_pts
           Set the terminal pts value. Default value is 400.

       end_scale
           Set the terminal scale value.  Must be a floating point value.
           Default value is 0.3.

       inner
           Set the inner coloring mode, that is the algorithm used to draw the
           Mandelbrot fractal internal region.

           It shall assume one of the following values:

           black
               Set black mode.

           convergence
               Show time until convergence.

           mincol
               Set color based on point closest to the origin of the
               iterations.

           period
               Set period mode.

           Default value is mincol.

       bailout
           Set the bailout value. Default value is 10.0.

       maxiter
           Set the maximum of iterations performed by the rendering algorithm.
           Default value is 7189.

       outer
           Set outer coloring mode.  It shall assume one of following values:

           iteration_count
               Set iteration count mode.

           normalized_iteration_count
               set normalized iteration count mode.

           Default value is normalized_iteration_count.

       rate, r
           Set frame rate, expressed as number of frames per second. Default
           value is "25".

       size, s
           Set frame size. For the syntax of this option, check the "Video
           size" section in the ffmpeg-utils manual. Default value is
           "640x480".

       start_scale
           Set the initial scale value. Default value is 3.0.

       start_x
           Set the initial x position. Must be a floating point value between
           -100 and 100. Default value is
           -0.743643887037158704752191506114774.

       start_y
           Set the initial y position. Must be a floating point value between
           -100 and 100. Default value is
           -0.131825904205311970493132056385139.

   mptestsrc
       Generate various test patterns, as generated by the MPlayer test
       filter.

       The size of the generated video is fixed, and is 256x256.  This source
       is useful in particular for testing encoding features.

       This source accepts the following options:

       rate, r
           Specify the frame rate of the sourced video, as the number of
           frames generated per second. It has to be a string in the format
           frame_rate_num/frame_rate_den, an integer number, a floating point
           number or a valid video frame rate abbreviation. The default value
           is "25".

       duration, d
           Set the duration of the sourced video. See the Time duration
           section in the ffmpeg-utils(1) manual for the accepted syntax.

           If not specified, or the expressed duration is negative, the video
           is supposed to be generated forever.

       test, t
           Set the number or the name of the test to perform. Supported tests
           are:

           dc_luma
           dc_chroma
           freq_luma
           freq_chroma
           amp_luma
           amp_chroma
           cbp
           mv
           ring1
           ring2
           all
           max_frames, m
               Set the maximum number of frames generated for each test,
               default value is 30.

           Default value is "all", which will cycle through the list of all
           tests.

       Some examples:

               mptestsrc=t=dc_luma

       will generate a "dc_luma" test pattern.

   frei0r_src
       Provide a frei0r source.

       To enable compilation of this filter you need to install the frei0r
       header and configure FFmpeg with "--enable-frei0r".

       This source accepts the following parameters:

       size
           The size of the video to generate. For the syntax of this option,
           check the "Video size" section in the ffmpeg-utils manual.

       framerate
           The framerate of the generated video. It may be a string of the
           form num/den or a frame rate abbreviation.

       filter_name
           The name to the frei0r source to load. For more information
           regarding frei0r and how to set the parameters, read the frei0r
           section in the video filters documentation.

       filter_params
           A '|'-separated list of parameters to pass to the frei0r source.

       For example, to generate a frei0r partik0l source with size 200x200 and
       frame rate 10 which is overlaid on the overlay filter main input:

               frei0r_src=size=200x200:framerate=10:filter_name=partik0l:filter_params=1234 [overlay]; [in][overlay] overlay

   life
       Generate a life pattern.

       This source is based on a generalization of John Conway's life game.

       The sourced input represents a life grid, each pixel represents a cell
       which can be in one of two possible states, alive or dead. Every cell
       interacts with its eight neighbours, which are the cells that are
       horizontally, vertically, or diagonally adjacent.

       At each interaction the grid evolves according to the adopted rule,
       which specifies the number of neighbor alive cells which will make a
       cell stay alive or born. The rule option allows one to specify the rule
       to adopt.

       This source accepts the following options:

       filename, f
           Set the file from which to read the initial grid state. In the
           file, each non-whitespace character is considered an alive cell,
           and newline is used to delimit the end of each row.

           If this option is not specified, the initial grid is generated
           randomly.

       rate, r
           Set the video rate, that is the number of frames generated per
           second.  Default is 25.

       random_fill_ratio, ratio
           Set the random fill ratio for the initial random grid. It is a
           floating point number value ranging from 0 to 1, defaults to 1/PHI.
           It is ignored when a file is specified.

       random_seed, seed
           Set the seed for filling the initial random grid, must be an
           integer included between 0 and UINT32_MAX. If not specified, or if
           explicitly set to -1, the filter will try to use a good random seed
           on a best effort basis.

       rule
           Set the life rule.

           A rule can be specified with a code of the kind "SNS/BNB", where NS
           and NB are sequences of numbers in the range 0-8, NS specifies the
           number of alive neighbor cells which make a live cell stay alive,
           and NB the number of alive neighbor cells which make a dead cell to
           become alive (i.e. to "born").  "s" and "b" can be used in place of
           "S" and "B", respectively.

           Alternatively a rule can be specified by an 18-bits integer. The 9
           high order bits are used to encode the next cell state if it is
           alive for each number of neighbor alive cells, the low order bits
           specify the rule for "borning" new cells. Higher order bits encode
           for an higher number of neighbor cells.  For example the number
           6153 = "(12<<9)+9" specifies a stay alive rule of 12 and a born
           rule of 9, which corresponds to "S23/B03".

           Default value is "S23/B3", which is the original Conway's game of
           life rule, and will keep a cell alive if it has 2 or 3 neighbor
           alive cells, and will born a new cell if there are three alive
           cells around a dead cell.

       size, s
           Set the size of the output video. For the syntax of this option,
           check the "Video size" section in the ffmpeg-utils manual.

           If filename is specified, the size is set by default to the same
           size of the input file. If size is set, it must contain the size
           specified in the input file, and the initial grid defined in that
           file is centered in the larger resulting area.

           If a filename is not specified, the size value defaults to
           "320x240" (used for a randomly generated initial grid).

       stitch
           If set to 1, stitch the left and right grid edges together, and the
           top and bottom edges also. Defaults to 1.

       mold
           Set cell mold speed. If set, a dead cell will go from death_color
           to mold_color with a step of mold. mold can have a value from 0 to
           255.

       life_color
           Set the color of living (or new born) cells.

       death_color
           Set the color of dead cells. If mold is set, this is the first
           color used to represent a dead cell.

       mold_color
           Set mold color, for definitely dead and moldy cells.

           For the syntax of these 3 color options, check the "Color" section
           in the ffmpeg-utils manual.

       Examples

       o   Read a grid from pattern, and center it on a grid of size 300x300
           pixels:

                   life=f=pattern:s=300x300

       o   Generate a random grid of size 200x200, with a fill ratio of 2/3:

                   life=ratio=2/3:s=200x200

       o   Specify a custom rule for evolving a randomly generated grid:

                   life=rule=S14/B34

       o   Full example with slow death effect (mold) using ffplay:

                   ffplay -f lavfi life=s=300x200:mold=10:r=60:ratio=0.1:death_color=#C83232:life_color=#00ff00,scale=1200:800:flags=16

   allrgb, allyuv, color, haldclutsrc, nullsrc, pal75bars, pal100bars,
       rgbtestsrc, smptebars, smptehdbars, testsrc, testsrc2, yuvtestsrc
       The "allrgb" source returns frames of size 4096x4096 of all rgb colors.

       The "allyuv" source returns frames of size 4096x4096 of all yuv colors.

       The "color" source provides an uniformly colored input.

       The "haldclutsrc" source provides an identity Hald CLUT. See also
       haldclut filter.

       The "nullsrc" source returns unprocessed video frames. It is mainly
       useful to be employed in analysis / debugging tools, or as the source
       for filters which ignore the input data.

       The "pal75bars" source generates a color bars pattern, based on EBU PAL
       recommendations with 75% color levels.

       The "pal100bars" source generates a color bars pattern, based on EBU
       PAL recommendations with 100% color levels.

       The "rgbtestsrc" source generates an RGB test pattern useful for
       detecting RGB vs BGR issues. You should see a red, green and blue
       stripe from top to bottom.

       The "smptebars" source generates a color bars pattern, based on the
       SMPTE Engineering Guideline EG 1-1990.

       The "smptehdbars" source generates a color bars pattern, based on the
       SMPTE RP 219-2002.

       The "testsrc" source generates a test video pattern, showing a color
       pattern, a scrolling gradient and a timestamp. This is mainly intended
       for testing purposes.

       The "testsrc2" source is similar to testsrc, but supports more pixel
       formats instead of just "rgb24". This allows using it as an input for
       other tests without requiring a format conversion.

       The "yuvtestsrc" source generates an YUV test pattern. You should see a
       y, cb and cr stripe from top to bottom.

       The sources accept the following parameters:

       level
           Specify the level of the Hald CLUT, only available in the
           "haldclutsrc" source. A level of "N" generates a picture of "N*N*N"
           by "N*N*N" pixels to be used as identity matrix for 3D lookup
           tables. Each component is coded on a "1/(N*N)" scale.

       color, c
           Specify the color of the source, only available in the "color"
           source. For the syntax of this option, check the "Color" section in
           the ffmpeg-utils manual.

       size, s
           Specify the size of the sourced video. For the syntax of this
           option, check the "Video size" section in the ffmpeg-utils manual.
           The default value is "320x240".

           This option is not available with the "allrgb", "allyuv", and
           "haldclutsrc" filters.

       rate, r
           Specify the frame rate of the sourced video, as the number of
           frames generated per second. It has to be a string in the format
           frame_rate_num/frame_rate_den, an integer number, a floating point
           number or a valid video frame rate abbreviation. The default value
           is "25".

       duration, d
           Set the duration of the sourced video. See the Time duration
           section in the ffmpeg-utils(1) manual for the accepted syntax.

           If not specified, or the expressed duration is negative, the video
           is supposed to be generated forever.

           Since the frame rate is used as time base, all frames including the
           last one will have their full duration. If the specified duration
           is not a multiple of the frame duration, it will be rounded up.

       sar Set the sample aspect ratio of the sourced video.

       alpha
           Specify the alpha (opacity) of the background, only available in
           the "testsrc2" source. The value must be between 0 (fully
           transparent) and 255 (fully opaque, the default).

       decimals, n
           Set the number of decimals to show in the timestamp, only available
           in the "testsrc" source.

           The displayed timestamp value will correspond to the original
           timestamp value multiplied by the power of 10 of the specified
           value. Default value is 0.

       Examples

       o   Generate a video with a duration of 5.3 seconds, with size 176x144
           and a frame rate of 10 frames per second:

                   testsrc=duration=5.3:size=qcif:rate=10

       o   The following graph description will generate a red source with an
           opacity of 0.2, with size "qcif" and a frame rate of 10 frames per
           second:

                   color=c=red@0.2:s=qcif:r=10

       o   If the input content is to be ignored, "nullsrc" can be used. The
           following command generates noise in the luminance plane by
           employing the "geq" filter:

                   nullsrc=s=256x256, geq=random(1)*255:128:128

       Commands

       The "color" source supports the following commands:

       c, color
           Set the color of the created image. Accepts the same syntax of the
           corresponding color option.

   openclsrc
       Generate video using an OpenCL program.

       source
           OpenCL program source file.

       kernel
           Kernel name in program.

       size, s
           Size of frames to generate.  This must be set.

       format
           Pixel format to use for the generated frames.  This must be set.

       rate, r
           Number of frames generated every second.  Default value is '25'.

       For details of how the program loading works, see the program_opencl
       filter.

       Example programs:

       o   Generate a colour ramp by setting pixel values from the position of
           the pixel in the output image.  (Note that this will work with all
           pixel formats, but the generated output will not be the same.)

                   __kernel void ramp(__write_only image2d_t dst,
                                      unsigned int index)
                   {
                       int2 loc = (int2)(get_global_id(0), get_global_id(1));

                       float4 val;
                       val.xy = val.zw = convert_float2(loc) / convert_float2(get_image_dim(dst));

                       write_imagef(dst, loc, val);
                   }

       o   Generate a Sierpinski carpet pattern, panning by a single pixel
           each frame.

                   __kernel void sierpinski_carpet(__write_only image2d_t dst,
                                                   unsigned int index)
                   {
                       int2 loc = (int2)(get_global_id(0), get_global_id(1));

                       float4 value = 0.0f;
                       int x = loc.x + index;
                       int y = loc.y + index;
                       while (x > 0 || y > 0) {
                           if (x % 3 == 1 && y % 3 == 1) {
                               value = 1.0f;
                               break;
                           }
                           x /= 3;
                           y /= 3;
                       }

                       write_imagef(dst, loc, value);
                   }

   sierpinski
       Generate a Sierpinski carpet/triangle fractal, and randomly pan around.

       This source accepts the following options:

       size, s
           Set frame size. For the syntax of this option, check the "Video
           size" section in the ffmpeg-utils manual. Default value is
           "640x480".

       rate, r
           Set frame rate, expressed as number of frames per second. Default
           value is "25".

       seed
           Set seed which is used for random panning.

       jump
           Set max jump for single pan destination. Allowed range is from 1 to
           10000.

       type
           Set fractal type, can be default "carpet" or "triangle".


VIDEO SINKS

       Below is a description of the currently available video sinks.

   buffersink
       Buffer video frames, and make them available to the end of the filter
       graph.

       This sink is mainly intended for programmatic use, in particular
       through the interface defined in libavfilter/buffersink.h or the
       options system.

       It accepts a pointer to an AVBufferSinkContext structure, which defines
       the incoming buffers' formats, to be passed as the opaque parameter to
       "avfilter_init_filter" for initialization.

   nullsink
       Null video sink: do absolutely nothing with the input video. It is
       mainly useful as a template and for use in analysis / debugging tools.


MULTIMEDIA FILTERS

       Below is a description of the currently available multimedia filters.

   abitscope
       Convert input audio to a video output, displaying the audio bit scope.

       The filter accepts the following options:

       rate, r
           Set frame rate, expressed as number of frames per second. Default
           value is "25".

       size, s
           Specify the video size for the output. For the syntax of this
           option, check the "Video size" section in the ffmpeg-utils manual.
           Default value is "1024x256".

       colors
           Specify list of colors separated by space or by '|' which will be
           used to draw channels. Unrecognized or missing colors will be
           replaced by white color.

   adrawgraph
       Draw a graph using input audio metadata.

       See drawgraph

   agraphmonitor
       See graphmonitor.

   ahistogram
       Convert input audio to a video output, displaying the volume histogram.

       The filter accepts the following options:

       dmode
           Specify how histogram is calculated.

           It accepts the following values:

           single
               Use single histogram for all channels.

           separate
               Use separate histogram for each channel.

           Default is "single".

       rate, r
           Set frame rate, expressed as number of frames per second. Default
           value is "25".

       size, s
           Specify the video size for the output. For the syntax of this
           option, check the "Video size" section in the ffmpeg-utils manual.
           Default value is "hd720".

       scale
           Set display scale.

           It accepts the following values:

           log logarithmic

           sqrt
               square root

           cbrt
               cubic root

           lin linear

           rlog
               reverse logarithmic

           Default is "log".

       ascale
           Set amplitude scale.

           It accepts the following values:

           log logarithmic

           lin linear

           Default is "log".

       acount
           Set how much frames to accumulate in histogram.  Default is 1.
           Setting this to -1 accumulates all frames.

       rheight
           Set histogram ratio of window height.

       slide
           Set sonogram sliding.

           It accepts the following values:

           replace
               replace old rows with new ones.

           scroll
               scroll from top to bottom.

           Default is "replace".

   aphasemeter
       Measures phase of input audio, which is exported as metadata
       "lavfi.aphasemeter.phase", representing mean phase of current audio
       frame. A video output can also be produced and is enabled by default.
       The audio is passed through as first output.

       Audio will be rematrixed to stereo if it has a different channel
       layout. Phase value is in range "[-1, 1]" where "-1" means left and
       right channels are completely out of phase and 1 means channels are in
       phase.

       The filter accepts the following options, all related to its video
       output:

       rate, r
           Set the output frame rate. Default value is 25.

       size, s
           Set the video size for the output. For the syntax of this option,
           check the "Video size" section in the ffmpeg-utils manual.  Default
           value is "800x400".

       rc
       gc
       bc  Specify the red, green, blue contrast. Default values are 2, 7 and
           1.  Allowed range is "[0, 255]".

       mpc Set color which will be used for drawing median phase. If color is
           "none" which is default, no median phase value will be drawn.

       video
           Enable video output. Default is enabled.

       phasing detection

       The filter also detects out of phase and mono sequences in stereo
       streams.  It logs the sequence start, end and duration when it lasts
       longer or as long as the minimum set.

       The filter accepts the following options for this detection:

       phasing
           Enable mono and out of phase detection. Default is disabled.

       tolerance, t
           Set phase tolerance for mono detection, in amplitude ratio. Default
           is 0.  Allowed range is "[0, 1]".

       angle, a
           Set angle threshold for out of phase detection, in degree. Default
           is 170.  Allowed range is "[90, 180]".

       duration, d
           Set mono or out of phase duration until notification, expressed in
           seconds. Default is 2.

       Examples

       o   Complete example with ffmpeg to detect 1 second of mono with 0.001
           phase tolerance:

                   ffmpeg -i stereo.wav -af aphasemeter=video=0:phasing=1:duration=1:tolerance=0.001 -f null -

   avectorscope
       Convert input audio to a video output, representing the audio vector
       scope.

       The filter is used to measure the difference between channels of stereo
       audio stream. A monaural signal, consisting of identical left and right
       signal, results in straight vertical line. Any stereo separation is
       visible as a deviation from this line, creating a Lissajous figure.  If
       the straight (or deviation from it) but horizontal line appears this
       indicates that the left and right channels are out of phase.

       The filter accepts the following options:

       mode, m
           Set the vectorscope mode.

           Available values are:

           lissajous
               Lissajous rotated by 45 degrees.

           lissajous_xy
               Same as above but not rotated.

           polar
               Shape resembling half of circle.

           Default value is lissajous.

       size, s
           Set the video size for the output. For the syntax of this option,
           check the "Video size" section in the ffmpeg-utils manual.  Default
           value is "400x400".

       rate, r
           Set the output frame rate. Default value is 25.

       rc
       gc
       bc
       ac  Specify the red, green, blue and alpha contrast. Default values are
           40, 160, 80 and 255.  Allowed range is "[0, 255]".

       rf
       gf
       bf
       af  Specify the red, green, blue and alpha fade. Default values are 15,
           10, 5 and 5.  Allowed range is "[0, 255]".

       zoom
           Set the zoom factor. Default value is 1. Allowed range is "[0,
           10]".  Values lower than 1 will auto adjust zoom factor to maximal
           possible value.

       draw
           Set the vectorscope drawing mode.

           Available values are:

           dot Draw dot for each sample.

           line
               Draw line between previous and current sample.

           Default value is dot.

       scale
           Specify amplitude scale of audio samples.

           Available values are:

           lin Linear.

           sqrt
               Square root.

           cbrt
               Cubic root.

           log Logarithmic.

       swap
           Swap left channel axis with right channel axis.

       mirror
           Mirror axis.

           none
               No mirror.

           x   Mirror only x axis.

           y   Mirror only y axis.

           xy  Mirror both axis.

       Examples

       o   Complete example using ffplay:

                   ffplay -f lavfi 'amovie=input.mp3, asplit [a][out1];
                                [a] avectorscope=zoom=1.3:rc=2:gc=200:bc=10:rf=1:gf=8:bf=7 [out0]'

   bench, abench
       Benchmark part of a filtergraph.

       The filter accepts the following options:

       action
           Start or stop a timer.

           Available values are:

           start
               Get the current time, set it as frame metadata (using the key
               "lavfi.bench.start_time"), and forward the frame to the next
               filter.

           stop
               Get the current time and fetch the "lavfi.bench.start_time"
               metadata from the input frame metadata to get the time
               difference. Time difference, average, maximum and minimum time
               (respectively "t", "avg", "max" and "min") are then printed.
               The timestamps are expressed in seconds.

       Examples

       o   Benchmark selectivecolor filter:

                   bench=start,selectivecolor=reds=-.2 .12 -.49,bench=stop

   concat
       Concatenate audio and video streams, joining them together one after
       the other.

       The filter works on segments of synchronized video and audio streams.
       All segments must have the same number of streams of each type, and
       that will also be the number of streams at output.

       The filter accepts the following options:

       n   Set the number of segments. Default is 2.

       v   Set the number of output video streams, that is also the number of
           video streams in each segment. Default is 1.

       a   Set the number of output audio streams, that is also the number of
           audio streams in each segment. Default is 0.

       unsafe
           Activate unsafe mode: do not fail if segments have a different
           format.

       The filter has v+a outputs: first v video outputs, then a audio
       outputs.

       There are nx(v+a) inputs: first the inputs for the first segment, in
       the same order as the outputs, then the inputs for the second segment,
       etc.

       Related streams do not always have exactly the same duration, for
       various reasons including codec frame size or sloppy authoring. For
       that reason, related synchronized streams (e.g. a video and its audio
       track) should be concatenated at once. The concat filter will use the
       duration of the longest stream in each segment (except the last one),
       and if necessary pad shorter audio streams with silence.

       For this filter to work correctly, all segments must start at timestamp
       0.

       All corresponding streams must have the same parameters in all
       segments; the filtering system will automatically select a common pixel
       format for video streams, and a common sample format, sample rate and
       channel layout for audio streams, but other settings, such as
       resolution, must be converted explicitly by the user.

       Different frame rates are acceptable but will result in variable frame
       rate at output; be sure to configure the output file to handle it.

       Examples

       o   Concatenate an opening, an episode and an ending, all in bilingual
           version (video in stream 0, audio in streams 1 and 2):

                   ffmpeg -i opening.mkv -i episode.mkv -i ending.mkv -filter_complex \
                     '[0:0] [0:1] [0:2] [1:0] [1:1] [1:2] [2:0] [2:1] [2:2]
                      concat=n=3:v=1:a=2 [v] [a1] [a2]' \
                     -map '[v]' -map '[a1]' -map '[a2]' output.mkv

       o   Concatenate two parts, handling audio and video separately, using
           the (a)movie sources, and adjusting the resolution:

                   movie=part1.mp4, scale=512:288 [v1] ; amovie=part1.mp4 [a1] ;
                   movie=part2.mp4, scale=512:288 [v2] ; amovie=part2.mp4 [a2] ;
                   [v1] [v2] concat [outv] ; [a1] [a2] concat=v=0:a=1 [outa]

           Note that a desync will happen at the stitch if the audio and video
           streams do not have exactly the same duration in the first file.

       Commands

       This filter supports the following commands:

       next
           Close the current segment and step to the next one

   ebur128
       EBU R128 scanner filter. This filter takes an audio stream and analyzes
       its loudness level. By default, it logs a message at a frequency of
       10Hz with the Momentary loudness (identified by "M"), Short-term
       loudness ("S"), Integrated loudness ("I") and Loudness Range ("LRA").

       The filter can only analyze streams which have a sampling rate of 48000
       Hz and whose sample format is double-precision floating point. The
       input stream will be converted to this specification, if needed. Users
       may need to insert aformat and/or aresample filters after this filter
       to obtain the original parameters.

       The filter also has a video output (see the video option) with a real
       time graph to observe the loudness evolution. The graphic contains the
       logged message mentioned above, so it is not printed anymore when this
       option is set, unless the verbose logging is set. The main graphing
       area contains the short-term loudness (3 seconds of analysis), and the
       gauge on the right is for the momentary loudness (400 milliseconds),
       but can optionally be configured to instead display short-term loudness
       (see gauge).

       The green area marks a  +/- 1LU target range around the target loudness
       (-23LUFS by default, unless modified through target).

       More information about the Loudness Recommendation EBU R128 on
       <http://tech.ebu.ch/loudness>.

       The filter accepts the following options:

       video
           Activate the video output. The audio stream is passed unchanged
           whether this option is set or no. The video stream will be the
           first output stream if activated. Default is 0.

       size
           Set the video size. This option is for video only. For the syntax
           of this option, check the "Video size" section in the ffmpeg-utils
           manual.  Default and minimum resolution is "640x480".

       meter
           Set the EBU scale meter. Default is 9. Common values are 9 and 18,
           respectively for EBU scale meter +9 and EBU scale meter +18. Any
           other integer value between this range is allowed.

       metadata
           Set metadata injection. If set to 1, the audio input will be
           segmented into 100ms output frames, each of them containing various
           loudness information in metadata.  All the metadata keys are
           prefixed with "lavfi.r128.".

           Default is 0.

       framelog
           Force the frame logging level.

           Available values are:

           info
               information logging level

           verbose
               verbose logging level

           By default, the logging level is set to info. If the video or the
           metadata options are set, it switches to verbose.

       peak
           Set peak mode(s).

           Available modes can be cumulated (the option is a "flag" type).
           Possible values are:

           none
               Disable any peak mode (default).

           sample
               Enable sample-peak mode.

               Simple peak mode looking for the higher sample value. It logs a
               message for sample-peak (identified by "SPK").

           true
               Enable true-peak mode.

               If enabled, the peak lookup is done on an over-sampled version
               of the input stream for better peak accuracy. It logs a message
               for true-peak.  (identified by "TPK") and true-peak per frame
               (identified by "FTPK").  This mode requires a build with
               "libswresample".

       dualmono
           Treat mono input files as "dual mono". If a mono file is intended
           for playback on a stereo system, its EBU R128 measurement will be
           perceptually incorrect.  If set to "true", this option will
           compensate for this effect.  Multi-channel input files are not
           affected by this option.

       panlaw
           Set a specific pan law to be used for the measurement of dual mono
           files.  This parameter is optional, and has a default value of
           -3.01dB.

       target
           Set a specific target level (in LUFS) used as relative zero in the
           visualization.  This parameter is optional and has a default value
           of -23LUFS as specified by EBU R128. However, material published
           online may prefer a level of -16LUFS (e.g. for use with podcasts or
           video platforms).

       gauge
           Set the value displayed by the gauge. Valid values are "momentary"
           and s "shortterm". By default the momentary value will be used, but
           in certain scenarios it may be more useful to observe the short
           term value instead (e.g.  live mixing).

       scale
           Sets the display scale for the loudness. Valid parameters are
           "absolute" (in LUFS) or "relative" (LU) relative to the target.
           This only affects the video output, not the summary or continuous
           log output.

       Examples

       o   Real-time graph using ffplay, with a EBU scale meter +18:

                   ffplay -f lavfi -i "amovie=input.mp3,ebur128=video=1:meter=18 [out0][out1]"

       o   Run an analysis with ffmpeg:

                   ffmpeg -nostats -i input.mp3 -filter_complex ebur128 -f null -

   interleave, ainterleave
       Temporally interleave frames from several inputs.

       "interleave" works with video inputs, "ainterleave" with audio.

       These filters read frames from several inputs and send the oldest
       queued frame to the output.

       Input streams must have well defined, monotonically increasing frame
       timestamp values.

       In order to submit one frame to output, these filters need to enqueue
       at least one frame for each input, so they cannot work in case one
       input is not yet terminated and will not receive incoming frames.

       For example consider the case when one input is a "select" filter which
       always drops input frames. The "interleave" filter will keep reading
       from that input, but it will never be able to send new frames to output
       until the input sends an end-of-stream signal.

       Also, depending on inputs synchronization, the filters will drop frames
       in case one input receives more frames than the other ones, and the
       queue is already filled.

       These filters accept the following options:

       nb_inputs, n
           Set the number of different inputs, it is 2 by default.

       duration
           How to determine the end-of-stream.

           longest
               The duration of the longest input. (default)

           shortest
               The duration of the shortest input.

           first
               The duration of the first input.

       Examples

       o   Interleave frames belonging to different streams using ffmpeg:

                   ffmpeg -i bambi.avi -i pr0n.mkv -filter_complex "[0:v][1:v] interleave" out.avi

       o   Add flickering blur effect:

                   select='if(gt(random(0), 0.2), 1, 2)':n=2 [tmp], boxblur=2:2, [tmp] interleave

   metadata, ametadata
       Manipulate frame metadata.

       This filter accepts the following options:

       mode
           Set mode of operation of the filter.

           Can be one of the following:

           select
               If both "value" and "key" is set, select frames which have such
               metadata. If only "key" is set, select every frame that has
               such key in metadata.

           add Add new metadata "key" and "value". If key is already available
               do nothing.

           modify
               Modify value of already present key.

           delete
               If "value" is set, delete only keys that have such value.
               Otherwise, delete key. If "key" is not set, delete all metadata
               values in the frame.

           print
               Print key and its value if metadata was found. If "key" is not
               set print all metadata values available in frame.

       key Set key used with all modes. Must be set for all modes except
           "print" and "delete".

       value
           Set metadata value which will be used. This option is mandatory for
           "modify" and "add" mode.

       function
           Which function to use when comparing metadata value and "value".

           Can be one of following:

           same_str
               Values are interpreted as strings, returns true if metadata
               value is same as "value".

           starts_with
               Values are interpreted as strings, returns true if metadata
               value starts with the "value" option string.

           less
               Values are interpreted as floats, returns true if metadata
               value is less than "value".

           equal
               Values are interpreted as floats, returns true if "value" is
               equal with metadata value.

           greater
               Values are interpreted as floats, returns true if metadata
               value is greater than "value".

           expr
               Values are interpreted as floats, returns true if expression
               from option "expr" evaluates to true.

           ends_with
               Values are interpreted as strings, returns true if metadata
               value ends with the "value" option string.

       expr
           Set expression which is used when "function" is set to "expr".  The
           expression is evaluated through the eval API and can contain the
           following constants:

           VALUE1
               Float representation of "value" from metadata key.

           VALUE2
               Float representation of "value" as supplied by user in "value"
               option.

       file
           If specified in "print" mode, output is written to the named file.
           Instead of plain filename any writable url can be specified.
           Filename ``-'' is a shorthand for standard output. If "file" option
           is not set, output is written to the log with AV_LOG_INFO loglevel.

       direct
           Reduces buffering in print mode when output is written to a URL set
           using file.

       Examples

       o   Print all metadata values for frames with key
           "lavfi.signalstats.YDIF" with values between 0 and 1.

                   signalstats,metadata=print:key=lavfi.signalstats.YDIF:value=0:function=expr:expr='between(VALUE1,0,1)'

       o   Print silencedetect output to file metadata.txt.

                   silencedetect,ametadata=mode=print:file=metadata.txt

       o   Direct all metadata to a pipe with file descriptor 4.

                   metadata=mode=print:file='pipe\:4'

   perms, aperms
       Set read/write permissions for the output frames.

       These filters are mainly aimed at developers to test direct path in the
       following filter in the filtergraph.

       The filters accept the following options:

       mode
           Select the permissions mode.

           It accepts the following values:

           none
               Do nothing. This is the default.

           ro  Set all the output frames read-only.

           rw  Set all the output frames directly writable.

           toggle
               Make the frame read-only if writable, and writable if read-
               only.

           random
               Set each output frame read-only or writable randomly.

       seed
           Set the seed for the random mode, must be an integer included
           between 0 and "UINT32_MAX". If not specified, or if explicitly set
           to "-1", the filter will try to use a good random seed on a best
           effort basis.

       Note: in case of auto-inserted filter between the permission filter and
       the following one, the permission might not be received as expected in
       that following filter. Inserting a format or aformat filter before the
       perms/aperms filter can avoid this problem.

   realtime, arealtime
       Slow down filtering to match real time approximately.

       These filters will pause the filtering for a variable amount of time to
       match the output rate with the input timestamps.  They are similar to
       the re option to "ffmpeg".

       They accept the following options:

       limit
           Time limit for the pauses. Any pause longer than that will be
           considered a timestamp discontinuity and reset the timer. Default
           is 2 seconds.

       speed
           Speed factor for processing. The value must be a float larger than
           zero.  Values larger than 1.0 will result in faster than realtime
           processing, smaller will slow processing down. The limit is
           automatically adapted accordingly. Default is 1.0.

           A processing speed faster than what is possible without these
           filters cannot be achieved.

   select, aselect
       Select frames to pass in output.

       This filter accepts the following options:

       expr, e
           Set expression, which is evaluated for each input frame.

           If the expression is evaluated to zero, the frame is discarded.

           If the evaluation result is negative or NaN, the frame is sent to
           the first output; otherwise it is sent to the output with index
           "ceil(val)-1", assuming that the input index starts from 0.

           For example a value of 1.2 corresponds to the output with index
           "ceil(1.2)-1 = 2-1 = 1", that is the second output.

       outputs, n
           Set the number of outputs. The output to which to send the selected
           frame is based on the result of the evaluation. Default value is 1.

       The expression can contain the following constants:

       n   The (sequential) number of the filtered frame, starting from 0.

       selected_n
           The (sequential) number of the selected frame, starting from 0.

       prev_selected_n
           The sequential number of the last selected frame. It's NAN if
           undefined.

       TB  The timebase of the input timestamps.

       pts The PTS (Presentation TimeStamp) of the filtered video frame,
           expressed in TB units. It's NAN if undefined.

       t   The PTS of the filtered video frame, expressed in seconds. It's NAN
           if undefined.

       prev_pts
           The PTS of the previously filtered video frame. It's NAN if
           undefined.

       prev_selected_pts
           The PTS of the last previously filtered video frame. It's NAN if
           undefined.

       prev_selected_t
           The PTS of the last previously selected video frame, expressed in
           seconds. It's NAN if undefined.

       start_pts
           The PTS of the first video frame in the video. It's NAN if
           undefined.

       start_t
           The time of the first video frame in the video. It's NAN if
           undefined.

       pict_type (video only)
           The type of the filtered frame. It can assume one of the following
           values:

           I
           P
           B
           S
           SI
           SP
           BI
       interlace_type (video only)
           The frame interlace type. It can assume one of the following
           values:

           PROGRESSIVE
               The frame is progressive (not interlaced).

           TOPFIRST
               The frame is top-field-first.

           BOTTOMFIRST
               The frame is bottom-field-first.

       consumed_sample_n (audio only)
           the number of selected samples before the current frame

       samples_n (audio only)
           the number of samples in the current frame

       sample_rate (audio only)
           the input sample rate

       key This is 1 if the filtered frame is a key-frame, 0 otherwise.

       pos the position in the file of the filtered frame, -1 if the
           information is not available (e.g. for synthetic video)

       scene (video only)
           value between 0 and 1 to indicate a new scene; a low value reflects
           a low probability for the current frame to introduce a new scene,
           while a higher value means the current frame is more likely to be
           one (see the example below)

       concatdec_select
           The concat demuxer can select only part of a concat input file by
           setting an inpoint and an outpoint, but the output packets may not
           be entirely contained in the selected interval. By using this
           variable, it is possible to skip frames generated by the concat
           demuxer which are not exactly contained in the selected interval.

           This works by comparing the frame pts against the
           lavf.concat.start_time and the lavf.concat.duration packet metadata
           values which are also present in the decoded frames.

           The concatdec_select variable is -1 if the frame pts is at least
           start_time and either the duration metadata is missing or the frame
           pts is less than start_time + duration, 0 otherwise, and NaN if the
           start_time metadata is missing.

           That basically means that an input frame is selected if its pts is
           within the interval set by the concat demuxer.

       The default value of the select expression is "1".

       Examples

       o   Select all frames in input:

                   select

           The example above is the same as:

                   select=1

       o   Skip all frames:

                   select=0

       o   Select only I-frames:

                   select='eq(pict_type\,I)'

       o   Select one frame every 100:

                   select='not(mod(n\,100))'

       o   Select only frames contained in the 10-20 time interval:

                   select=between(t\,10\,20)

       o   Select only I-frames contained in the 10-20 time interval:

                   select=between(t\,10\,20)*eq(pict_type\,I)

       o   Select frames with a minimum distance of 10 seconds:

                   select='isnan(prev_selected_t)+gte(t-prev_selected_t\,10)'

       o   Use aselect to select only audio frames with samples number > 100:

                   aselect='gt(samples_n\,100)'

       o   Create a mosaic of the first scenes:

                   ffmpeg -i video.avi -vf select='gt(scene\,0.4)',scale=160:120,tile -frames:v 1 preview.png

           Comparing scene against a value between 0.3 and 0.5 is generally a
           sane choice.

       o   Send even and odd frames to separate outputs, and compose them:

                   select=n=2:e='mod(n, 2)+1' [odd][even]; [odd] pad=h=2*ih [tmp]; [tmp][even] overlay=y=h

       o   Select useful frames from an ffconcat file which is using inpoints
           and outpoints but where the source files are not intra frame only.

                   ffmpeg -copyts -vsync 0 -segment_time_metadata 1 -i input.ffconcat -vf select=concatdec_select -af aselect=concatdec_select output.avi

   sendcmd, asendcmd
       Send commands to filters in the filtergraph.

       These filters read commands to be sent to other filters in the
       filtergraph.

       "sendcmd" must be inserted between two video filters, "asendcmd" must
       be inserted between two audio filters, but apart from that they act the
       same way.

       The specification of commands can be provided in the filter arguments
       with the commands option, or in a file specified by the filename
       option.

       These filters accept the following options:

       commands, c
           Set the commands to be read and sent to the other filters.

       filename, f
           Set the filename of the commands to be read and sent to the other
           filters.

       Commands syntax

       A commands description consists of a sequence of interval
       specifications, comprising a list of commands to be executed when a
       particular event related to that interval occurs. The occurring event
       is typically the current frame time entering or leaving a given time
       interval.

       An interval is specified by the following syntax:

               <START>[-<END>] <COMMANDS>;

       The time interval is specified by the START and END times.  END is
       optional and defaults to the maximum time.

       The current frame time is considered within the specified interval if
       it is included in the interval [START, END), that is when the time is
       greater or equal to START and is lesser than END.

       COMMANDS consists of a sequence of one or more command specifications,
       separated by ",", relating to that interval.  The syntax of a command
       specification is given by:

               [<FLAGS>] <TARGET> <COMMAND> <ARG>

       FLAGS is optional and specifies the type of events relating to the time
       interval which enable sending the specified command, and must be a non-
       null sequence of identifier flags separated by "+" or "|" and enclosed
       between "[" and "]".

       The following flags are recognized:

       enter
           The command is sent when the current frame timestamp enters the
           specified interval. In other words, the command is sent when the
           previous frame timestamp was not in the given interval, and the
           current is.

       leave
           The command is sent when the current frame timestamp leaves the
           specified interval. In other words, the command is sent when the
           previous frame timestamp was in the given interval, and the current
           is not.

       expr
           The command ARG is interpreted as expression and result of
           expression is passed as ARG.

           The expression is evaluated through the eval API and can contain
           the following constants:

           POS Original position in the file of the frame, or undefined if
               undefined for the current frame.

           PTS The presentation timestamp in input.

           N   The count of the input frame for video or audio, starting from
               0.

           T   The time in seconds of the current frame.

           TS  The start time in seconds of the current command interval.

           TE  The end time in seconds of the current command interval.

           TI  The interpolated time of the current command interval, TI = (T
               - TS) / (TE - TS).

       If FLAGS is not specified, a default value of "[enter]" is assumed.

       TARGET specifies the target of the command, usually the name of the
       filter class or a specific filter instance name.

       COMMAND specifies the name of the command for the target filter.

       ARG is optional and specifies the optional list of argument for the
       given COMMAND.

       Between one interval specification and another, whitespaces, or
       sequences of characters starting with "#" until the end of line, are
       ignored and can be used to annotate comments.

       A simplified BNF description of the commands specification syntax
       follows:

               <COMMAND_FLAG>  ::= "enter" | "leave"
               <COMMAND_FLAGS> ::= <COMMAND_FLAG> [(+|"|")<COMMAND_FLAG>]
               <COMMAND>       ::= ["[" <COMMAND_FLAGS> "]"] <TARGET> <COMMAND> [<ARG>]
               <COMMANDS>      ::= <COMMAND> [,<COMMANDS>]
               <INTERVAL>      ::= <START>[-<END>] <COMMANDS>
               <INTERVALS>     ::= <INTERVAL>[;<INTERVALS>]

       Examples

       o   Specify audio tempo change at second 4:

                   asendcmd=c='4.0 atempo tempo 1.5',atempo

       o   Target a specific filter instance:

                   asendcmd=c='4.0 atempo@my tempo 1.5',atempo@my

       o   Specify a list of drawtext and hue commands in a file.

                   # show text in the interval 5-10
                   5.0-10.0 [enter] drawtext reinit 'fontfile=FreeSerif.ttf:text=hello world',
                            [leave] drawtext reinit 'fontfile=FreeSerif.ttf:text=';

                   # desaturate the image in the interval 15-20
                   15.0-20.0 [enter] hue s 0,
                             [enter] drawtext reinit 'fontfile=FreeSerif.ttf:text=nocolor',
                             [leave] hue s 1,
                             [leave] drawtext reinit 'fontfile=FreeSerif.ttf:text=color';

                   # apply an exponential saturation fade-out effect, starting from time 25
                   25 [enter] hue s exp(25-t)

           A filtergraph allowing to read and process the above command list
           stored in a file test.cmd, can be specified with:

                   sendcmd=f=test.cmd,drawtext=fontfile=FreeSerif.ttf:text='',hue

   setpts, asetpts
       Change the PTS (presentation timestamp) of the input frames.

       "setpts" works on video frames, "asetpts" on audio frames.

       This filter accepts the following options:

       expr
           The expression which is evaluated for each frame to construct its
           timestamp.

       The expression is evaluated through the eval API and can contain the
       following constants:

       FRAME_RATE, FR
           frame rate, only defined for constant frame-rate video

       PTS The presentation timestamp in input

       N   The count of the input frame for video or the number of consumed
           samples, not including the current frame for audio, starting from
           0.

       NB_CONSUMED_SAMPLES
           The number of consumed samples, not including the current frame
           (only audio)

       NB_SAMPLES, S
           The number of samples in the current frame (only audio)

       SAMPLE_RATE, SR
           The audio sample rate.

       STARTPTS
           The PTS of the first frame.

       STARTT
           the time in seconds of the first frame

       INTERLACED
           State whether the current frame is interlaced.

       T   the time in seconds of the current frame

       POS original position in the file of the frame, or undefined if
           undefined for the current frame

       PREV_INPTS
           The previous input PTS.

       PREV_INT
           previous input time in seconds

       PREV_OUTPTS
           The previous output PTS.

       PREV_OUTT
           previous output time in seconds

       RTCTIME
           The wallclock (RTC) time in microseconds. This is deprecated, use
           time(0) instead.

       RTCSTART
           The wallclock (RTC) time at the start of the movie in microseconds.

       TB  The timebase of the input timestamps.

       Examples

       o   Start counting PTS from zero

                   setpts=PTS-STARTPTS

       o   Apply fast motion effect:

                   setpts=0.5*PTS

       o   Apply slow motion effect:

                   setpts=2.0*PTS

       o   Set fixed rate of 25 frames per second:

                   setpts=N/(25*TB)

       o   Set fixed rate 25 fps with some jitter:

                   setpts='1/(25*TB) * (N + 0.05 * sin(N*2*PI/25))'

       o   Apply an offset of 10 seconds to the input PTS:

                   setpts=PTS+10/TB

       o   Generate timestamps from a "live source" and rebase onto the
           current timebase:

                   setpts='(RTCTIME - RTCSTART) / (TB * 1000000)'

       o   Generate timestamps by counting samples:

                   asetpts=N/SR/TB

   setrange
       Force color range for the output video frame.

       The "setrange" filter marks the color range property for the output
       frames. It does not change the input frame, but only sets the
       corresponding property, which affects how the frame is treated by
       following filters.

       The filter accepts the following options:

       range
           Available values are:

           auto
               Keep the same color range property.

           unspecified, unknown
               Set the color range as unspecified.

           limited, tv, mpeg
               Set the color range as limited.

           full, pc, jpeg
               Set the color range as full.

   settb, asettb
       Set the timebase to use for the output frames timestamps.  It is mainly
       useful for testing timebase configuration.

       It accepts the following parameters:

       expr, tb
           The expression which is evaluated into the output timebase.

       The value for tb is an arithmetic expression representing a rational.
       The expression can contain the constants "AVTB" (the default timebase),
       "intb" (the input timebase) and "sr" (the sample rate, audio only).
       Default value is "intb".

       Examples

       o   Set the timebase to 1/25:

                   settb=expr=1/25

       o   Set the timebase to 1/10:

                   settb=expr=0.1

       o   Set the timebase to 1001/1000:

                   settb=1+0.001

       o   Set the timebase to 2*intb:

                   settb=2*intb

       o   Set the default timebase value:

                   settb=AVTB

   showcqt
       Convert input audio to a video output representing frequency spectrum
       logarithmically using Brown-Puckette constant Q transform algorithm
       with direct frequency domain coefficient calculation (but the transform
       itself is not really constant Q, instead the Q factor is actually
       variable/clamped), with musical tone scale, from E0 to D#10.

       The filter accepts the following options:

       size, s
           Specify the video size for the output. It must be even. For the
           syntax of this option, check the "Video size" section in the
           ffmpeg-utils manual.  Default value is "1920x1080".

       fps, rate, r
           Set the output frame rate. Default value is 25.

       bar_h
           Set the bargraph height. It must be even. Default value is "-1"
           which computes the bargraph height automatically.

       axis_h
           Set the axis height. It must be even. Default value is "-1" which
           computes the axis height automatically.

       sono_h
           Set the sonogram height. It must be even. Default value is "-1"
           which computes the sonogram height automatically.

       fullhd
           Set the fullhd resolution. This option is deprecated, use size, s
           instead. Default value is 1.

       sono_v, volume
           Specify the sonogram volume expression. It can contain variables:

           bar_v
               the bar_v evaluated expression

           frequency, freq, f
               the frequency where it is evaluated

           timeclamp, tc
               the value of timeclamp option

           and functions:

           a_weighting(f)
               A-weighting of equal loudness

           b_weighting(f)
               B-weighting of equal loudness

           c_weighting(f)
               C-weighting of equal loudness.

           Default value is 16.

       bar_v, volume2
           Specify the bargraph volume expression. It can contain variables:

           sono_v
               the sono_v evaluated expression

           frequency, freq, f
               the frequency where it is evaluated

           timeclamp, tc
               the value of timeclamp option

           and functions:

           a_weighting(f)
               A-weighting of equal loudness

           b_weighting(f)
               B-weighting of equal loudness

           c_weighting(f)
               C-weighting of equal loudness.

           Default value is "sono_v".

       sono_g, gamma
           Specify the sonogram gamma. Lower gamma makes the spectrum more
           contrast, higher gamma makes the spectrum having more range.
           Default value is 3.  Acceptable range is "[1, 7]".

       bar_g, gamma2
           Specify the bargraph gamma. Default value is 1. Acceptable range is
           "[1, 7]".

       bar_t
           Specify the bargraph transparency level. Lower value makes the
           bargraph sharper.  Default value is 1. Acceptable range is "[0,
           1]".

       timeclamp, tc
           Specify the transform timeclamp. At low frequency, there is trade-
           off between accuracy in time domain and frequency domain. If
           timeclamp is lower, event in time domain is represented more
           accurately (such as fast bass drum), otherwise event in frequency
           domain is represented more accurately (such as bass guitar).
           Acceptable range is "[0.002, 1]". Default value is 0.17.

       attack
           Set attack time in seconds. The default is 0 (disabled). Otherwise,
           it limits future samples by applying asymmetric windowing in time
           domain, useful when low latency is required. Accepted range is "[0,
           1]".

       basefreq
           Specify the transform base frequency. Default value is
           20.01523126408007475, which is frequency 50 cents below E0.
           Acceptable range is "[10, 100000]".

       endfreq
           Specify the transform end frequency. Default value is
           20495.59681441799654, which is frequency 50 cents above D#10.
           Acceptable range is "[10, 100000]".

       coeffclamp
           This option is deprecated and ignored.

       tlength
           Specify the transform length in time domain. Use this option to
           control accuracy trade-off between time domain and frequency domain
           at every frequency sample.  It can contain variables:

           frequency, freq, f
               the frequency where it is evaluated

           timeclamp, tc
               the value of timeclamp option.

           Default value is "384*tc/(384+tc*f)".

       count
           Specify the transform count for every video frame. Default value is
           6.  Acceptable range is "[1, 30]".

       fcount
           Specify the transform count for every single pixel. Default value
           is 0, which makes it computed automatically. Acceptable range is
           "[0, 10]".

       fontfile
           Specify font file for use with freetype to draw the axis. If not
           specified, use embedded font. Note that drawing with font file or
           embedded font is not implemented with custom basefreq and endfreq,
           use axisfile option instead.

       font
           Specify fontconfig pattern. This has lower priority than fontfile.
           The ":" in the pattern may be replaced by "|" to avoid unnecessary
           escaping.

       fontcolor
           Specify font color expression. This is arithmetic expression that
           should return integer value 0xRRGGBB. It can contain variables:

           frequency, freq, f
               the frequency where it is evaluated

           timeclamp, tc
               the value of timeclamp option

           and functions:

           midi(f)
               midi number of frequency f, some midi numbers: E0(16), C1(24),
               C2(36), A4(69)

           r(x), g(x), b(x)
               red, green, and blue value of intensity x.

           Default value is "st(0, (midi(f)-59.5)/12); st(1,
           if(between(ld(0),0,1), 0.5-0.5*cos(2*PI*ld(0)), 0)); r(1-ld(1)) +
           b(ld(1))".

       axisfile
           Specify image file to draw the axis. This option override fontfile
           and fontcolor option.

       axis, text
           Enable/disable drawing text to the axis. If it is set to 0, drawing
           to the axis is disabled, ignoring fontfile and axisfile option.
           Default value is 1.

       csp Set colorspace. The accepted values are:

           unspecified
               Unspecified (default)

           bt709
               BT.709

           fcc FCC

           bt470bg
               BT.470BG or BT.601-6 625

           smpte170m
               SMPTE-170M or BT.601-6 525

           smpte240m
               SMPTE-240M

           bt2020ncl
               BT.2020 with non-constant luminance

       cscheme
           Set spectrogram color scheme. This is list of floating point values
           with format "left_r|left_g|left_b|right_r|right_g|right_b".  The
           default is "1|0.5|0|0|0.5|1".

       Examples

       o   Playing audio while showing the spectrum:

                   ffplay -f lavfi 'amovie=a.mp3, asplit [a][out1]; [a] showcqt [out0]'

       o   Same as above, but with frame rate 30 fps:

                   ffplay -f lavfi 'amovie=a.mp3, asplit [a][out1]; [a] showcqt=fps=30:count=5 [out0]'

       o   Playing at 1280x720:

                   ffplay -f lavfi 'amovie=a.mp3, asplit [a][out1]; [a] showcqt=s=1280x720:count=4 [out0]'

       o   Disable sonogram display:

                   sono_h=0

       o   A1 and its harmonics: A1, A2, (near)E3, A3:

                   ffplay -f lavfi 'aevalsrc=0.1*sin(2*PI*55*t)+0.1*sin(4*PI*55*t)+0.1*sin(6*PI*55*t)+0.1*sin(8*PI*55*t),
                                    asplit[a][out1]; [a] showcqt [out0]'

       o   Same as above, but with more accuracy in frequency domain:

                   ffplay -f lavfi 'aevalsrc=0.1*sin(2*PI*55*t)+0.1*sin(4*PI*55*t)+0.1*sin(6*PI*55*t)+0.1*sin(8*PI*55*t),
                                    asplit[a][out1]; [a] showcqt=timeclamp=0.5 [out0]'

       o   Custom volume:

                   bar_v=10:sono_v=bar_v*a_weighting(f)

       o   Custom gamma, now spectrum is linear to the amplitude.

                   bar_g=2:sono_g=2

       o   Custom tlength equation:

                   tc=0.33:tlength='st(0,0.17); 384*tc / (384 / ld(0) + tc*f /(1-ld(0))) + 384*tc / (tc*f / ld(0) + 384 /(1-ld(0)))'

       o   Custom fontcolor and fontfile, C-note is colored green, others are
           colored blue:

                   fontcolor='if(mod(floor(midi(f)+0.5),12), 0x0000FF, g(1))':fontfile=myfont.ttf

       o   Custom font using fontconfig:

                   font='Courier New,Monospace,mono|bold'

       o   Custom frequency range with custom axis using image file:

                   axisfile=myaxis.png:basefreq=40:endfreq=10000

   showfreqs
       Convert input audio to video output representing the audio power
       spectrum.  Audio amplitude is on Y-axis while frequency is on X-axis.

       The filter accepts the following options:

       size, s
           Specify size of video. For the syntax of this option, check the
           "Video size" section in the ffmpeg-utils manual.  Default is
           "1024x512".

       mode
           Set display mode.  This set how each frequency bin will be
           represented.

           It accepts the following values:

           line
           bar
           dot

           Default is "bar".

       ascale
           Set amplitude scale.

           It accepts the following values:

           lin Linear scale.

           sqrt
               Square root scale.

           cbrt
               Cubic root scale.

           log Logarithmic scale.

           Default is "log".

       fscale
           Set frequency scale.

           It accepts the following values:

           lin Linear scale.

           log Logarithmic scale.

           rlog
               Reverse logarithmic scale.

           Default is "lin".

       win_size
           Set window size. Allowed range is from 16 to 65536.

           Default is 2048

       win_func
           Set windowing function.

           It accepts the following values:

           rect
           bartlett
           hanning
           hamming
           blackman
           welch
           flattop
           bharris
           bnuttall
           bhann
           sine
           nuttall
           lanczos
           gauss
           tukey
           dolph
           cauchy
           parzen
           poisson
           bohman

           Default is "hanning".

       overlap
           Set window overlap. In range "[0, 1]". Default is 1, which means
           optimal overlap for selected window function will be picked.

       averaging
           Set time averaging. Setting this to 0 will display current maximal
           peaks.  Default is 1, which means time averaging is disabled.

       colors
           Specify list of colors separated by space or by '|' which will be
           used to draw channel frequencies. Unrecognized or missing colors
           will be replaced by white color.

       cmode
           Set channel display mode.

           It accepts the following values:

           combined
           separate

           Default is "combined".

       minamp
           Set minimum amplitude used in "log" amplitude scaler.

       data
           Set data display mode.

           It accepts the following values:

           magnitude
           phase
           delay

           Default is "magnitude".

   showspatial
       Convert stereo input audio to a video output, representing the spatial
       relationship between two channels.

       The filter accepts the following options:

       size, s
           Specify the video size for the output. For the syntax of this
           option, check the "Video size" section in the ffmpeg-utils manual.
           Default value is "512x512".

       win_size
           Set window size. Allowed range is from 1024 to 65536. Default size
           is 4096.

       win_func
           Set window function.

           It accepts the following values:

           rect
           bartlett
           hann
           hanning
           hamming
           blackman
           welch
           flattop
           bharris
           bnuttall
           bhann
           sine
           nuttall
           lanczos
           gauss
           tukey
           dolph
           cauchy
           parzen
           poisson
           bohman

           Default value is "hann".

       overlap
           Set ratio of overlap window. Default value is 0.5.  When value is 1
           overlap is set to recommended size for specific window function
           currently used.

   showspectrum
       Convert input audio to a video output, representing the audio frequency
       spectrum.

       The filter accepts the following options:

       size, s
           Specify the video size for the output. For the syntax of this
           option, check the "Video size" section in the ffmpeg-utils manual.
           Default value is "640x512".

       slide
           Specify how the spectrum should slide along the window.

           It accepts the following values:

           replace
               the samples start again on the left when they reach the right

           scroll
               the samples scroll from right to left

           fullframe
               frames are only produced when the samples reach the right

           rscroll
               the samples scroll from left to right

           Default value is "replace".

       mode
           Specify display mode.

           It accepts the following values:

           combined
               all channels are displayed in the same row

           separate
               all channels are displayed in separate rows

           Default value is combined.

       color
           Specify display color mode.

           It accepts the following values:

           channel
               each channel is displayed in a separate color

           intensity
               each channel is displayed using the same color scheme

           rainbow
               each channel is displayed using the rainbow color scheme

           moreland
               each channel is displayed using the moreland color scheme

           nebulae
               each channel is displayed using the nebulae color scheme

           fire
               each channel is displayed using the fire color scheme

           fiery
               each channel is displayed using the fiery color scheme

           fruit
               each channel is displayed using the fruit color scheme

           cool
               each channel is displayed using the cool color scheme

           magma
               each channel is displayed using the magma color scheme

           green
               each channel is displayed using the green color scheme

           viridis
               each channel is displayed using the viridis color scheme

           plasma
               each channel is displayed using the plasma color scheme

           cividis
               each channel is displayed using the cividis color scheme

           terrain
               each channel is displayed using the terrain color scheme

           Default value is channel.

       scale
           Specify scale used for calculating intensity color values.

           It accepts the following values:

           lin linear

           sqrt
               square root, default

           cbrt
               cubic root

           log logarithmic

           4thrt
               4th root

           5thrt
               5th root

           Default value is sqrt.

       fscale
           Specify frequency scale.

           It accepts the following values:

           lin linear

           log logarithmic

           Default value is lin.

       saturation
           Set saturation modifier for displayed colors. Negative values
           provide alternative color scheme. 0 is no saturation at all.
           Saturation must be in [-10.0, 10.0] range.  Default value is 1.

       win_func
           Set window function.

           It accepts the following values:

           rect
           bartlett
           hann
           hanning
           hamming
           blackman
           welch
           flattop
           bharris
           bnuttall
           bhann
           sine
           nuttall
           lanczos
           gauss
           tukey
           dolph
           cauchy
           parzen
           poisson
           bohman

           Default value is "hann".

       orientation
           Set orientation of time vs frequency axis. Can be "vertical" or
           "horizontal". Default is "vertical".

       overlap
           Set ratio of overlap window. Default value is 0.  When value is 1
           overlap is set to recommended size for specific window function
           currently used.

       gain
           Set scale gain for calculating intensity color values.  Default
           value is 1.

       data
           Set which data to display. Can be "magnitude", default or "phase".

       rotation
           Set color rotation, must be in [-1.0, 1.0] range.  Default value is
           0.

       start
           Set start frequency from which to display spectrogram. Default is
           0.

       stop
           Set stop frequency to which to display spectrogram. Default is 0.

       fps Set upper frame rate limit. Default is "auto", unlimited.

       legend
           Draw time and frequency axes and legends. Default is disabled.

       The usage is very similar to the showwaves filter; see the examples in
       that section.

       Examples

       o   Large window with logarithmic color scaling:

                   showspectrum=s=1280x480:scale=log

       o   Complete example for a colored and sliding spectrum per channel
           using ffplay:

                   ffplay -f lavfi 'amovie=input.mp3, asplit [a][out1];
                                [a] showspectrum=mode=separate:color=intensity:slide=1:scale=cbrt [out0]'

   showspectrumpic
       Convert input audio to a single video frame, representing the audio
       frequency spectrum.

       The filter accepts the following options:

       size, s
           Specify the video size for the output. For the syntax of this
           option, check the "Video size" section in the ffmpeg-utils manual.
           Default value is "4096x2048".

       mode
           Specify display mode.

           It accepts the following values:

           combined
               all channels are displayed in the same row

           separate
               all channels are displayed in separate rows

           Default value is combined.

       color
           Specify display color mode.

           It accepts the following values:

           channel
               each channel is displayed in a separate color

           intensity
               each channel is displayed using the same color scheme

           rainbow
               each channel is displayed using the rainbow color scheme

           moreland
               each channel is displayed using the moreland color scheme

           nebulae
               each channel is displayed using the nebulae color scheme

           fire
               each channel is displayed using the fire color scheme

           fiery
               each channel is displayed using the fiery color scheme

           fruit
               each channel is displayed using the fruit color scheme

           cool
               each channel is displayed using the cool color scheme

           magma
               each channel is displayed using the magma color scheme

           green
               each channel is displayed using the green color scheme

           viridis
               each channel is displayed using the viridis color scheme

           plasma
               each channel is displayed using the plasma color scheme

           cividis
               each channel is displayed using the cividis color scheme

           terrain
               each channel is displayed using the terrain color scheme

           Default value is intensity.

       scale
           Specify scale used for calculating intensity color values.

           It accepts the following values:

           lin linear

           sqrt
               square root, default

           cbrt
               cubic root

           log logarithmic

           4thrt
               4th root

           5thrt
               5th root

           Default value is log.

       fscale
           Specify frequency scale.

           It accepts the following values:

           lin linear

           log logarithmic

           Default value is lin.

       saturation
           Set saturation modifier for displayed colors. Negative values
           provide alternative color scheme. 0 is no saturation at all.
           Saturation must be in [-10.0, 10.0] range.  Default value is 1.

       win_func
           Set window function.

           It accepts the following values:

           rect
           bartlett
           hann
           hanning
           hamming
           blackman
           welch
           flattop
           bharris
           bnuttall
           bhann
           sine
           nuttall
           lanczos
           gauss
           tukey
           dolph
           cauchy
           parzen
           poisson
           bohman

           Default value is "hann".

       orientation
           Set orientation of time vs frequency axis. Can be "vertical" or
           "horizontal". Default is "vertical".

       gain
           Set scale gain for calculating intensity color values.  Default
           value is 1.

       legend
           Draw time and frequency axes and legends. Default is enabled.

       rotation
           Set color rotation, must be in [-1.0, 1.0] range.  Default value is
           0.

       start
           Set start frequency from which to display spectrogram. Default is
           0.

       stop
           Set stop frequency to which to display spectrogram. Default is 0.

       Examples

       o   Extract an audio spectrogram of a whole audio track in a 1024x1024
           picture using ffmpeg:

                   ffmpeg -i audio.flac -lavfi showspectrumpic=s=1024x1024 spectrogram.png

   showvolume
       Convert input audio volume to a video output.

       The filter accepts the following options:

       rate, r
           Set video rate.

       b   Set border width, allowed range is [0, 5]. Default is 1.

       w   Set channel width, allowed range is [80, 8192]. Default is 400.

       h   Set channel height, allowed range is [1, 900]. Default is 20.

       f   Set fade, allowed range is [0, 1]. Default is 0.95.

       c   Set volume color expression.

           The expression can use the following variables:

           VOLUME
               Current max volume of channel in dB.

           PEAK
               Current peak.

           CHANNEL
               Current channel number, starting from 0.

       t   If set, displays channel names. Default is enabled.

       v   If set, displays volume values. Default is enabled.

       o   Set orientation, can be horizontal: "h" or vertical: "v", default
           is "h".

       s   Set step size, allowed range is [0, 5]. Default is 0, which means
           step is disabled.

       p   Set background opacity, allowed range is [0, 1]. Default is 0.

       m   Set metering mode, can be peak: "p" or rms: "r", default is "p".

       ds  Set display scale, can be linear: "lin" or log: "log", default is
           "lin".

       dm  In second.  If set to > 0., display a line for the max level in the
           previous seconds.  default is disabled: 0.

       dmc The color of the max line. Use when "dm" option is set to > 0.
           default is: "orange"

   showwaves
       Convert input audio to a video output, representing the samples waves.

       The filter accepts the following options:

       size, s
           Specify the video size for the output. For the syntax of this
           option, check the "Video size" section in the ffmpeg-utils manual.
           Default value is "600x240".

       mode
           Set display mode.

           Available values are:

           point
               Draw a point for each sample.

           line
               Draw a vertical line for each sample.

           p2p Draw a point for each sample and a line between them.

           cline
               Draw a centered vertical line for each sample.

           Default value is "point".

       n   Set the number of samples which are printed on the same column. A
           larger value will decrease the frame rate. Must be a positive
           integer. This option can be set only if the value for rate is not
           explicitly specified.

       rate, r
           Set the (approximate) output frame rate. This is done by setting
           the option n. Default value is "25".

       split_channels
           Set if channels should be drawn separately or overlap. Default
           value is 0.

       colors
           Set colors separated by '|' which are going to be used for drawing
           of each channel.

       scale
           Set amplitude scale.

           Available values are:

           lin Linear.

           log Logarithmic.

           sqrt
               Square root.

           cbrt
               Cubic root.

           Default is linear.

       draw
           Set the draw mode. This is mostly useful to set for high n.

           Available values are:

           scale
               Scale pixel values for each drawn sample.

           full
               Draw every sample directly.

           Default value is "scale".

       Examples

       o   Output the input file audio and the corresponding video
           representation at the same time:

                   amovie=a.mp3,asplit[out0],showwaves[out1]

       o   Create a synthetic signal and show it with showwaves, forcing a
           frame rate of 30 frames per second:

                   aevalsrc=sin(1*2*PI*t)*sin(880*2*PI*t):cos(2*PI*200*t),asplit[out0],showwaves=r=30[out1]

   showwavespic
       Convert input audio to a single video frame, representing the samples
       waves.

       The filter accepts the following options:

       size, s
           Specify the video size for the output. For the syntax of this
           option, check the "Video size" section in the ffmpeg-utils manual.
           Default value is "600x240".

       split_channels
           Set if channels should be drawn separately or overlap. Default
           value is 0.

       colors
           Set colors separated by '|' which are going to be used for drawing
           of each channel.

       scale
           Set amplitude scale.

           Available values are:

           lin Linear.

           log Logarithmic.

           sqrt
               Square root.

           cbrt
               Cubic root.

           Default is linear.

       draw
           Set the draw mode.

           Available values are:

           scale
               Scale pixel values for each drawn sample.

           full
               Draw every sample directly.

           Default value is "scale".

       filter
           Set the filter mode.

           Available values are:

           average
               Use average samples values for each drawn sample.

           peak
               Use peak samples values for each drawn sample.

           Default value is "average".

       Examples

       o   Extract a channel split representation of the wave form of a whole
           audio track in a 1024x800 picture using ffmpeg:

                   ffmpeg -i audio.flac -lavfi showwavespic=split_channels=1:s=1024x800 waveform.png

   sidedata, asidedata
       Delete frame side data, or select frames based on it.

       This filter accepts the following options:

       mode
           Set mode of operation of the filter.

           Can be one of the following:

           select
               Select every frame with side data of "type".

           delete
               Delete side data of "type". If "type" is not set, delete all
               side data in the frame.

       type
           Set side data type used with all modes. Must be set for "select"
           mode. For the list of frame side data types, refer to the
           "AVFrameSideDataType" enum in libavutil/frame.h. For example, to
           choose "AV_FRAME_DATA_PANSCAN" side data, you must specify
           "PANSCAN".

   spectrumsynth
       Synthesize audio from 2 input video spectrums, first input stream
       represents magnitude across time and second represents phase across
       time.  The filter will transform from frequency domain as displayed in
       videos back to time domain as presented in audio output.

       This filter is primarily created for reversing processed showspectrum
       filter outputs, but can synthesize sound from other spectrograms too.
       But in such case results are going to be poor if the phase data is not
       available, because in such cases phase data need to be recreated,
       usually it's just recreated from random noise.  For best results use
       gray only output ("channel" color mode in showspectrum filter) and
       "log" scale for magnitude video and "lin" scale for phase video. To
       produce phase, for 2nd video, use "data" option. Inputs videos should
       generally use "fullframe" slide mode as that saves resources needed for
       decoding video.

       The filter accepts the following options:

       sample_rate
           Specify sample rate of output audio, the sample rate of audio from
           which spectrum was generated may differ.

       channels
           Set number of channels represented in input video spectrums.

       scale
           Set scale which was used when generating magnitude input spectrum.
           Can be "lin" or "log". Default is "log".

       slide
           Set slide which was used when generating inputs spectrums.  Can be
           "replace", "scroll", "fullframe" or "rscroll".  Default is
           "fullframe".

       win_func
           Set window function used for resynthesis.

       overlap
           Set window overlap. In range "[0, 1]". Default is 1, which means
           optimal overlap for selected window function will be picked.

       orientation
           Set orientation of input videos. Can be "vertical" or "horizontal".
           Default is "vertical".

       Examples

       o   First create magnitude and phase videos from audio, assuming audio
           is stereo with 44100 sample rate, then resynthesize videos back to
           audio with spectrumsynth:

                   ffmpeg -i input.flac -lavfi showspectrum=mode=separate:scale=log:overlap=0.875:color=channel:slide=fullframe:data=magnitude -an -c:v rawvideo magnitude.nut
                   ffmpeg -i input.flac -lavfi showspectrum=mode=separate:scale=lin:overlap=0.875:color=channel:slide=fullframe:data=phase -an -c:v rawvideo phase.nut
                   ffmpeg -i magnitude.nut -i phase.nut -lavfi spectrumsynth=channels=2:sample_rate=44100:win_func=hann:overlap=0.875:slide=fullframe output.flac

   split, asplit
       Split input into several identical outputs.

       "asplit" works with audio input, "split" with video.

       The filter accepts a single parameter which specifies the number of
       outputs. If unspecified, it defaults to 2.

       Examples

       o   Create two separate outputs from the same input:

                   [in] split [out0][out1]

       o   To create 3 or more outputs, you need to specify the number of
           outputs, like in:

                   [in] asplit=3 [out0][out1][out2]

       o   Create two separate outputs from the same input, one cropped and
           one padded:

                   [in] split [splitout1][splitout2];
                   [splitout1] crop=100:100:0:0    [cropout];
                   [splitout2] pad=200:200:100:100 [padout];

       o   Create 5 copies of the input audio with ffmpeg:

                   ffmpeg -i INPUT -filter_complex asplit=5 OUTPUT

   zmq, azmq
       Receive commands sent through a libzmq client, and forward them to
       filters in the filtergraph.

       "zmq" and "azmq" work as a pass-through filters. "zmq" must be inserted
       between two video filters, "azmq" between two audio filters. Both are
       capable to send messages to any filter type.

       To enable these filters you need to install the libzmq library and
       headers and configure FFmpeg with "--enable-libzmq".

       For more information about libzmq see: <http://www.zeromq.org/>

       The "zmq" and "azmq" filters work as a libzmq server, which receives
       messages sent through a network interface defined by the bind_address
       (or the abbreviation "b") option.  Default value of this option is
       tcp://localhost:5555. You may want to alter this value to your needs,
       but do not forget to escape any ':' signs (see filtergraph escaping).

       The received message must be in the form:

               <TARGET> <COMMAND> [<ARG>]

       TARGET specifies the target of the command, usually the name of the
       filter class or a specific filter instance name. The default filter
       instance name uses the pattern Parsed_<filter_name>_<index>, but you
       can override this by using the filter_name@id syntax (see Filtergraph
       syntax).

       COMMAND specifies the name of the command for the target filter.

       ARG is optional and specifies the optional argument list for the given
       COMMAND.

       Upon reception, the message is processed and the corresponding command
       is injected into the filtergraph. Depending on the result, the filter
       will send a reply to the client, adopting the format:

               <ERROR_CODE> <ERROR_REASON>
               <MESSAGE>

       MESSAGE is optional.

       Examples

       Look at tools/zmqsend for an example of a zmq client which can be used
       to send commands processed by these filters.

       Consider the following filtergraph generated by ffplay.  In this
       example the last overlay filter has an instance name. All other filters
       will have default instance names.

               ffplay -dumpgraph 1 -f lavfi "
               color=s=100x100:c=red  [l];
               color=s=100x100:c=blue [r];
               nullsrc=s=200x100, zmq [bg];
               [bg][l]   overlay     [bg+l];
               [bg+l][r] overlay@my=x=100 "

       To change the color of the left side of the video, the following
       command can be used:

               echo Parsed_color_0 c yellow | tools/zmqsend

       To change the right side:

               echo Parsed_color_1 c pink | tools/zmqsend

       To change the position of the right side:

               echo overlay@my x 150 | tools/zmqsend


MULTIMEDIA SOURCES

       Below is a description of the currently available multimedia sources.

   amovie
       This is the same as movie source, except it selects an audio stream by
       default.

   movie
       Read audio and/or video stream(s) from a movie container.

       It accepts the following parameters:

       filename
           The name of the resource to read (not necessarily a file; it can
           also be a device or a stream accessed through some protocol).

       format_name, f
           Specifies the format assumed for the movie to read, and can be
           either the name of a container or an input device. If not
           specified, the format is guessed from movie_name or by probing.

       seek_point, sp
           Specifies the seek point in seconds. The frames will be output
           starting from this seek point. The parameter is evaluated with
           "av_strtod", so the numerical value may be suffixed by an IS
           postfix. The default value is "0".

       streams, s
           Specifies the streams to read. Several streams can be specified,
           separated by "+". The source will then have as many outputs, in the
           same order. The syntax is explained in the "Stream specifiers"
           section in the ffmpeg manual. Two special names, "dv" and "da"
           specify respectively the default (best suited) video and audio
           stream. Default is "dv", or "da" if the filter is called as
           "amovie".

       stream_index, si
           Specifies the index of the video stream to read. If the value is
           -1, the most suitable video stream will be automatically selected.
           The default value is "-1". Deprecated. If the filter is called
           "amovie", it will select audio instead of video.

       loop
           Specifies how many times to read the stream in sequence.  If the
           value is 0, the stream will be looped infinitely.  Default value is
           "1".

           Note that when the movie is looped the source timestamps are not
           changed, so it will generate non monotonically increasing
           timestamps.

       discontinuity
           Specifies the time difference between frames above which the point
           is considered a timestamp discontinuity which is removed by
           adjusting the later timestamps.

       It allows overlaying a second video on top of the main input of a
       filtergraph, as shown in this graph:

               input -----------> deltapts0 --> overlay --> output
                                                   ^
                                                   |
               movie --> scale--> deltapts1 -------+

       Examples

       o   Skip 3.2 seconds from the start of the AVI file in.avi, and overlay
           it on top of the input labelled "in":

                   movie=in.avi:seek_point=3.2, scale=180:-1, setpts=PTS-STARTPTS [over];
                   [in] setpts=PTS-STARTPTS [main];
                   [main][over] overlay=16:16 [out]

       o   Read from a video4linux2 device, and overlay it on top of the input
           labelled "in":

                   movie=/dev/video0:f=video4linux2, scale=180:-1, setpts=PTS-STARTPTS [over];
                   [in] setpts=PTS-STARTPTS [main];
                   [main][over] overlay=16:16 [out]

       o   Read the first video stream and the audio stream with id 0x81 from
           dvd.vob; the video is connected to the pad named "video" and the
           audio is connected to the pad named "audio":

                   movie=dvd.vob:s=v:0+#0x81 [video] [audio]

       Commands

       Both movie and amovie support the following commands:

       seek
           Perform seek using "av_seek_frame".  The syntax is: seek
           stream_index|timestamp|flags

           o   stream_index: If stream_index is -1, a default stream is
               selected, and timestamp is automatically converted from
               AV_TIME_BASE units to the stream specific time_base.

           o   timestamp: Timestamp in AVStream.time_base units or, if no
               stream is specified, in AV_TIME_BASE units.

           o   flags: Flags which select direction and seeking mode.

       get_duration
           Get movie duration in AV_TIME_BASE units.


SEE ALSO

       ffmpeg(1), ffplay(1), ffprobe(1), libavfilter(3)


AUTHORS

       The FFmpeg developers.

       For details about the authorship, see the Git history of the project
       (git://source.ffmpeg.org/ffmpeg), e.g. by typing the command git log in
       the FFmpeg source directory, or browsing the online repository at
       <http://source.ffmpeg.org>.

       Maintainers for the specific components are listed in the file
       MAINTAINERS in the source code tree.



                                                             ffmpeg-filters(1)

ffmpeg 4.4 - Generated Fri Apr 23 07:50:23 CDT 2021
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