Configuration

Data processing

Shutdown phase

Subclass is responsible for providing pad template caps for source and sink pads. The pads need to be named "sink" and "src". It should also be able to provide fixed src pad caps in getcaps by the time it calls gst_video_encoder_finish_frame .

Things that subclass need to take care of:

The “qos” property will enable the Quality-of-Service features of the encoder which gather statistics about the real-time performance of the downstream elements. If enabled, subclasses can use gst_video_encoder_get_max_encode_time() to check if input frames are already late and drop them right away to give a chance to the pipeline to catch up.

GST_VIDEO_ENCODER_CAST()

#define GST_VIDEO_ENCODER_CAST(enc) ((GstVideoEncoder*)enc)

GST_VIDEO_ENCODER_SINK_PAD()

#define GST_VIDEO_ENCODER_SINK_PAD(obj)        (((GstVideoEncoder *) (obj))->sinkpad)

Gives the pointer to the sink GstPad object of the element.

GST_VIDEO_ENCODER_SRC_PAD()

#define GST_VIDEO_ENCODER_SRC_PAD(obj)         (((GstVideoEncoder *) (obj))->srcpad)

Gives the pointer to the source GstPad object of the element.

GST_VIDEO_ENCODER_INPUT_SEGMENT()

#define GST_VIDEO_ENCODER_INPUT_SEGMENT(obj)     (GST_VIDEO_ENCODER_CAST (obj)->input_segment)

Gives the segment of the element.

GST_VIDEO_ENCODER_OUTPUT_SEGMENT()

#define GST_VIDEO_ENCODER_OUTPUT_SEGMENT(obj)     (GST_VIDEO_ENCODER_CAST (obj)->output_segment)

Gives the segment of the element.

GST_VIDEO_ENCODER_STREAM_LOCK()

#define GST_VIDEO_ENCODER_STREAM_LOCK(encoder) g_rec_mutex_lock (&GST_VIDEO_ENCODER (encoder)->stream_lock)

Obtain a lock to protect the encoder function from concurrent access.

GST_VIDEO_ENCODER_STREAM_UNLOCK()

#define GST_VIDEO_ENCODER_STREAM_UNLOCK(encoder) g_rec_mutex_unlock (&GST_VIDEO_ENCODER (encoder)->stream_lock)

Release the lock that protects the encoder function from concurrent access.

gst_video_encoder_allocate_output_buffer ()

GstBuffer *
gst_video_encoder_allocate_output_buffer
                               (GstVideoEncoder *encoder,
                                gsize size);

Helper function that allocates a buffer to hold an encoded video frame for encoder 's current GstVideoCodecState.

gst_video_encoder_allocate_output_frame ()

GstFlowReturn
gst_video_encoder_allocate_output_frame
                               (GstVideoEncoder *encoder,
                                GstVideoCodecFrame *frame,
                                gsize size);

Helper function that allocates a buffer to hold an encoded video frame for encoder 's current GstVideoCodecState. Subclass should already have configured video state and set src pad caps.

The buffer allocated here is owned by the frame and you should only keep references to the frame, not the buffer.

gst_video_encoder_get_allocator ()

void
gst_video_encoder_get_allocator (GstVideoEncoder *encoder,
                                 GstAllocator **allocator,
                                 GstAllocationParams *params);

Lets GstVideoEncoder sub-classes to know the memory allocator used by the base class and its params .

Unref the allocator after use it.

gst_video_encoder_finish_frame ()

GstFlowReturn
gst_video_encoder_finish_frame (GstVideoEncoder *encoder,
                                GstVideoCodecFrame *frame);

frame must have a valid encoded data buffer, whose metadata fields are then appropriately set according to frame data or no buffer at all if the frame should be dropped. It is subsequently pushed downstream or provided to pre_push . In any case, the frame is considered finished and released.

After calling this function the output buffer of the frame is to be considered read-only. This function will also change the metadata of the buffer.

gst_video_encoder_negotiate ()

gboolean
gst_video_encoder_negotiate (GstVideoEncoder *encoder);

Negotiate with downstream elements to currently configured GstVideoCodecState. Unmark GST_PAD_FLAG_NEED_RECONFIGURE in any case. But mark it again if negotiate fails.

gst_video_encoder_get_frame ()

GstVideoCodecFrame *
gst_video_encoder_get_frame (GstVideoEncoder *encoder,
                             int frame_number);

Get a pending unfinished GstVideoCodecFrame

gst_video_encoder_get_frames ()

GList *
gst_video_encoder_get_frames (GstVideoEncoder *encoder);

Get all pending unfinished GstVideoCodecFrame

gst_video_encoder_get_oldest_frame ()

GstVideoCodecFrame *
gst_video_encoder_get_oldest_frame (GstVideoEncoder *encoder);

Get the oldest unfinished pending GstVideoCodecFrame

gst_video_encoder_set_headers ()

void
gst_video_encoder_set_headers (GstVideoEncoder *encoder,
                               GList *headers);

Set the codec headers to be sent downstream whenever requested.

gst_video_encoder_get_latency ()

void
gst_video_encoder_get_latency (GstVideoEncoder *encoder,
                               GstClockTime *min_latency,
                               GstClockTime *max_latency);

Query the configured encoding latency. Results will be returned via min_latency and max_latency .

gst_video_encoder_set_latency ()

void
gst_video_encoder_set_latency (GstVideoEncoder *encoder,
                               GstClockTime min_latency,
                               GstClockTime max_latency);

Informs baseclass of encoding latency.

gst_video_encoder_set_output_state ()

GstVideoCodecState *
gst_video_encoder_set_output_state (GstVideoEncoder *encoder,
                                    GstCaps *caps,
                                    GstVideoCodecState *reference);

Creates a new GstVideoCodecState with the specified caps as the output state for the encoder. Any previously set output state on encoder will be replaced by the newly created one.

The specified caps should not contain any resolution, pixel-aspect-ratio, framerate, codec-data, .... Those should be specified instead in the returned GstVideoCodecState.

If the subclass wishes to copy over existing fields (like pixel aspect ratio, or framerate) from an existing GstVideoCodecState, it can be provided as a reference .

If the subclass wishes to override some fields from the output state (like pixel-aspect-ratio or framerate) it can do so on the returned GstVideoCodecState.

The new output state will only take effect (set on pads and buffers) starting from the next call to gst_video_encoder_finish_frame().

gst_video_encoder_get_output_state ()

GstVideoCodecState *
gst_video_encoder_get_output_state (GstVideoEncoder *encoder);

Get the current GstVideoCodecState

gst_video_encoder_set_min_pts ()

void
gst_video_encoder_set_min_pts (GstVideoEncoder *encoder,
                               GstClockTime min_pts);

Request minimal value for PTS passed to handle_frame.

For streams with reordered frames this can be used to ensure that there is enough time to accomodate first DTS, which may be less than first PTS

Since 1.6

gst_video_encoder_proxy_getcaps ()

GstCaps *
gst_video_encoder_proxy_getcaps (GstVideoEncoder *enc,
                                 GstCaps *caps,
                                 GstCaps *filter);

Returns caps that express caps (or sink template caps if caps == NULL) restricted to resolution/format/... combinations supported by downstream elements (e.g. muxers).

gst_video_encoder_merge_tags ()

void
gst_video_encoder_merge_tags (GstVideoEncoder *encoder,
                              const GstTagList *tags,
                              GstTagMergeMode mode);

Sets the video encoder tags and how they should be merged with any upstream stream tags. This will override any tags previously-set with gst_video_encoder_merge_tags().

Note that this is provided for convenience, and the subclass is not required to use this and can still do tag handling on its own.

MT safe.

gst_video_encoder_get_max_encode_time ()

GstClockTimeDiff
gst_video_encoder_get_max_encode_time (GstVideoEncoder *encoder,
                                       GstVideoCodecFrame *frame);

Determines maximum possible encoding time for frame that will allow it to encode and arrive in time (as determined by QoS events). In particular, a negative result means encoding in time is no longer possible and should therefore occur as soon/skippy as possible.

If no QoS events have been received from downstream, or if “qos” is disabled this function returns G_MAXINT64.

Since: 1.14

GST_VIDEO_ENCODER_FLOW_DROPPED

#define GST_VIDEO_ENCODER_FLOW_DROPPED GST_FLOW_CUSTOM_SUCCESS_1

Returned when the event/buffer should be dropped.

GST_VIDEO_ENCODER_FLOW_NEED_DATA

#define GST_VIDEO_ENCODER_FLOW_NEED_DATA GST_FLOW_CUSTOM_SUCCESS

Returned while parsing to indicate more data is needed.

GST_VIDEO_ENCODER_SINK_NAME

#define GST_VIDEO_ENCODER_SINK_NAME    "sink"

The name of the templates for the sink pad.

GST_VIDEO_ENCODER_SRC_NAME

#define GST_VIDEO_ENCODER_SRC_NAME     "src"

The name of the templates for the source pad.

struct GstVideoEncoder

struct GstVideoEncoder {
};

The opaque GstVideoEncoder data structure.

struct GstVideoEncoderClass

struct GstVideoEncoderClass {
  /* virtual methods for subclasses */
  gboolean      (*open)         (GstVideoEncoder *encoder);

  gboolean      (*close)        (GstVideoEncoder *encoder);

  gboolean      (*start)        (GstVideoEncoder *encoder);

  gboolean      (*stop)         (GstVideoEncoder *encoder);

  gboolean      (*set_format)   (GstVideoEncoder *encoder,
				 GstVideoCodecState *state);

  GstFlowReturn (*handle_frame) (GstVideoEncoder *encoder,
				 GstVideoCodecFrame *frame);

  gboolean      (*reset)        (GstVideoEncoder *encoder,
				 gboolean hard);

  GstFlowReturn (*finish)       (GstVideoEncoder *encoder);

  GstFlowReturn (*pre_push)     (GstVideoEncoder *encoder,
				 GstVideoCodecFrame *frame);

  GstCaps *     (*getcaps)      (GstVideoEncoder *enc,
                                 GstCaps *filter);

  gboolean      (*sink_event)   (GstVideoEncoder *encoder,
				 GstEvent *event);

  gboolean      (*src_event)    (GstVideoEncoder *encoder,
				 GstEvent *event);

  gboolean      (*negotiate)    (GstVideoEncoder *encoder);

  gboolean      (*decide_allocation)  (GstVideoEncoder *encoder, GstQuery *query);

  gboolean      (*propose_allocation) (GstVideoEncoder * encoder,
                                       GstQuery * query);
  gboolean      (*flush)              (GstVideoEncoder *encoder);

  gboolean      (*sink_query)     (GstVideoEncoder *encoder,
				   GstQuery *query);

  gboolean      (*src_query)      (GstVideoEncoder *encoder,
				   GstQuery *query);

  gboolean      (*transform_meta) (GstVideoEncoder *encoder,
                                   GstVideoCodecFrame *frame,
                                   GstMeta * meta);
};

Subclasses can override any of the available virtual methods or not, as needed. At minimum handle_frame needs to be overridden, and set_format and get_caps are likely needed as well.