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GstStreamVolume

GstStreamVolume — Interface for elements that provide a stream volume

Properties

gboolean mute Read / Write
gdouble volume Read / Write

Types and Values

Object Hierarchy

    GInterface
    ╰── GstStreamVolume

Prerequisites

GstStreamVolume requires GObject.

Includes

#include <gst/audio/streamvolume.h>

Description

This interface is implemented by elements that provide a stream volume. Examples for such elements are volume and playbin.

Applications can use this interface to get or set the current stream volume. For this the "volume" GObject property can be used or the helper functions gst_stream_volume_set_volume() and gst_stream_volume_get_volume(). This volume is always a linear factor, i.e. 0.0 is muted 1.0 is 100%. For showing the volume in a GUI it might make sense to convert it to a different format by using gst_stream_volume_convert_volume(). Volume sliders should usually use a cubic volume.

Separate from the volume the stream can also be muted by the "mute" GObject property or gst_stream_volume_set_mute() and gst_stream_volume_get_mute().

Elements that provide some kind of stream volume should implement the "volume" and "mute" GObject properties and handle setting and getting of them properly. The volume property is defined to be a linear volume factor.

Functions

gst_stream_volume_get_volume ()

gdouble
gst_stream_volume_get_volume (GstStreamVolume *volume,
                              GstStreamVolumeFormat format);

Parameters

volume

GstStreamVolume that should be used

 

format

GstStreamVolumeFormat which should be returned

 

Returns

The current stream volume as linear factor


gst_stream_volume_set_volume ()

void
gst_stream_volume_set_volume (GstStreamVolume *volume,
                              GstStreamVolumeFormat format,
                              gdouble val);

Parameters

volume

GstStreamVolume that should be used

 

format

GstStreamVolumeFormat of val

 

val

Linear volume factor that should be set

 

gst_stream_volume_get_mute ()

gboolean
gst_stream_volume_get_mute (GstStreamVolume *volume);

Parameters

volume

GstStreamVolume that should be used

 

Returns

Returns TRUE if the stream is muted


gst_stream_volume_set_mute ()

void
gst_stream_volume_set_mute (GstStreamVolume *volume,
                            gboolean mute);

Parameters

volume

GstStreamVolume that should be used

 

mute

Mute state that should be set

 

gst_stream_volume_convert_volume ()

gdouble
gst_stream_volume_convert_volume (GstStreamVolumeFormat from,
                                  GstStreamVolumeFormat to,
                                  gdouble val);

Parameters

from

GstStreamVolumeFormat to convert from

 

to

GstStreamVolumeFormat to convert to

 

val

Volume in from format that should be converted

 

Returns

the converted volume

Types and Values

GstStreamVolume

typedef struct _GstStreamVolume GstStreamVolume;

enum GstStreamVolumeFormat

Different representations of a stream volume. gst_stream_volume_convert_volume() allows to convert between the different representations.

Formulas to convert from a linear to a cubic or dB volume are cbrt(val) and 20 * log10 (val).

Members

GST_STREAM_VOLUME_FORMAT_LINEAR

Linear scale factor, 1.0 = 100%

 

GST_STREAM_VOLUME_FORMAT_CUBIC

Cubic volume scale

 

GST_STREAM_VOLUME_FORMAT_DB

Logarithmic volume scale (dB, amplitude not power)

 

Property Details

The “mute” property

  “mute”                     gboolean

Mute the audio channel without changing the volume.

Flags: Read / Write

Default value: FALSE


The “volume” property

  “volume”                   gdouble

Linear volume factor, 1.0=100%.

Flags: Read / Write

Allowed values: >= 0

Default value: 1

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