This interface is implemented by elements that provide a stream volume. Examples for such elements are volume and playbin2.

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.

GstStreamVolume

typedef struct _GstStreamVolume GstStreamVolume;

enum GstStreamVolumeFormat

typedef enum {
  GST_STREAM_VOLUME_FORMAT_LINEAR = 0,
  GST_STREAM_VOLUME_FORMAT_CUBIC,
  GST_STREAM_VOLUME_FORMAT_DB
} GstStreamVolumeFormat;

Different representations of a stream volume. gst_stream_volume_convert() 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).

Since 0.10.25

gst_stream_volume_get_volume ()

gdouble             gst_stream_volume_get_volume        (GstStreamVolume *volume,
                                                         GstStreamVolumeFormat format);

Since 0.10.25

gst_stream_volume_set_volume ()

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

Since 0.10.25

gst_stream_volume_get_mute ()

gboolean            gst_stream_volume_get_mute          (GstStreamVolume *volume);

Since 0.10.25

gst_stream_volume_set_mute ()

void                gst_stream_volume_set_mute          (GstStreamVolume *volume,
                                                         gboolean mute);

Since 0.10.25

gst_stream_volume_convert_volume ()

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

Since 0.10.25

The "mute" property

  "mute"                     gboolean              : Read / Write

Mute the audio channel without changing the volume.

Default value: FALSE

The "volume" property

  "volume"                   gdouble               : Read / Write

Linear volume factor, 1.0=100%.

Allowed values: >= 0

Default value: 1