gst_buffer_add_audio_downmix_meta ()

GstAudioDownmixMeta *
gst_buffer_add_audio_downmix_meta (GstBuffer *buffer,
                                   const GstAudioChannelPosition *from_position,
                                   gint from_channels,
                                   const GstAudioChannelPosition *to_position,
                                   gint to_channels,
                                   const gfloat **matrix);

Attaches GstAudioDownmixMeta metadata to buffer with the given parameters.

matrix is an two-dimensional array of to_channels times from_channels coefficients, i.e. the i-th output channels is constructed by multiplicating the input channels with the coefficients in matrix [i] and taking the sum of the results.

gst_buffer_get_audio_downmix_meta()

#define gst_buffer_get_audio_downmix_meta(b) ((GstAudioDownmixMeta*)gst_buffer_get_meta((b),GST_AUDIO_DOWNMIX_META_INFO))

gst_buffer_get_audio_downmix_meta_for_channels ()

GstAudioDownmixMeta *
gst_buffer_get_audio_downmix_meta_for_channels
                               (GstBuffer *buffer,
                                const GstAudioChannelPosition *to_position,
                                gint to_channels);

Find the GstAudioDownmixMeta on buffer for the given destination channel positions.

struct GstAudioDownmixMeta

struct GstAudioDownmixMeta {
  GstMeta      meta;

  GstAudioChannelPosition *from_position;
  GstAudioChannelPosition *to_position;
  gint        from_channels, to_channels;
  gfloat       **matrix;
};

Extra buffer metadata describing audio downmixing matrix. This metadata is attached to audio buffers and contains a matrix to downmix the buffer number of channels to channels .

matrix is an two-dimensional array of to_channels times from_channels coefficients, i.e. the i-th output channels is constructed by multiplicating the input channels with the coefficients in matrix [i] and taking the sum of the results.