Function gstreamer_audio_sys::gst_buffer_add_audio_downmix_meta

pub unsafe extern "C" fn gst_buffer_add_audio_downmix_meta(
    buffer: *mut GstBuffer, 
    from_position: *const GstAudioChannelPosition, 
    from_channels: c_int, 
    to_position: *const GstAudioChannelPosition, 
    to_channels: c_int, 
    matrix: *mut *const c_float
) -> *mut GstAudioDownmixMeta