AV_CH_FRONT_CENTER 85 3rdparty/include/ffmpeg_/libavutil/channel_layout.h #define AV_CH_LAYOUT_MONO (AV_CH_FRONT_CENTER) AV_CH_FRONT_CENTER 89 3rdparty/include/ffmpeg_/libavutil/channel_layout.h #define AV_CH_LAYOUT_SURROUND (AV_CH_LAYOUT_STEREO|AV_CH_FRONT_CENTER)