AV_CH_LAYOUT_5POINT1_BACK  103 3rdparty/include/ffmpeg_/libavutil/channel_layout.h #define AV_CH_LAYOUT_6POINT1_BACK      (AV_CH_LAYOUT_5POINT1_BACK|AV_CH_BACK_CENTER)
AV_CH_LAYOUT_5POINT1_BACK  109 3rdparty/include/ffmpeg_/libavutil/channel_layout.h #define AV_CH_LAYOUT_7POINT1_WIDE_BACK (AV_CH_LAYOUT_5POINT1_BACK|AV_CH_FRONT_LEFT_OF_CENTER|AV_CH_FRONT_RIGHT_OF_CENTER)