CH_DIRECT_PAIR    929 libavfilter/avfiltergraph.c     { CH_SIDE_PAIR,       CH_DIRECT_PAIR     },
CH_DIRECT_PAIR    932 libavfilter/avfiltergraph.c     { CH_BACK_PAIR,       CH_DIRECT_PAIR     },
CH_DIRECT_PAIR    936 libavfilter/avfiltergraph.c     { AV_CH_BACK_CENTER,  CH_DIRECT_PAIR     },