AV_SYNC_EXTERNAL_CLOCK 1451 ffplay.c                   return AV_SYNC_EXTERNAL_CLOCK;
AV_SYNC_EXTERNAL_CLOCK 1453 ffplay.c               return AV_SYNC_EXTERNAL_CLOCK;
AV_SYNC_EXTERNAL_CLOCK 1588 ffplay.c           if (!is->paused && get_master_sync_type(is) == AV_SYNC_EXTERNAL_CLOCK && is->realtime)
AV_SYNC_EXTERNAL_CLOCK 3611 ffplay.c               av_sync_type = AV_SYNC_EXTERNAL_CLOCK;