AVDISCARD_NONE    322 fftools/ffmpeg_filter.c     ist->st->discard = AVDISCARD_NONE;
AVDISCARD_NONE    815 fftools/ffmpeg_opt.c         ist->user_set_discard = AVDISCARD_NONE;
AVDISCARD_NONE    307 libavcodec/options_table.h {"none"            , "discard no frame",                    0, AV_OPT_TYPE_CONST, {.i64 = AVDISCARD_NONE    }, INT_MIN, INT_MAX, V|D, "avdiscard"},
AVDISCARD_NONE   4634 libavformat/utils.c         program->discard = AVDISCARD_NONE;