AV_PERM_READ      114 libavfilter/audio.c     samplesref->perms = perms | AV_PERM_READ;
AV_PERM_READ      301 libavfilter/buffersink.c                                                         AV_PERM_READ,
AV_PERM_READ      306 libavfilter/buffersink.c                                                         frame->linesize[0], AV_PERM_READ,
AV_PERM_READ       82 libavfilter/video.c     picref->perms = perms | AV_PERM_READ;