AV_PERM_WRITE     224 libavfilter/buffersrc.c                                  (buf->perms & AV_PERM_WRITE) ? 0 : AV_BUFFER_FLAG_READONLY);
AV_PERM_WRITE     243 libavfilter/buffersrc.c                                dummy_ref, (buf->perms & AV_PERM_WRITE) ? 0 : AV_BUFFER_FLAG_READONLY);                           \