Missing some cases that I could not test.
Also ffmpeg/chroma.c is locked, so I can but leave it broken.
Fix is for the remaining modules is obvious and the issue is easy to detect.
This allows transcoding say, DVD or DVB subs to normal ones.
Only tested with RTP output, but might also work with ogg, mp4, ts...
The problem is that most of these do not seem to check the encoding.