remove exceptions from FFV1 version 4?

[dericed]

The ffv1 spec currently lists a few exceptions:

https://github.com/FFmpeg/FFV1/blob/master/ffv1.md#rgb-exception
https://github.com/FFmpeg/FFV1/blob/master/ffv1.md#exception

Should these be removed in ffv1 version 4?

[JeromeMartinez]

In my opinion they should be removed in order to have a clean and less complex code managing theses parts.
If it leads to worse compression ratio, well, it may mean that we have a more global optimization to do somewhere (IIRC FFmpeg code has already some stuff in v4 for a global version of the RGB exception not yet in the spec draft).