EDIT: Got confused myself with the commits, ignore the content of my comment from before this edit.
- The main branch still has the needed code: https://github.com/uvjustin/PyAV/blob/57f2d39d1d7b44ac92abe3ddb6c5267c84fe5767/include/libavcodec/avcodec.pxd
- The v10.1.1 branch (latest release) does not have it anymore, removed with this commit: Update for FFmpeg 6 · uvjustin/PyAV@bc04cb7 · GitHub
So v10.1.1 is newer than main? And is it necessary to not declare a missing variable for FFmpeg v6 support? Looks like FFmpeg v4.3 support was removed more as part of some cleanup, which does not add any other value.
@uvjustin pinging you here as this repo/fork has no issues section. I hope you are open to re-add FFmpeg v4.3 support with this little non-intrusive non-breaking patch.