Nice doc, I didn't knew this sad story. I've engineered with ffmpeg and was impressed with it, it's a technical open-source feat to me, the pied piper fictional hacker comes to mind. How bad we lack a single lead for the API, I now wonder if this explains that no more modernization hadn't gone to the interface.
https://github.com/mpv-player/mpv/wiki/FFmpeg-versus-Libav
It helped me make the decision (for choosing ffmpeg).