I have no experience with PyFFmpeg, but from what I read on their site it appears that they are shooting for a general-purpose encoding/decoding/transcoding library + utiltities. In other words, it appears they are aiming at exposing as much FFmpeg functionality as they can.
AVbin, in contrast, is (currently) designed specifically to meet only the audio/video decoding needs of the Pyglet project. I don't believe anyone has any plans to add any other functionality to AVbin other than decoding.
Does that help?
~ Nathan
How does AVbin compare to PyFFmpeg? I've asked this on PyFFmpeg list, but haven't receive any reply yet. Would be nice if people here could add something to the thread.