There's also the fact that pre-fork FFmpeg was incredibly dysfunctional. I fully expected Libav to pull ahead very quickly due to that there were a lot of real problems with how FFmpeg operated. However, post-fork FFmpeg ended up also mostly resolving those problems (both because there were fewer developers involved that refused to work together, and because MiNi started doing a much better job as maintainer), which I don't think anyone expected.
It's also not at all obvious why the libav developers would choose to ignore the work on ffmpeg
They have pulled in some things from FFmpeg, but avoiding having to work with some of the FFmpeg developers was one of the main points of the fork. Pulling in all of Libav's changes has been a continual source of pain for FFmpeg and they've talked about halting it a few times, but it is ultimately the reason why FFmpeg is so far ahead in features now.
Comments
There's also the fact that pre-fork FFmpeg was incredibly dysfunctional. I fully expected Libav to pull ahead very quickly due to that there were a lot of real problems with how FFmpeg operated. However, post-fork FFmpeg ended up also mostly resolving those problems (both because there were fewer developers involved that refused to work together, and because MiNi started doing a much better job as maintainer), which I don't think anyone expected.
They have pulled in some things from FFmpeg, but avoiding having to work with some of the FFmpeg developers was one of the main points of the fork. Pulling in all of Libav's changes has been a continual source of pain for FFmpeg and they've talked about halting it a few times, but it is ultimately the reason why FFmpeg is so far ahead in features now.