It appears the opposite is true. ffmpeg is more or less a one man show. See http://thread.gmane.org/gmane.linux.debian.alioth.multimedia... and https://lwn.net/Articles/650816/

"I think the statistics indicate that the situation is much worse than I expected. Please keep in mind that because of the daily merges, all commits that are made in Libav also appear in FFmpeg, but not the other way round. With a finger-in-the-wind estimate of subtracting the numbers in the Libav table from the FFmpeg table, the distance between Michael and the other FFmpeg developers because even more extreme."