FFmpeg has released a maintenance update to its 3.0 branch on 2016-09-05 (which I completely missed till yesterday). All Avidemux ffmpeg patches still apply, I'm currently testing a local build with bundled ffmpeg 3.0.3 and bumped FFMPEG_VERSION in cmake/admFFmpegBuild.cmake:12 with as much samples as possible. It looks very good for now.
It would be a pity to withhold recent stability and security improvements in FFmpeg development from Avidemux users.
https://git.ffmpeg.org/gitweb/ffmpeg.git/shortlog/n3.0.3 (https://git.ffmpeg.org/gitweb/ffmpeg.git/shortlog/n3.0.3)
Too risky to touch ffmpeg
Just after relase for sure
Would you mind to branch for the release then, and to make a point release (or make 2.6.15 a "point" release) from the branch shortly afterwards, if 3.0.3 proves not to cause issues on the trunk? There are probably some security related bugs fixed in 3.0.3, now publicly known, it is not nice to ship a vulnerable application for weeks or months.
During the last week I did all Avidemux work and testing with FFmpeg 3.0.3 only. Zero related problems on Linux for me so far. It would be really nice to switch officially to 3.0.3 as soon as possible to get more testing on other platforms prior to the 2.6.15 release.
TIA