On the #gentoo channel on FreeNode, someone had the following issue, mplayer-1.1-r1 would not build. The problem was an undefined use of enum AVPixelFormat.
Much searching found that this AVPixelFormat was being introduced in the patch file mplayer-1.1-libav-9.patch, a patch for mplayer. Strangely, the fellow did not have ffmpeg-1.1 nor libav-9 installed, which I'm told were the requirements for this patch being used.
The reason I am posting this is because it seems wrong a priori for the enum to be called AVPixelFormat. FFMPEG installs libav headers that call the enum PixelFormat, which I believe is the older source. This libav patch seems to be propagating a change to a public header file that is already used, which is just wrong. Libav-9 which is at the moment masked should not be making such changes, and I hope that libav will stay masked until this change is undone.
In sum, I believe the approach of changing the enum to AVPixelFormat is wrong and should be reported upstream. The patch file mplayer-1.1-libav-9.patch should be amended to call the enum PixelFormat, and the same should happen to libav.
sounds like a non-issue these days but reassigning to the author of the patch
Looks like you have an old and unsupported (with known security issues) version of libavutil.
(In reply to Luca Barbato from comment #2)
> Looks like you have an old and unsupported (with known security issues)
> version of libavutil.
this is current stable libav I think
anyway, patch is conditional these days so it is fixed