Current media-video/libav-9999 forces --enable-postproc during config which fails with: Unknown option "--enable-postproc". due to postproc having been removed from libav for good. If postproc is needed (hopefully unlikely), there's http://git.videolan.org/?p=libpostproc.git;a=summary Reproducible: Always Steps to Reproduce: 1. emerge -v1 =media-video/libav-9999
Got fixed a while ago, the question whether something in portage tree actually requiers postproc is still open but I guess it's a good idea to wait till someone find and actual package that needs it (and probly files a new bug).