I noticed that media-video/mkvtoolnix and its dependancies (media-libs/libebml and media-libs/libmatroska) were outdated. Here are ebuilds for the latest version!
Created attachment 18756 [details] media-libs/libebml/libebml-0.6.0.ebuild
Created attachment 18757 [details] media-libs/libmatroska/libmatroska-0.5.2.ebuild
Created attachment 18758 [details] media-video/mkvtoolnix/mkvtoolnix-0.7.1.ebuild
all in cvs