Created attachment 453638 [details, diff] Patch for libvpx-1.5.0 media-libs/libvpx-1.5.0 is now stable and www-client/chromium is dependant on it. The following 2 patches provide a fix to <media-libs/libvpx-1.6.0
Created attachment 453640 [details, diff] Patch for ebuild
The patch simply removes the offending VP8E_UPD_ENTROPY, VP8E_UPD_REFERENCE and VP8E_USE_REFERENCE defines from mythtv/external/FFmpeg/libavcodec/libvpxenc.c Fortunately these are unused in the rest mythtv
I've loaded this into a local overlay and will give it a try.
Confirmed that re-installing Mythtv with the updated ebuild <media-libs/libvpx-1.6.0 and the epatch is all OK 'builds successfully, records SD and HD DVB TV and plays back fine.
Thanks, fixed in git. Sorry, I accidentally blew away your attribution for the patch while rebasing. https://gitweb.gentoo.org/repo/gentoo.git/commit/?id=0aa8ee4d4cb38a693bdd7c586a6fe888c13df5e1