StokeBloke.com

Well gentoo needs you to chose ffmpeg or libav for update deep worlds to work. My system was moaning that libav + ffmeg were blocking each other.

The error is something like this :

[blocks B ] media-video/ffmpeg ("media-video/ffmpeg" is blocking
media-video/libav-0.8.2)

* Error: The above package list contains packages which cannot be
* installed at the same time on the same system.

(media-video/ffmpeg-0.10.2::gentoo, ebuild scheduled for merge)
pulled in by media-video/ffmpeg required by @selected

(media-video/libav-0.8.2::gentoo, ebuild scheduled for merge) pulled
in by
>=media-video/libav-0.8.1[X,encode,-jpeg2k,-mp3,-sdl,-theora,-threads,-truetype,-vaapi,-vdpau,-x264]
required by (virtual/ffmpeg-0.10.2-r1::gentoo, ebuild scheduled for
merge) 

I decided to use libav. Which appears to be the more active and stably developed.

I simply added -ffmpeg to my USE flag in /etc/portage/make.conf.

E.g :

USE="$USE -ffmpeg" #use libav

Then I removed ffmpeg from my system

sudo emerge -C media-video/ffmpeg
sudo emerge -C virtual/ffmpeg

Next was the big emerge

sudo emerge -avuDN world

which now no longer moans about blocking packages.