NixOS/nixpkgs — pull request #839 by vcunat (2013-08-17 05:20:42+00:00)
Title: libav: major update and refactoring

Also leaving 0_8 branch, as it's compatible with older ffmpeg versions.
I'm planning that all expressions will be able to switch easily
between ffmpeg and libav (whatever default we choose, but I prefer libav).

Edited according to notes on the reverted b00313.