Select provider of libav* libraries

[Andreas Cadhalpun]

Hi,

On 23.06.2015 18:07, Alessio Treglia wrote:
> We are then migrating away from libav,

I've created an experimental ffmpeg branch [1] with the changes
for the transition.

Comments/testing/review are welcome. ;)

Best regards,
Andreas

1: https://anonscm.debian.org/cgit/pkg-multimedia/ffmpeg.git/log/?h=experimental