[mythtv] Compiling against external ffmpeg

[Matthew Grant]

Hi!

I am in the process of building a patch set against svn-trunk for
support of NZ DVB-T  I am constructing a build tree based on git, and
using git-svn to sync and rebase against mainline SVN trunk.  My use
of git is to make the patch management/munging process a lot easier -
I can check my changes.

I just want to do this crazy stuff to test ffmpeg-mt.  Is there a
procedure for doing this?  After this I propose to create a patch with
the H264 multithreaded MPEG4 decode, as well as LATM-ACC, and
Mythbuntu fixes.

At the point of 0.22 release branch I will track that as it is stabilised.

Cheers,

Matthew Grant