- Looks a tiny bit harder in mpegps_probe() for a valid start code. This is

needed to detect some files produced by pvr-250/350 capture cards.
- Adds AC3 audio support to the mpegts demuxer, and makes it a little more
tolerant of bad files.
patch by (Isaac Richards <ijr at po dot cwru dot edu>)

Originally committed as revision 2028 to svn://svn.ffmpeg.org/ffmpeg/trunk