Does anyone have any ideas on this MythTV mpeg audio issue?

Mpeg file playback (ie a recording, or a DVD, or anything else w/peg encoding) works just fine in MPlayer, Xine, VLC, etc. But the same file played in MythTV just has snap-crackle-pop sound. You can play a DVD with any of those players, but in MythTV it is just crackly noises.

Music audio (mp3, wma, etc) works fine in both standalone players and in MythTV. No issue there.

I can even play a MythTV program recording outside of the MythTV frontend with any media player application and it's fine, but try to play it within MythTV, and the only audio is the crackly sounds.

So it seems like an mpeg playback in MythTV-only issue. The ffmpeg and other "restricted" codecs are loaded from the MythTV frontend's point of view (ie in MythTV Control Centre).

All the audio settings in the frontend seem to be on page 3 of MythTV setup | General wizard, and the only ones that produce any sound just product crackly sound, and I have tried them all. I uninstalled and reinstalled the codec packages. I re-ran the MythTV setup from scratch. No change.

What do I try next?