[mythtv-users] HDTV audio problems

[Andrew Gallatin]

I've upgraded to a recent subversion for the DVB features, but
I'm having some severe problems which I think are audio related.
I'm using alsa:spdif and both "extra audio buffering" and "aggressive
audio buffering" (both turned on after seeing these problems).
I'm seeing the problems mostly on a 720p station, and I'm using xvmc.

In live-tv, when I try to tune to a channel with 5.1 surround sound,
mythfrontend will sometimes complain:

2005-09-12 21:11:30.345 AvFormatDecoder: Video has changed from 0x0 to 1280x720.
2005-09-12 21:11:30.735 Opening audio device 'spdif'.
2005-09-12 21:11:30.736 Channels count (6) not available: Invalid argument
2005-09-12 21:11:30.736 Unable to set ALSA parameters

If I restart mythfrontend and re-enter live tv, it will work most
of the time.  It is interesting that when it doesn't work, it also
seems to prevent XvMC from working.  Or at least each time I've seen
this happen,  XvMC has failed to work.

Also, I sometimes will see a flurry of these go by, and the video will get
very, very jerky:

2005-09-12 21:53:13.142 prebuffering pause
2005-09-12 21:53:13.242 prebuffering pause
2005-09-12 21:53:13.341 prebuffering pause
2005-09-12 21:53:13.349 WriteAudio: buffer underrun
2005-09-12 21:53:13.442 prebuffering pause

Seeking forward or back will generally "re-sync" and things will return
to normal.  

I see the prebuffering pause sometimes when watching recordings
from this (or another 720p) station.   The prebuffering pause
seems much worse when xvmc is enabled, but for sports, things
are too jerky (even with a 3.0Ghz p4) to turn off xvmc.

Thanks for any help..

Drew