[mythtv-users] problem with audio underruns on 720p only

[Greg Zornetzer]

Hi all,
I am running mythfrontend on a Core 2  6550 dual core machine with a
motherboard Nvidia 7100 display.  Transport is xv-blit.  CPU usage doesn't
seem to be a problem with HD content (~25-50% usage from top in 720p or
1080i mode)
I am using the RPM version of mythtv-0.21 from rpmfusion.org.  This happens
with both the released -13 RPM and the newer -14 RPM in rpmfusion's testing
directory for fc9.  I'm running this on fedora core 9.

When I play 720p, either in live tv mode, or freshly recorded, I get the
following (recorded with -v playback):

NVP: Video is X.xxxx frames ahead of audio, doubling video frame interval to
slow down
(repeated several times)
WriteAudio: buffer underrun

In this case, X.xxxx is somewhere between about 7 and 12.
This is accompanied by stuttering of the audio every second or so.

I noticed that there was a bug that got fixed a few months ago regarding
audio buffering with 720p data (see http://svn.mythtv.org/trac/ticket/5749),
but the fix for this (included with the newest testing version of the rpm
from rpmfusion), doesn't fix the problem.

I have noticed that if I transcode the 720p recording using the default
settings, the transcode will replay flawlessly.  So, it's some kind of
problem with mythtv interpreting the data coming right off the TV line.
That's sort of good news - this way we can at least use the recordings that
are made.

Note that there is no problem with playback of 1080i material.

I believe that some others may be seeing the same problem.  I think that the
problem described here may be the same:
http://mythtv.org/pipermail/mythtv-users/2008-December/240895.html

I do have 'extra audio buffering' selected in the configuration for mythtv -
I saw that asked before.
Any suggestions?
Thanks,
-Greg
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