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

[Greg Zornetzer]

Hi all,
Unfortunately, I'm reading the list from a digest, so I'm having some
difficulty sending replies messages sent to the thread.
Anyway, replying to George Mari's question:

I had been referred to Setup->TV Settings->Playback->Extra audio buffering
being turned on.

I tried turning on Setup->General->Aggressive sound card buffering.
It made the stuttering a little better, but did not seem to fix the
underlying problem - I can still see the underruns in the log.  Thanks very
much for the suggestion, though.

-Greg

On Sun, Dec 7, 2008 at 6:59 PM, Greg Zornetzer
<gzornetzer.lists at gmail.com>wrote:

> 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
>
-------------- next part --------------
An HTML attachment was scrubbed...
URL: http://mythtv.org/pipermail/mythtv-users/attachments/20081207/fd63d5a8/attachment.htm