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

[Jeffrey J. Kosowsky]

Michael T. Dean wrote at about 23:27:16 -0500 on Sunday, December 7, 2008:
 > On 12/07/2008 11:09 PM, George Mari wrote:
 > > Which do you have turned on?
 > >
 > > Setup->General->(Page 3)->Aggressive sound card buffering
 > >
 > > or
 > >
 > > Setup->TV Settings->Playback->(Page 1)->Extra audio buffering
 > >
 > > For the longest time, I didn't realize these were both there as separate 
 > > options.  I saw them both from time to time, I just lumped them together 
 > > as the same option in my mind.
 > >
 > > Turning on the second one made all the difference for me certain 720p 
 > > recordings.
 > 
 > And, their effects are basically opposite.  The 2nd (Extra audio 
 > buffering) is a very good and probably everyone /should/ have it enabled.
 > 
 > The first (Aggressive sound card buffering) is generally a very bad 
 > thing, and if enabling it seems to help, your system is probably 
 > underpowered or otherwise occupied (i.e. something else is taking enough 
 > CPU to make decoding sufficient data for smooth playback in real time 
 > difficult or impossible).
 > 
 > Note, also, that--AFAIU--recently there have been a lot of reports of 
 > streams in the wild that seem to have enough offset between the audio 
 > and video streams (not A/V sync offset during playback, but offset of 
 > the streams in the transmission), that Myth (and likely most other media 
 > players)--which only decodes so far into the stream--is unable to keep 
 > sufficient audio and/or video (whichever is ahead of the other) buffered 
 > to play back without pauses.  In other words, it's quite possible the 
 > OP's provider is sending out a--well, let's just call it--"less than 
 > optimal" stream.
 > 

I am having very similar problems. But since I am watching OTA, I
don't have any one provider and I'm not sure they would all be so
simultaneously guilty.

Could the catpture card be doing something funky in displacing audio
and video streams? (I have a pchdtv5500 card)

Also, since I see this on ALL digital streams (HD or SD) could my
relatively underpowered system be exacerbating an underlying problem
and perhaps causing it to show itself more bodly?

I have an old P4 2.8GHz CPU on an Asus P4PE motherboard with a new
GeForce 6200 AGP (running at 4x) with 256MB DDR.