[mythtv-users] HD Audio stutters after 30 seconds of good playback

Brian Foddy bfoddy at visi.com
Mon Aug 14 00:28:40 UTC 2006

On Sunday 13 August 2006 09:55 am, Brian Foddy wrote:
> Resending because last post never appeared.
> Using recent 0.19 fixes svn, when I play a 720p HD
> content from either ABC or Fox, the digital audio will play
> fine for about 30 seconds and then start to stutter.  If
> I FF or RW, I'll get another 30 good seconds then more stutters.
> I know its the playback because if I RR and play the same
> content again it will play fine as long as its within the 30 second
> window.  If I just pause and resume playback, the stuttering will
> resume faster but there will still be some good playback.
> This is the same machine that before couldn't play this 720 content
> at all with 0.19 straight, but the fixes tree has corrected the
> Prebuffering pauses sufficiently enough to allow watching, it plays
> pretty good.  I'm using XvMC Nvidia for all content.
> The stuttering can be heard, and I can also see my audio receiver
> status lights flickering as well.
> CBS/NBC HD content audio/video plays fine.  Audio sync for both forms is
> good.  There isn't anything on the FE console when the stutters occur.
> I've tried both the extra audio buffering and without, no
> noticeable difference.
> My frontend is config to output to /dev/adsp, via an optical cable
> to the surround sound receiver.  The receiver status shows its getting
> a full digital signal.  The sound card is a Chaintech AV710.
> CPU during playback is about 50-60% and nothing else is running
> on either the FE or BE machines.  The BE / NFS server is connected
> on a 1Gb network to the FE.  I've tried both NFS and myth:// network
> protocols.
> Does anyone have any clues to fix or how to help diagnose the
> problem (sticking dumps in code, etc).
> Thanks for the help.
> Brian

Steve Adeff,

For some reason I'm not getting most of the list posts, including
my own but I was able to read your reply on the archive.  And your
question about the modeline turned out to be right on.  I was using
a 540p modeline that worked out to be 59.59 Hz vertical according
to xvidtune.  When I tried another 540p modeline @ 59.94 the audio
stutter went away.  Thanks for the tip.  And BTW, I was using Nvidia
8762 on a kernel, NV 5600 card on a P3-1400.  Its now
handling almost every HD and AC3 digital audio I can find.  Very
sweet for a old P3 hand-me-down.

Thanks much.

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