[mythtv-users] Audio/Video Stutter on one particular HD channel.

[Josh]

Josh wrote:
> Affected system is:
> Motherboard: Asus P5N7A-VM
> Onboard Video: Geforce 9300
> CPU: Core2Quad Q6600
> Sound: SB Audigy4 Value
> 1GB DDR2
> 40GB sata HD.
>
> Running Gentoo Linux,
> mythtv ~ # uname -a
> Linux mythtv 2.6.27-gentoo-r7 #6 SMP PREEMPT Tue Feb 10 11:10:31 CST 2009
> i686 Intel(R) Core(TM)2 Quad CPU Q6600 @ 2.40GHz GenuineIntel GNU/Linux
> Mythtv version 0.21-fixes
> media-tv/mythtv-0.21_p19046  USE="aac alsa dvb dvd ieee1394 lirc mmx
opengl
> perl python xvmc (-altivec) -autostart -debug -directv -fftw -jack -lcd"
> VIDEO_CARDS="nvidia" 0 kB
>
> Audio is handled by Audigy4 value, through coaxial/spdif
> It's a standalone frontend, backend is on another machine.
>
> Apparently only one channel is affected, with the audio buffer underruns
and
> dropping video frames to resync with audio.
> I have disabled audio by setting the audio device in mythfrontend to
'NULL',
> video playback is silky smooth, no dropped frames at all.
> Mabye it was a hardware issue, so I removed the Audigy4 and tried using
> onboard audio analog to my TV speakers. That resulted in worse
performance,
> with nearly all channels stuttering occaisionally.
>
> I've checked for conflicting IRQ's, my Audigy sound card is using IRQ 18
and
> is not shared. Unsure about onboard, have not tested, it is disabled when
> the Audigy is installed.
> My 'mythfrontend -v playback' is located here:
> http://rafb.net/p/mkLEhL42.html
> I was playing back a recording from the affected channel while dumping the
> logfile, so all the errors at the end are related.
>
> A clip from the HD stream is hosted here:
> http://www.megaupload.com/?d=WX0KIIFC - Keep in mind that after about 1-2
> seconds, playback would stutter
>
> Although I have virtually no proof to back this theory up, I belive the
> issue is related to audio moreso than video.
> I'm not sure what else to try.
>
> ANY help is appreciated!

I have just bought this motherboard too, for my office desktop. Ok! ok!
with an....um...accessory capability of playing HD content using vdpau..
mea culpa. Mea minima culpa since I only have the E6600 Core2Duo.

I notice that you only have one Gig of memory. This board uses main RAM
for the video buffers. And we have seen here that good HD video needs a
512Meg ram video card. So it probably needs that amount allocated to
video in the BIOS (somewhere weird in the BIOS...cannot remember where).
That ALSO means that you are running 'the rest' out of 512Meg of RAM.

You might try borrowing another 1Gig memory stick so you have 2Gig and
see what happens. As to why it is only one channel: is it possible that
that channel is the only one transmitting in a particular mode, such as
1080i or 720p, so that the board is a little more stressed on that
channel, than on the others?


In other news. Did you try setting up this board with a mix of PATA and
SATA drives? I cannot get the PATA drives recognized AT ALL if I plug in
a SATA drive. The SATA drive always ends up being recognized as /dev/sda
even though the boot order section of the BIOS has completely different
drives for sda and sdb.


Geoff


Thanks for the reply, Geoff.

I bought this board for future implementation of 0.22 with VDPAU, however,
I'm currently running 0.21-fixes..

as I understand it, right now all my video card is doing is rendering, no
decoding. That's all up to the CPU which should be more than capable.

That being said, I have already purchased 2x2GB corsair 800mhz DDR2, (the
newegg special.) We'll see if that helps the issue or not when they arrive.

I am only running one 40GB SATA and one PATA DVD-RW in this sytem. it seems
that my PATA DVD-RW shows up twice in boot order, but it does not seem to
affect system configuration.
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