[mythtv-users] SPDIF, Stutter and Query for where to look for more help

daworm at comcast.net daworm at comcast.net
Wed May 4 16:59:04 UTC 2005


> Extra audio buffering:
> Enable this setting if MythTV is playing "crackly" audio and you are 
> using hardware encoding.  This setting will have no effect on MPEG-4 or 
> RTJPEG video. MythTV will keep extra audio data in its internal buffers 
> to workaround this bug.
> 
> (Has no effect unless you're using a PVR-x50 and similar, and would only 
> make a difference on dark scenes.)

Ok, I don't think that is a problem.  I am capturing mostly via firewire.  I also have a PVR-250 for any SD programs that conflict (and HD has priority), but I haven't noticed any crackly audio.
 
> Aggressive Soundcard Buffering:
> If enabled, MythTV will pretend to have a smaller soundcard buffer than 
> is really present.  This may speed up seeking, but can also cause 
> playback problems.
> 
> (Is almost defintely not what you--or anyone else--want.)

Ok, so I'll leave both settings off.  Easy enough!
 
> So, you do need to fix your .asoundrc.  I recommend starting with: 
> http://www.mythtv.info/moin.cgi/DigitalSoundHowTo#head-b318f22131b4a59eef5f28edf
> ac9160204e13719 
> .  Read the entire post and you should find the information you need to 
> modify it.  You'll need to verify/change the device for your digital 
> output, and you might as well change the "nForce" in the comments--but I 
> highly recommend you read the entire post to help you understand *why* 
> you're making these changes.

Yes, I had come to the same point, and made those changes (hw:0,4 was the only needed change to point to the digital out on this Intel board).  Unfortunately, it didn't help.
 
> > P.S. I suppose there are four other possibilities for stutter.  One, I 
> > used Jarod's guide suggestion to make mythfrontend run as root, but 
> > for some reason mythfrontend still says I need to SUID as root for 
> > smoother playback.
> 
> as root:
> chmod a+s /usr/local/bin/mythfrontend
>  
> (In section "Enabling real-time scheduling of the display thread." at 
> http://www.mythtv.org/docs/mythtv-HOWTO-5.html#ss5.4 )

On FC3, the "local" part does not apply, correct?  I think what I did didn't have the "a" (only the "+s") so I'll try that when I get home.
 
> > Two, my video sync is still USleep, as I can't run 7174 (see previous 
> > post about "split-screen" effect) and can't get OpenGL to run on 6629 
> > (crashes X when I run glxgears).
> 
> Shouldn't make that big of a difference (although I recommend fixing 
> your driver installation, anyway).

I wish I knew how.  I've installed 6629, 7167 and 7174 and the first does not allow any OpenGL apps to run, and the latter two both have the split screen problem.  I have a GF2 card I can try, but would rather use the FX5200 as I have mostly working modelines that took forever to get right.  But, if I must, I must.  After building this box over nearly two years, what's a few more weeks to get another video card, right?

> echo 1024 > /proc/sys/dev/rtc/max-user-freq
...
> immediately after boot.  If you get 1024, you're done.  If not, put the 
> echo line into your startup scripts (if you're using udev or devfs, make 
> sure it executes after the device has been created).

I'll look into that.  I think I know where it should go, but if I'm not correct I can search the archives.
 
> Regardless, you'll want to fix your audio, anyway.

Yes.  I don't know whether the AD1985 on this Intel board is a hardware or software card.  Considering it mentions AC'97 I would think it may be software based, which would mean I'd be better off just getting a new card (I have open PCI slots, although it would mean having three cards adjacent, which isn't great for airflow.  I don't really want to spend too much on a card.  Is the Hercules Digifire card hardware based?  Or should I bite the bullet and get an Audigy?

Thanks for the feedback.  It has been most helpful!

Jeff.




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