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

[Michael T. Dean]

daworm at comcast.net wrote:

>>Extra audio buffering:
>>...
>>(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:
>>...
>>(Is almost defintely not what you--or anyone else--want.)
>>    
>>
>Ok, so I'll leave both settings off.  Easy enough!
>  
>
Actually, you will want the Extra audio buffering turned on (it should 
be on unless it causes problems).  And, since you have a PVR-250, you 
will see problems during dark scenes without it (but until you cure your 
current problems, the problems this fixes are lost in the noise).  I was 
just trying to point out that these were not the causes of the problems 
you're describing.

>>So, you do need to fix your .asoundrc.
>>    
>>
>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.
>  
>
Are you still using ALSA:spdif?  That will not work.  spdif is an alias 
that sends the stream directly to the digital output (on your card, 
hw:0,4)--which is expecting 48000Hz PCM (for PCM, that is--AC3 would 
also work, but you won't get that from NTSC broadcasts).  You'll need to 
change it to ALSA:mixed-digital or ALSA:digital or uncomment the 
appropriate lines of the .asoundrc to set your default output and use 
ALSA:default.  Note that if using OSS emulation, you'll need to set the 
default output appropriately (meaning you might as well set it).

>>>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.
>  
>
If you're using a packaged version of MythTV, it's generally installed 
in /usr; whereas a compiled-from-source version is typically installed 
in /usr/local.  Therefore, for your configuration:

chmod a+s /usr/bin/mythfrontend

>>>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?
>  
>
GF2 would probably have the same problems.  It's probably because of 
using the wrong GL libraries (i.e. the ones in X instead of nVidia's), 
but that's a whole different thread...  :)

>>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. 
>
Software.  It uses the same driver as the nVidia nForce.

>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 wouldn't necessarily say that's true.  Audio processing tends to 
require little effort from modern CPU's.  Once you configure yours 
correctly, it should work fine.

>(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?
>
Don't know about the Hercules.  The only hardware ones I have are SB 
cards with the Emu10K1, but I haven't bought a discrete sound card in 6 
years, so...

Mike