[mythtv-users] tuning two-card systems ?

Maarten mythtv at ultratux.org
Tue Oct 19 19:59:18 UTC 2004

On Tuesday 19 October 2004 16:53, Michael J. Lynch wrote:
> Adam Felson wrote:

> >You're still misreading your cpu useage.  There's *absolutely* no way
> >you're running two cards with no cpu useage.  Impossible.  Absolutely.
> >When I ran two cards on an Athlon XP 3000, I typically got 30% useage
> >for the card processes alone and another 25% per transcode process.  If
> >I did mpeg4 encoding in real time, I got 30%/card.
> >Nowadays I'm running two pvr-250s an one bttv (bt878) card.
> He said 0% IDLE not 100% idle.  Anyway, it's hard to believe that he's
> not getting
> any jerking, hiccups, or artifacts when there is no CPU time left.

Yes! Thank you.  Hope that finally clears that up.
About the hiccups, I have now noted some blips in the audio, like when 
sentences are cut short or words concatenated.  Not too obvious, but it's 
certainly there.  So that explains everything.

> >>I notice that my two bttv cards are not what you'd call exactly in
> >>sync, where the tuners are concerned.  If one card gives good picture,
> >>the other is just slightly off-channel so the colors are too
> >>pronounced, or I get stripes and other interference.  Now what I wonder
> >>is this, can one finetune channels per-card, or is the channel
> >>frequency globally defined for all cards ?
> >
> >I've never had color problems.  Perhaps you have a defective card or are
> >running an old version of video4linux.

Nope.  The cards are not defective.  I have three cards here, and just for fun 
I had their channel freqencies printed out when perfectly tuned.  You'll note 
that each card has just ever so slightly different frequency:

Haup TV express		MIRO PCTV			Pinnacle PCTV
247.0625				247.6250				247.2500
263.0000				263.6250				263.2500

Resulting in B/W, stripes, no sound, bad picture, etc.

> >You shouldn't need per/card finetuning as they're receiving the same
> >signal.  Spend the $35 and replace the defective card.

That's easy for you to say. Of course they receive the same signal, but here I 
am, TELLING you that despite that, I see small tolerances in their tuning.
Are you saying I'm making all this up ? You sure seem to be.

But okay, let's suppose you are right and I am wrong.  Can you then please 
tell me which two of the three cards I tested are the defective ones, and 
thus which card left is the only good one ? 

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