[mythtv-users] tuning two-card systems ?

Maarten mythtv at ultratux.org
Fri Oct 15 20:25:38 UTC 2004


I just managed to build my two-card (bttv cards!) system.  It works fine I 
guess, when recording two channels it is 0% idle, but still everything 
appears to get to disk just fine for now.  I've seen no jerking or hiccups or 
artifacts.  More on that setup below. First my problem...:

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 ?

If the latter, do the PVRx50 not suffer from these little tolerances ?
If the former, how does one do that ?

Back to the system.  It is an athlon 2600+, slightly(...) overclocked to a FSB 
of 195(!) instead of 166 (I'm amazed that it goes so well...).  Further, it 
has one Miro PCTV and one Haupppauge WinTV express.  My recording settings 
are: (default profile) mpeg4, 480x480, 'relative' bitrate 3000, HQ and 4MV, 
mp3 44100. Amazing.  What bugged me though, is that at any other resolution 
setting (480x400, 400x400, 480x352) the picture breaks up badly (green 
interference every odd second). Only 480x480 looks okay. That's weird innit ? 
Needless to say the system is well-cooled, it has amongst others a zalman 
cooler CU5100 I think, of which I replaced the stock 80mm fan with a 120mm 
unit (better cooling AND less noisy to boot)
It is running on one disk now instead of the raid5 array it normally has.  And 
this is also my only caveat; maybe the additional load of the raid array 
(both in interrupts and parity calulations) can still break this setup if the 
CPU load gets too high.

I really wanted to decrease the resolution a bit (when deemed neccessary).  
Does anyone know of this strange resolution bug I described above ?



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