[mythtv-users] CPU power and decoding

Cory Papenfuss papenfuss at juneau.me.vt.edu
Fri Oct 8 15:29:04 UTC 2004


> Well I will use the PC/CPU not only for Myth, but two users will also access 
> it remotely via X Window and run Mozilla, Gimp, Kmail, OpenOffice.
 	Agreed.  That changes things a bit.
>
> From what I gathered so far in this discussion, I suppose that:
>
> with Pinnacle PCTV Pro (no mpeg), and when watching live TV with instant 
> replay - commercial skipping active, about 1,5 GHz of CPU might be consumed.

 	Good figure with some CPU to spare.  My experience has been 900MHz 
PIII was marginal to encode software captures.  If you playback at the 
same time and turn on some features like deinterlacing, it'll suck up the 
1.5GHz CPU and not have much left over.

>
> OTOH with Hauppauge PVR-250 in the same situation, the CPU impact would be 
> negligible (considering an Athlon 2500-3000 MHz class system).

 	Yes... playback (assuming Xv-support in the vid card) will 
probably take 15-20% CPU.

 	There are other non-obvious benefits to the PVR-250.  My 
experience (2 PVR-250's, and 3 BT878-based capture cards) has been that, 
although you can tell the card to capture at high-resolution like 720x480, 
you don't get any more real picture quality improvements after a certain 
point.  For the BT878-based cards that I've used, that limit is about 
400x480.  For the PVR-250's that I've used, it's about 540x480.  I have 
tested them with resolution test pattern still to quantify the numbers. 
Basically, unless you really want to use the resources to get MPEG4 
compression on the fly, the PVR-250 is the much better card (quality per 
dollar).

YMMV,
-Cory


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