[mythtv-users] CPU power and decoding

[Pete Cable]

I have an athlon 2400 in my myth box. That said, in addition to
recording off of 2 pvr250s and auto-transcoding everything, I also run
an active web server and a teamspeak (voice chat) server. I never have
any problems with pauses/skipping while playing back recorded
programming.

In addition to the pvr250 presenting less of a system load, I have
found them to be much more reliable than my averTv bt848 card that I
used previously.

The way I usually pick which CPU to buy is simple. I check the prices
of all the available chips (usually AMD, Intel is just too expensive)
and I find the point where the price stops incrementing in amounts of
$10 or so and jumps into the $50+ range per model. I buy at this
point. Pricewatch.com puts the Athlon 3000/Athlon 64 2800 at this
pricepoint now. Sure you could get a slower processor, but for a few
bux extra you get a whole lot more.


On Fri, 8 Oct 2004 11:29:04 -0400 (EDT), Cory Papenfuss
<papenfuss at juneau.me.vt.edu> wrote:
> > 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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