[mythtv-users] CPU power and decoding

[Jay R. Ashworth]

On Thu, Oct 07, 2004 at 06:57:30PM +0200, Milos Prudek wrote:
> > This depends on the tuner card as well: hardware MPEG cards like the
> > Hauppauge, AVer 179 and Yuan do indeed consume little horsepower
> > because, like the DVB cards, they output precompressed MPEG-2 -- they
> > do it by having an onboard co-processor that does the hard work,
> > converting electricty into heat.
> 
> This is an important point. I'd like to guess how much GHz CPU cycles 
> (very approximately) difference is there.
> 
> Could you please compare
> 
> - a PVR-250 with AMD Athlon 3GHz,
> 
> - a Pinnacle PCTV Pro  with AMD Athlon 3GHz?
> 
> When I want to record a broadcasting, and do commercial skipping, how 
> much CPU cycles (GHz, rough estimate) would be left for other unrelated 
> tasks on the PC ?

A *very* rough estimate from inhaled reports is that on a 2500MHz class
CPU you might expect a PVR card to take up maybe as much as 5-10% of
your CPU to record programs to disk, on a bad day, uphill, with a
headwind, while a non-MPEG card -- which must do the MPEG encoding on
the CPU -- might take 30-50% or more. And it's the priority task, since
you only have so much memory for buffers, and if you drop raw frames off
the card, they are Lost and Gone Forever.

Cheers,
-- jra
-- 
Jay R. Ashworth                                                jra at baylink.com
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	"You know: I'm a fan of photosynthesis as much as the next guy,
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