[mythtv-users] Various questions

kteague at speakeasy.net kteague at speakeasy.net
Mon Sep 26 15:34:58 UTC 2005

> > <snip>
> >
> > After reviewing these products, I was under the impression that they're
> > hardware *tuners* that do not perform any hardware encoding (which is left
> > to the CPU/software). They have a new HD-5000 card that appears to boast
> > more features than the previous card, with limited hardware support for
> > demux'ing, but it doesn't appear as if it does full hardware encoding. This
> > card is also able to receive unencrypted digital signals, so I believe my
> > type of setup will fall under this category, and I should be able to use
> > this card (if it's not simply just a tuner).
> >
> >
> > http://mythic.tv/product_info.php?products_id=46&osCsid=7c5c1287a18541561a83e932b1d7c8fd
> >
> > <snip>
> You are correct, they are hardware tuners and they don't perform any
> hardware encoding. The reason they don't need to do this is that ATSC video
> is already encoded and compressed into MPEG2 before it is broadcast. The
> video recorded by the HD-3000 and Air2PC cards is just streamed over the bus
> directly to the hard disk with very little CPU involvement. I have two
> HD-3000 cards and can record with both at the same time while using less
> than 5% of a 3Ghz Pentium4 CPU. Playback on the other hand, requires quite a
> bit of CPU time. I average about 85-90% CPU usage when playing back 1080i

Thanks for the info, Brian.  So I assume you're not using an nVidia card with a hardware MPEG2 decoder?  Or, are you using an nVidia card, and its' MPEG2 decoder just doesn't cut it?

- Ken

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