[mythtv-users] Re: Answers about pcHDTV HD-3000 support in Myth, QAM support, and more

Grant Edwards grante at visi.com
Tue Oct 19 20:15:02 UTC 2004

On Tue, Oct 19, 2004 at 03:22:23PM -0400, Preston Crow wrote:

>>> Yes, the ATSC stuff is already MPEG2 which is why the card
>>> outputs MPEG2 for ATSC.
>> If the card is outputting MPEG2, why does the web page say that
>> it requires so much CPU to use it (1.2+ GHz)? Is doing
>> programmed I/O?  I can't believe it's not capable of bus-master
>> DMA, but the web page never mentions it.
> Everyone overestimates the system requirements for their products.

I suppose that's the save route.

> In this case, you probably don't need anywhere near that fast
> of a CPU to record HDTV.  You probably do need that to record
> NTSC TV, which is an advertised feature.  So if all you care
> about is recording HDTV, then you're probably fine with a much
> slower CPU.

So for a backend-only machine that isn't using the HDTV board
for NTSC, it wouldn't really need much CPU.

> However, if you actually want to see what you've recorded, you
> need a CPU and graphics card with sufficient combined power to
> display HDTV-resolution MPEG-2 files, and that's no simple
> chore.  From what I've heard, most people would consider
> 1.2GHz to be less than half what you need, even with a decent
> nVidia card.

But that could be a different machine, so it wouldn't require
any extra CPU for the machine with the HDTV card.  I think the
"system requirements" page needs to be a bit more clear on the
difference between the requirements for using the card to
capture a data stream and the requirements for viewing the
resulting datastream.

In theory, could one transcode to an MPEG-2 stream at a
resolution supported by a PVR-350 and use that to view the

Grant Edwards
grante at visi.com

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