[mythtv-users] pcHDTV with PVR-350 for output

Dan Lanciani ddl5 at danlan.com
Sat Oct 23 22:57:10 UTC 2004

|]Hmm.  From reading the hardware requirements documentation I had gotten the
|](mis?)impression that even machines slower than "state of the art" could
|]handle a dumb capture card and software display decoding at the same time.
|]That's the same number of MPEG encode/decode steps.  I don't have a good feel
|]for the cost of resampling, but I would think that going from 480p to 480i
|](which should take care of any SD stream?) would not require much computation
|]since it's only re-arranging scan lines.  Am I missing something?
|Resampling is not very expensive. But decoding HDTV in software requires 
|about a P4 3Ghz and encoding a 640x480 MPEG2 stream requires about the 
|same amount of hardware.

Then if I were watching an ATSC program and tried to start a recording from
Svideo in (or a tuner) on a dumb capture card one or both would likely fail
on a single P4/3.2GHz?

|So you are looking at a P4 6Ghz just to avoid 
|using a $35 video card with TV-out.

I'm looking at what it would take to have a general solution that will
support the same kinds of features as commercial DVRs, but of course without
annoying copy protection mechanisms.  Independence of input and output encoding
is also important to support FireWire/DV.  If the required CPU power if just
out of reach today on a single processor machine it will probably be well
within reach in a year on a dual processor machine.

As far as cheap (or even expensive) video cards with TV-out, my experience
hasn't been good, but I'll certainly give it another try.  I already have the
FX5200, though I've noticed that fast-play doesn't actually work (it shows
little spurts of fast motion, but generally gets behind).  I don't know if
that is a video card issue.  I'd really love to just feed DV to a Sony DVMC
or Miglia decoder since they produce nice NTSC timing.

				Dan Lanciani
				ddl at danlan.*com

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