[mythtv-users] Re: pcHDTV and HDTV

[Brian Foddy]

I'm a bit confused as well then.  I understand the capture is
very low cpu as the stream is already mpeg encoded.  But according
to the web site for pchdtv, they recommend a 2.4GHz to allow for
full flexibility in decoding and playback.  Where XvMC comes in
I'm not fully understanding yet.  Is it hardware decoding?
Then what about overlay and other issues.  Some on this thread
have said the quality may not be so good???

But back to my original thought, I figure 1 2+Ghz cpu needed just to
playback a HD show.  The second cpu I figured would be needed
to handle other non-hd shows using standard cards.  If I stay
with the PVR250 I have, I definately save a lot there, but as 
I posted a week ago, I'm still not very impressed with the 
motion image quality.  A obvious second option is a second
lower end machine to handle non-hd encoding and everything
plays back through the high-end front-end.

As for HD bandwidth, I'm doing ok there.  I currently have 
3x73GB SCSI U2W in a software raid, but a new motherboard
I'd go up to U160, and add a 4th drive which i have.

As for 64bit or not, I'm really just looking at whether the
new Athlon64 will drop the price points on everything.  I
agree a current Athlon or fast P4/Xeon would do the trick.

Clearly, if all this isn't needed, I'm all in favor of saving
money.  I just don't want to spend say $1000 and have it not
do everything I want when $1500 would have.

There are so many options and config ideas, its enough to make
your head spin.

Brian

On Wed, 27 Aug 2003, Brandon Beattie wrote:

> I'd agree 64 bit is overkill.  Why spend the extra money when you don't
> need to?  If I had that type of money I would build a dual P4 or AMD
> and then spend the rest on hard drives to do software raid.  8 250GB
> drives would be much nicer to have than a 64 bit system.  The only
> problem facing us in HDTV's in the future will be disk space.  Current
> processors are more than enough, and the _only_ reason you would need 2
> CPU's is if you had 4 cards in a system, recording 20 shows a day and
> wanting to transcode them to other formats (mpeg4 maybe to save disk
> space).  Otherwise a single CPU and 8 250GB drives would be enough if
> you don't ever transcode.  And anything over 3Ghz isn't needed for a
> HTPC.  (Don't quote me on this in a year. ;)
> 
> A 64 bit system will give you more bandwidth, but you don't need it.
> Current systems can easily support 4 40Mb (ATSC streams are 20Mb to
> 40Mb, common is 25Mb currently).  So if you have 160Mb/s your only
> holdup will be writing to disk, not you BUS -- and thus why I'd get
> software raid on 8 drives.. Space and writing ability.
> 
> You could even use a 486 with a software raid for recording 4 HD streams
> at once.  (Possibly, havn't checked it's max pci bandwidth).  And even
> though you can use a 1.2Ghz and hardware decoding I am against it
> because you lose OSD and to e honest, I'm less than impressed with the
> video quality of the mpeg2 decoder on nvidia cards.  Upscaling an image
> looks terrible, very pixelized.  Using software decoding you can improve
> the quality some atleast.  So 2.4Ghz is a good CPU for a frontend only
> system.
> 
> Why finance a skyscaper when all you need is a home?  -- Don't waste
> your money on things you don't need.
> 
> --Brandon
> 
> On Wed, Aug 27, 2003 at 12:44:09PM -0400, Jason Schloer wrote:
> > I may be wrong on this, but for capture you shouldn't need too powerful
> > a machine. Since ATSC signals are already MPEG2 compressed to at most
> > 19.2 mbps there's not a lot to do other than write the stream to disk.
> > So throughput will be the bigger issue for multiple hdtv cards. Where
> > you will need more horsepower is on the machines displaying the stream.
> > And once Myth is optimized for xvmc, even a 1.2 Ghz machine should be
> > enough. Anyway, I gues my point is that dual cpu Athlon-64  may be a bit
> > of overkill, especially if the "normal" cards you're considering are
> > hardware encoders. I'd love to hear other peoples take on this though,
> > especially Brandon.
> > 
> > 
> > Jason Schloer
> > 
> > 
> > -----Original Message-----
> > From: mythtv-users-bounces at mythtv.org
> > [mailto:mythtv-users-bounces at mythtv.org] On Behalf Of Brian Foddy
> > Sent: Wednesday, August 27, 2003 12:19 PM
> > To: Discussion about mythtv
> > Subject: Re: [mythtv-users] Re: pcHDTV and HDTV
> > 
> > On Wed, 27 Aug 2003, Jarod C. Wilson wrote:
> > > Unfortunate digital to analog conversion necessary, but hey. (If only 
> > > I'd waited a bit longer to get my HDTV, I woulda had one w/DVI in...
> > :)
> > 
> > I hear you.  I got a 43" Hitachi in Feb, no DVI inputs.  My parents
> > just a couple weeks ago picked up a 51" Sony with DVI for almost
> > the same price.  But hey, I've had 7 months of enjoyment :)
> > 
> > Thanks for all the feedback on my question of component inputs.
> > Seems like it won't be a major stumbling block (I didn't think it
> > would).
> > Now just need to collect some money, and get the hardware.
> > 
> > Personally, I waiting to see what the Athlon-64 and newer Xeons
> > look like before I make this jump.  I could realistically see
> > a dual cpu machine with 1-2 HD cards, perhaps another 1-2 normal
> > cards.  Since my current setup can already record 3 shows on one
> > machine, I doubt I'll want anything less.
> > 
> > Brian
> > 
> > 
> > 
> > 
> 
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