[mythtv-users] Specs

[Brad Allen]

From: "Joseph A. Caputo" <jcaputo1 at comcast.net>
Subject: Re: [mythtv-users] Specs
Date: Thu, 8 Jan 2004 16:55:54 -0500

Your message was helpful, although there are some corrections I'm
going to make.  I have both a pcHDTV HD-2000 and a Hauppauge 990
WinTV PVR 350.

> If you have an HDTV set, you might want to consider a pcHDTV card,
> which has hardware compression & can receive HDTV stream over the
        ^^^^^^^^^^^^^^^^^^^^^^^^^^
> air.

Not quite ... pcHDTV HD-2000 does NOT do nor has HW compression;
however, ATSC is already compressed, somewhere before it hits the
broadcaster's antenna, so what you receive is already compressed.  No
cable companies send out ATSC that I know of, so this is air-antenna
only.  (I assume there may or may not be an engineering issue for
this, but who cares except cable company engineers, policy makers, our
purchase spec lists, and our card suppliers, because it's what's
available to us that matters.)

When HD-2000 is receiving NTSC, it has to do so in generic
(e.g./i.e. V4L/2) no HW codecs mode, because there aren't any video
stream HW codecs available inside of it (encode or decode).  It does
however have some special ability to receive ATSC; apparently, the HW
actually does something useful to effect that (perhaps DSPing the
received waves into digital, perhaps including minimally verifying
that that digital is a possibly useful digital signal and tuning it
just a bit?  Or maybe not ...).  SW does the rest, but SW doesn't have
much to do with ATSC streams (until display decoding) ... so little,
it seems, that pcHDTV seemed to just dump HD-2000 on the market with a
base driver and SW set, and we're doing pretty well smudging our
fingers in the SW to get it to work pretty well (and because it's not
hidden code & spec, there's really no big mysteries, and no quirks
like @*##&!! #^&*@&#^ IVTV driver --- and much less SW effort is
needed to get HD-2000 to work, compared to IVTV driver --- look at the
# of poeple working on IVTV -- a lot, compared to HD-2000).

> Check elsewhere for the availability of cards that can receive HDTV
> over cable; I don't think there are any available in the U.S.
                                                    cheaply anyway

People keep saying that.  QAM or something like that.

Obviously you can get one expensively (even if only commissioning
someone to make one for you, or pretending that a rack of equipment
with a cord to connect to your cheap PC with its HD-2000 card is a
"card" if its function is identical somehow --- let's see, it would
receive QAM or whatever (from cable), convert to digital stream, then
go out an ATSC encoder (broadcasters own them so I'm sure one could be
bought, for lots of money) and then broadcaster (very week one, since
it is only going to your PC a few feet away), only to be received by
ATSC card, and then your computer has to do something with that
compressed stream.  Hm.... Myth to a '350 output?  Not exactly a
sensible setup, but it theoretically COULD work, but nothing cost
effective).  Oh yeah --- you may have to violate a liscence with the
cable company by hacking one of their digital boxes to hook up to the
mess with a big password cracking engine between the two.  What fun!

It'd be cheaper to get Echostar (which I understand you can use cheap
DVB cards to receive signal -- someone correct me, please, if I'm
wrong; once again, is it a password cracking issue?).

> Also, keep in mind that your CPU requirements will go up if you want
> to decode & play full HDTV-resolution streams (the pcHDTV will
                                                            ^^^^
> encode, but not decode AFAIK).
  ^^^^^^^

Neither.  ATSC stream already encoded before broadcast.

Very little is necessary to turn ATSC stream into program streams
(such as MPEG stream) --- so little, that Xine, Mplayer (thus
mencoder), and Myth already all have support for that, and probably
lots of other transcoders as well.  (Result is a data stream from the
broadcaster, usually MPEG2 (well, it says "mpeg1/2" when I've looked,
but I'm assuming it's MPEG2) and some audio stream (AC3 on one).)

> The PVR-350 won't help in the decoding for that, because AFAIK it
> will only decode up to DVD-resolution (720x480 or whatever).

... a bit higher for PAL, I think ... (is it true that '350s are
target built, in such a way that my '350 won't work in PAL land by me
just setting new SW & driver settings, or is that false?) ...

Overscanned (720x480), which BTW was done for a good and effective
reason: matching scan lines or something like that, and I do believe
it works, since it looks great on its own output.

BTW, most ATSC streams where I live are NOT HD, and are NOT 16:9 or
other than ~4:3 aspect ratios.  It's still a feature to get no analog
artifacts while receiving over the air, though, even if it forces you
to tune your digital well enough not to get digital artifacts; with
digital, there is a point at which it just works, and that's as good
as you can get it, whereas with analog, there's always more to tune.
The crossover point right now is such that digital gets OK before
analog does, in my area when receiving TV, but of course the best best
best best best is always superexpensive analog (unless the original
was digital, which in that case, so be it).

But everything we're talking about is already far worse than perfect,
since it's compressed at some point anyway.

The main reason I jumped to get the HD-2000 card, though, is the
Broadcast Flag; apparently, because so few of us will have access to
HW like HD-2000, broadcasters will continue to broadcast unencrypted
video, but it won't be legal to buy HD-2000 cards after 2004.  I plan
to stock as many as I can afford between now and then.

If someone else makes a good used market by buying more than they want
right now, that'd sure make me feel more secure ... but at $200 each
(rounding up; I think it's $190 or $180 or something), they are a bit
pricy for a bare-bones no big codecs card (which only receives
antenna).  I still want a whole bunch ... two for every local
broadcaster for every house I might live in (a cold spare for each
active one in use, with full channel coverage in every location).  For
this house, that's four channels times two (for the cold spares), and
for another house it has to be more since it's closer to more
broadcasters, so about half a dozen to a dozen times two ... somewhere
between 8+12 and 8+24 cards will do fine (that's 20 ... 32 cards,
which at $200 each is $4,000 ... $6,400 ... ugh.  I'll get my car
first.  Like I said --- as many as I can afford, not as many as I want
...)

The idea is that there will be a lot of ATSC broadcasters soon, no
matter what, so no matter what, we can find a use for our HD-2000s,
unless and until they start doing encryption, which is a big question.