[mythtv-users] Questions about v4l, digital cable, and theWinTV-D

Fri Mar 14 22:20:40 UTC 2003

Well, I might be able to shed a bit of light on the subject just based
on some reading I've done, but I must preface this by saying that no, I
haven't gotten it to work, and I have no clue whether the WinTV-D card
will work with the standard (yeah, I know, ambiguous) digital-cable
signal.

My understanding of the digital tv, or DTV signal is that it _is_
standardized using a transport known as ATSC (as opposed to NTSC or
PAL).  Generally (and from experience in the San Francisco area), I've
noted that channels >125 are encoded using ATSC in digital, whereas
everything below the 125channel fold is standard VHF/UHF frequencies
over cable.

The set top box does convert these out to NTSC/Pal format, and contains
some special handling for scrambled premium channels (HBO,Showtime,
Skin-emax, etc.).

My educated guess would be that ATSC and DTV are synonymous, and that
(at the very least) AT&T and Comcast have been supporting it for a
while.  Motorola has some whitepapers on the technology at their site,
albeit a tad buried.  Hauppage doesn't leave a lot of info exposed, so
what kind of promise a WinTV-D card shows in handling these signals is
pure speculation.

So I leave the group with one question, since I've been resisting buying
a "D" series card until I can confirm.  Has anyone had any success with
these cards and digital cable?

Cheers,
Aaron

-----Original Message-----
From: mythtv-users-bounces at snowman.net
[mailto:mythtv-users-bounces at snowman.net] On Behalf Of Joseph H. Fry
Sent: Friday, March 14, 2003 2:05 PM
To: 'Discussion about mythtv'
Subject: RE: [mythtv-users] Questions about v4l, digital cable, and
theWinTV-D

Digital Cable <> Digital Television

Digital Cable was designed to transport the video signal to the set top
box using digital technology in order to improve signal quality, allow
for Dolby digital surround sound, and potentially carry High Definition
TV (Digital) television signals.  The reason for digital cable boxes is
similar to the purpose for satellite boxes, to decode the digital
signal, and to provide security so only subscribed users can use the
digital signals.

I guess what I'm saying is that no, the digital tv card will not decode
digital cable signals... it is designed to support HDTV signals received
via a rooftop antenna.  (Ever notice the "High Definition where
Available" message on many network shows?)

So in your situation the only way to get digital cable signals into your
mythtv box would be to use the digital cable box to decode the signals.
And to control it with an IR blaster

I just wish they made TV cards for DSS and Digital Cable but then we'd
all have one wouldn't we. Wouldn't no analog to digital conversion be
nice!

Joe

-----Original Message-----
From: mythtv-users-bounces at snowman.net
[mailto:mythtv-users-bounces at snowman.net] On Behalf Of Ray Olszewski
Sent: Friday, March 14, 2003 3:56 PM
To: Discussion about mythtv
Subject: Re: [mythtv-users] Questions about v4l, digital cable, and the
WinTV-D

At 03:33 PM 3/14/2003 -0500, Joey Adams wrote:
>First of all I'm very impressed with what I've seen of MythTV so I've
>decided to build a machine to run it on.  I have digital cable 
>(Scientific-Atlanta decoder box) but I didn't want to have to go the IR

>Blaster route so I started looking for a tv tuner that could decode it.
I 
>found the Hauppauge WinTV-D
>(http://www.newegg.com/app/viewproduct.asp?DEPA=&submit=Go&description=
WinTV%2DD+digital) 
>that looked like it might do the job, at least it does Digital TV.
>
>DTV is the same as "digital cable" right?

The "standards" (standards? hah! we don't need no stinkin' standards)
for 
digitizing TV signals are a mess. As a general rule for TV products,
don't 
assume *anything* digital works with *anything else* digital unless you 
have specific reason to believe it does. In this case ... I don't know
for 
sure, but I believe the Hauppauge card you refer to supports some
digital 
form of broadcast TV, not any of the common digital-cable formats.

>And if it is, is the card even supported under linux?   I'm guessing
no, 
>but the only reference to the card that I found was from the middle of
2002.

 From the link above, the card appears to present to the linux-v4l
drivers 
as though it were a standard bt878 card (seemingly with some hidden, 
internal stuff to handle digital signals on some of the channels). I'd 
**guess** from this description that it does work with Linux  for
standard 
analog signals -AND- probably for standard Digital-TV signals, but -NOT-

with digital cable. I offer this only as a guess based on reading the
card 
description, though, not as a definitive answer based on actual
experience 
with it.

>I was reading through the links on the Video for Linux Resources page
and 
>apparently Hauppauge cards aren't the best supported either...

Nonsense. I've used the standard, analog-TV Hauppauge cards for over a
year 
now, and they play (the newer, bt878 ones, anyway) very well with v4l 
(specifically, the bttv module in newer kernels).

>    am I doomed to just using analog or an IR Blaster?

Yes, but not because Hauppauge cards aren't "the best supported" ...
just 
because the digitizing of cable TV remains unstandardized.

BTW,  if I am wrong in any major way here, I'd very much appreciate a 
correction. I've resisted my cable company's unending appeals to
"upgrade" 
to digital service because I too do not want to be stuck using an IR 
Blaster solution (partly because it seems like such a clunky workaround,

partly because it means renting another decoder from the cable
provider). 
So if there is a tidy way to use a v4l-based device with digital cable,
I'd 
love to learn about it.

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