Yes, I see what you mean. I have digital TV at home (Cox in San Diego, CA).
They give you a set top box which enables analog TV and digital (MPEG)
to essentially co-exist. Its BOM is probably not much more than $150. It
is
not expensive to get a DiSH, either. I just don't see the major networks
pulling
the plug on analog TV. It will probably be for at least a decade that
set-top
boxes require compatibility with it.
-- Peter
> I agree HDTV is a long way off, but not digital TV, which is the same
picture
> size as analog (~ 640x480 for NTSC) but digital. DirectTV is digital TV,
at
> roughly 4-5 Mbits / second. AT&T is offering digital TV all over the
place, or
> at least claims to be - I'll see when they offer it to me, since they now
own
> my cable provider (Cablevision in Central MA US). Some estimate that
within two
> years more US homes will have digital TV than will have broadband Internet
> access.
>
> There are already digital cable-ready TVs, but you won't need one of them;
just
> a new cable box, with an MPEG decoder in it. That's what you get when you
buy
> DirectTV, so it's not a major capital investment. Cable companies want to
go
> to (non-HDTV) digital because they can get more digital than analog
channels on
> the same wire, and they are running out of analog channel space.
>
> I can see doing the CC/XDS decode from analog. That's where
closed-captions
> are, and the info that WebTV uses. I find it hard to believe that analog
ATVEF
> will catch on. By the time ATVEF content is present in "broadcasts" most
> people who would use it will be using digital cable or satellite. Note I
say
> "most people who would use it", rather than "most people". Many people
will
> stay with analog (assuming their cable company continues to even support
it!),
> but those people will probably never use ATVEF. Don't forget, around 40%
of
> US homes don't currently have a PC or Internet access, and don't plan on
> getting either. It's hard to imagine those homes using ATVEF any time
soon.
>
> Peter Kaczowka
>
>
> Peter Lohmann wrote:
>
> > > You mention "the next few years" - but in the next few years video
will be
> > > going digital; much of it already is. Isn't all the below discussion
> > > relevant only to analog video? With digital video, ATVEF-type
information
> > > wouldn't be encoded in specific scanlines, would it? Does ATVEF
address
> > > digital video?
> > >
> > > Peter Kaczowka
> >
> > For digital video (MPEG), these data streams will be separate data
> > packets.
> >
> > Analog video won't be going away anytime soon. Alot of people thought
> > HDTV would have reached critical mass last Fall, but much of it failed
to
> > materialize. This is blamed for some of these stocks (e.g., HAUP)
taking
> > a hit. Here in the US Monday Night Football looks great on HDTV, but
> > I don't have the money to fork over for an expensive TV -- especially
> > when there is not alot of content out there made for it. I think even
MNF
> > stopped broadcasting in HD.
> >
> > -- Peter
> >
> > > Peter Lohmann wrote:
> > >
> > > > > I believe the standard you're referring to is ATVEF-A, see:
> > > > >
> > > > > http://www.atvef.com/library/spec1_1a.html
> > > > >
> > > > > The ATVEF-A data is on line 21 of the odd frames, along with the
CC
> > > > > data. It's teletext-2 format (so you can differentiate it from CC
> > > > > data). Try watching some of the mid-afternoon gameshows like
Jeopardy
> > > > > where the CC and T2/ATVEF-A data are very heavily intertwined.
> > > > >
> > > > > V4L2 needs a good CC/XDS API standard. I've got three routines
I'm
> > > > > successfully using to extract the data, but I haven't sent them to
> > > > > Bill Dirks yet for approval.
> > > > >
> > > > > When you say "bar code", I think you're talking about the line-21
> > > > > signal. It begins with a clock pulse that has seven peaks. This
is
> > > > > followed by a start bit, seven data bits, a parity bit, seven more
> > > > > data bits, and another parity bit (up to two 7-bit bytes of data
per
> > > > > frame). Watching line 21 (with an analyzer like a Tektronics
VM700),
> > > > > you should always see the clock, the start and the parity bits
> > constant.
> > > > >
> > > > > You also may be talking about ATVEF-B or NABTS (which is IP over
> > > > > video). These use lines 10-20, but I don't know who's using them.
> > > > >
> > > > > In either case, you need a hefty processor to do the DSP work in
> > > > > nearly hard realtime (~2KBytes per scan line per frame to get 2
bytes
> > > > > of data), or hardware that decodes the data for you. There are a
lot
> > > > > of decoders that do the CC/XDS for you, for example, the BT835 has
a
> > > > > fifo where you can read two bytes at a time across the I2C.
> > > >
> > > > Our reference design uses the Philips SAA7114 and the Geode
> > > > processor. The decoder 'slices' the VBI data and puts it in a
special
> > > > memory region via the video port (VIP). Benchmarking shows that
> > > > we can get as much as 5MB/second (if that much data is available).
> > > > The full bandwidth of NABTS would be much less.
> > > >
> > > > In the next few years you are going to see alot of new multimedia
> > > > devices introduced to the market which use the 'live links' that
were
> > > > referred to. Many of these products will be based on Linux and
V4L2.
> > > >
> > > > -- Peter
> > > >
> > > > _______________________________________________
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> > > > Video4linux-list@xxxxxxxxxx
> > > > https://listman.redhat.com/mailman/listinfo/video4linux-list
> > >
> > >
> > >
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> > >
> >
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