[opendtv] Re: (No Date: Tue, 28 Sep 2004 10:30:37 -0400

  • From: "John Willkie" <johnwillkie@xxxxxxxxxx>
  • To: <opendtv@xxxxxxxxxxxxx>
  • Date: Thu, 14 Oct 2004 23:43:13 -0700

So, it's going to happen by your decree?

Ah, the bugaboo of DVB Harmonization.  I've read the document several times,
and I've examined the ATSC code point registry as well.  DVB Harmonization
largely came down to one thing:  don't use the PIDs reserved for DVB-SI.  If
I'm not mistaken, the issue isn't not to use program number 1, it's the
lowest PID assigned to the lowest program_number.  In due course, MPEG-2
establishes the lowest PID at decimal 48.  That insures no conflict with
DVB-SI.

(For the uninitiated, in many (but not all) ATSC stations, program_number 1
is assigned PID 16.  That is (somewhat unwisely, IMHO) hardwired in DVB-SI
for one of the DVB-SI tables.

Your argument tends to disprove your point.  If it's just a number, why is
it so hard for broadcasters to not change a single number in their transport
stream?

I noticed something when I demodulated my first off-air signal.  A station
that was putting, in the section of the PAT (PID = 0), the packetid for
PSIP.  This is outside of ATSC practice, but it's standard practice in DVB
countries, where program_number = 0 in the PAT provides the PID of the NIT.

I've looked for a DVB document that deals with ATSC harmonization.  Still
looking, and I have about 2+ GB of DVB documents.

It's not just a number, and it takes two to tango.  ATSC has met DVB
half-way on this, and DVB has done nothing except whine about the
"non-standard" Americans going their own way.  'Twas ever thus.

And, I need to point out the disconnection in your argument.  DVB-SI is
mandatory.  PSIP is mandatory per the ATSC and now per the FCC.  A/58 is a
recommendation.  You can't say that the route to solve these issues is
broadcasters following a mere recommendation: last time I checked,
recommendations were voluntary.

That's why MPEG stepped in.  Table conflicts solved; EPG integration a
non-issue, and nobody does anything about it.  I suspect it's another reason
why EchoStar does not fully support integrated 8-VSB/Dish receivers, and why
it's easy for DirecTV to offer same.  DirecTV uses an early version of PSIP,
and I can only assume that it has the same three hour blocks as does
terrestrial and cable PSIP.

John Willkie

-----Original Message-----
From: opendtv-bounce@xxxxxxxxxxxxx
[mailto:opendtv-bounce@xxxxxxxxxxxxx]On Behalf Of Terry Harvey
Sent: Thursday, October 14, 2004 9:39 PM
To: opendtv@xxxxxxxxxxxxx; opendtv@xxxxxxxxxxxxx
Subject: [opendtv] Re: (No Date: Tue, 28 Sep 2004 10:30:37 -0400


The modulation mode in PSIP is simply a number: if needed a 'COFDM'
modulation mode number could have been included under the modulation
mode.  The modulation mode is therefore a non-issue. I feel the issue is to
ensure that there are no conflicts is the PSIP/ DVB-SI schemes.

Recall that ATSC A/58 from 1996 is the "ATSC/DVB Harmonization"
recommendation. Note that it was the basis to provide some sort of harmony
to minimize table conflicts between ATSC and DVB. Also note that many ATSC
broadcasters still ignore the recommendation in A/58 not to use 'Program 1'
in A/58.

Terry Harvey



At 07:41 PM 10/14/2004 -0700, John Willkie wrote:

>For each virtual channel emitted in the 8-VSB, there is a modulation mode
>parameter.  There are provisions in A/65 for analog and digital services,
>and NTSC and 8/16 VSB modulation.  In ATSC A/81 (satellite ATSC) there are
>provisions for a variety of modulation modes.  No provision for COFDM.
>
>You asserted that COFDM could have been permitted without any change in
>PSIP. I challenged that.
>
>The problem is symmetrical: there is no provision in DVB-SI for NTSC or
8/16
>VSB.
>
>So, they both don't recognize the other.  To make COFDM useful in TV sets
>that also support VSB, there has to be common ground in the metadata
>schemes, beyond MPEG-2 SI (PAT) and PSI (PMTs).  I also am unaware of any
>way at the MPEG-2 level to signal modulation mode -- that's effectively
>"user private" with the users being DVB and ATSC.




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