[opendtv] Re: PSIP, cable guide info, and Zap2It

  • From: "johnwillkie" <johnwillkie@xxxxxxxxxxxxx>
  • To: <opendtv@xxxxxxxxxxxxx>
  • Date: Mon, 9 Jul 2007 15:53:04 -0700

John;

They made the carriage of multiple transport streams explicit in the
foresection with -c  It's also explicit deep in the text of all versions:
channels listed in the VCTs explicitly include the tsid and channel number,
and even permit the EITs to be on a different transport stream, and the
EETTs can be on a third or fourth, or ...  The field is ETM_ ... (something)
for extended text message location.

All the recent enhancements extend this: the recent proposed modification to
A/57 permitting house numbers has an explicit tsid field.

DTV-SI has a somewhat less flexible way of referencing external transport
streams, but easier in a good way, since you can tell by the pid and
table_id when the table refers to the current or outside transport stream.

I will pass on your suggestion to Jerry Whitaker of the ATSC.  I think it's
more important for it to be available on the FCC web site.

I do maintain a copy of the referenced version.  I suspect part of the issue
is that it includes amendments that weren't integrated into the main body of
the spec until the next letter version.

John Willkie

P.S.  You may not live and die by a/65, but you've earned $100 because
trying to prove you were wrong about system_time led me to two serious
errors in my code.  (Still, it doesn't look like the generator put out wrong
time.  Details to follow, timed with my bank account being replenished.

-----Mensaje original-----
De: opendtv-bounce@xxxxxxxxxxxxx [mailto:opendtv-bounce@xxxxxxxxxxxxx] En
nombre de John Shutt
Enviado el: Monday, July 09, 2007 12:42 PM
Para: OpenDTV
Asunto: [opendtv] Re: PSIP, cable guide info, and Zap2It


----- Original Message ----- 
From: "johnwillkie" <johnwillkie@xxxxxxxxxxxxx>


> John;
>
> I'd be interested in knowing what provision is in A/65C (and not in -b or
> the original) that you feel limits the ability of one station to carry the
> PSIP information for other stations.
>
> Maybe I missed a new word here or there in the latest version, but I know
> of
> no such limitation in PSIP.

Since I don't live and breathe PSIP, I qualified my statement with "I'm not
sure" because a cursory review of A/65 showed that all references for TVCT
(Terrestrial Virtual Channel Table) were to "the transport stream" which
could have been interpreted as excluding information not in the transport
stream. CVCT was more inclusive, referring to all transport streams, as one
would expect for a cable version of the standard.

However, after your challenge, I read more thoroughly and I did find one
sentence applying to Terrestrial that allows for multiple transport stream
guide data, so what was originally proposed vis a vis PBS stations is still
technically feasible, if not politically so.  A/65C, Section 5.1,
Requirement 5:

"Requirement 5: The PSIP tables shall describe all of the digital channels
multiplexed in the Transport Stream. For convenience, the tables may
optionally include information about analog channels as well as other
digital channels available in different Transport Streams."

> Also, I should point out that A/65c isn't required by the FCC: the
> 20030318
> version of A/65 is.

I know, and it mystifies me why the ATSC doesn't keep legacy versions of 
their
standards (that are referenced by the FCC as the official rules) on their 
web site.

John



 
 
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