[opendtv] Re: Speaking of MPEG-4 ...
- From: Adam Goldberg <adam_g@xxxxxxxxx>
- To: opendtv@xxxxxxxxxxxxx
- Date: Wed, 17 Sep 2008 04:46:23 -0700 (PDT)
I note that A/53 contains no reference to CEA-608 at all, only CEA-708 (which
has 608 as a normative reference).
Is your complaint is that A/53 and A/72 /should/ have a normative reference to
608, because relying upon the secondary reference via 708 isn't a good idea?
My point is that A/72 makes it pretty darn clear that the captions used are the
same as in A/53. No one should have any argument about that - and no one
familiar with it should think that 608 is not included.
----- Original Message ----
From: John Willkie <johnwillkie@xxxxxxxxxxxxx>
To: opendtv@xxxxxxxxxxxxx
Sent: Tuesday, September 16, 2008 7:47:15 PM
Subject: [opendtv] Re: Speaking of MPEG-4 ...
Adam;
I’m sorry, but my reading level has been kind of heavy the
past few days. Didn’t I say early on in this thread that there was no
normative reference to CEA-608? Was I wrong on that? I guess I can run up the
reference chain, but I don’t exactly have spare time at this point; new
business just came in the door.
John Willkie
________________________________
De:opendtv-bounce@xxxxxxxxxxxxx
[mailto:opendtv-bounce@xxxxxxxxxxxxx] En
nombre de Adam Goldberg
Enviado el: Tuesday, September 16,
2008 4:33 PM
Para: opendtv@xxxxxxxxxxxxx
Asunto: [opendtv] Re: Speaking of
MPEG-4 ...
Aw, c'mon, at least read it before saying things
like there aren't normative 608 requirements....
6.4.1
Transport of Caption, Active Format Description (AFD) and Bar Data
Captions, AFD and bar data, when present, shall be carried
according to A/53, Part 4 [3], Section
6.2, as further constrained and described in 6.4.2 of this
Part.
(etc).
The
captioning is packaged slightly differently for AVC use (due to the slightly
different sort of picture-level user_data()), but retains all of the '708
packet' and AFD syntax from previous.
----- Original Message ----
From: John Willkie <johnwillkie@xxxxxxxxxxxxx>
To: opendtv@xxxxxxxxxxxxx
Sent: Tuesday, September 16, 2008 12:11:26 PM
Subject: [opendtv] Re: Speaking of MPEG-4 ...
No normative reference to CEA-608 is a major change, and
“allowed” is quite different than “required.” But, sometimes it seems
that I’m one of the few people that knows that CEA-608 captions are required to
be passed on by DTV stations.
John Willkie
________________________________
De:opendtv-bounce@xxxxxxxxxxxxx
[mailto:opendtv-bounce@xxxxxxxxxxxxx] En
nombre de Ron Economos
Enviado el: Tuesday, September 16,
2008 3:02 AM
Para: opendtv@xxxxxxxxxxxxx
Asunto: [opendtv] Re: Speaking of
MPEG-4 ...
I'm not sure what you mean by "no analog captions". Seems like
EIA-608 fields in EIA-708 user_data_registered_itu_t_t35 packets
are still allowed.
Also, stream_type 0x1B isn't exactly "new". It was added to H.222.0
in 2004.
Ron
John Willkie wrote:
Correction: stream_type 27/ 0x1B.
John Willkie
________________________________
De:opendtv-bounce@xxxxxxxxxxxxx [mailto:opendtv-bounce@xxxxxxxxxxxxx] En nombre
de John Willkie
Enviado el: Monday, September 15,
2008 1:54 PM
Para: opendtv@xxxxxxxxxxxxx
Asunto: [opendtv] Speaking of
MPEG-4 ...
The ATSC today announced the publication of ATSC Standard A/72, in two
parts (part
1) and (part 2) providing for the carriage of AVC (MPEG-4, part 10)
video within ATSC A/53 transport streams. I suspect that the first real
use of AVC will not be in A/53 transport streams, in no small part due to the
inability of legacy digital receivers to deal with AVC (for the most
part.) For what that use will be, you will have to stay tuned.
But, note that there is now a new stream_type for AVC (28 / 0x1B) , and
how this information is conveyed in PSIP.
A few highlights: finally support for still pictures, and NO ANALOG
CAPTIONS, just digital ones.
There is a press release. If you’d like a copy, and it isn’t
available from the ATSC web site, send me an email and I’ll forward it to you.
I tend to not read press releases on this type of stuff.
I’ll have support for AVC to my PSIP generator, EtherGuide Emissary,
and test the changes, before the day is out. (Turn on a dime, and give
nine cents change.)
John Willkie
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