[opendtv] Re: A detail in the history of video standards

Good point, Rod.

I remember those early specs a/55, a/56 and a/57, quite well.  (A/57 is
still in force and has been modified.)

The funniest problem: you could only have programs beginning in five-minute
increments, and programs had to have lengths in increments of five minutes.
On the first read (it was the first specification document I ever read) I
realized that it wouldn't work, even at the network level.

Fortunately, Mark Eyer (author of the SI spec for digicipher when he was at
GI) worked with Art Allison, Bernie Lechner and Matt Goldman (and others) to
develop it into something that is now ready for prime time.  Programs can
now start a second apart (no waiting five minutes to make corrections) and
can be any length, in increments of a single second.

You like a fixed relationship between program number and pid; I've come to
like the flexibility.  And, the insuing complexity is a "barrier to entry."
(Hoping that I'm finally over the barrier.)

John Willkie

----- Original Message ----- 
From: "Rod Hewitt" <rod@xxxxxxxxxxx>
To: <opendtv@xxxxxxxxxxxxx>
Sent: Tuesday, August 23, 2005 11:43 AM
Subject: [opendtv] Re: A detail in the history of video standards


> Hi John.
>
> > ATSC specifications can and do co-exist in the world.  ATSC
> > has taken much care to insure that their specifications do
> > not interfere with ARIB (Japan), SCTE (Cable) and an offshore
> > suite of specifications called MPEG.  To the maximum extent
> > possible, they have also insured that their use of Pids do
> > not trample over DVB-SI.  There is also extensive harmony
> > between the ATSC's descriptors and those of ARIB, SCTE and,
> > to some extent, DVB.
>
> This I have to comment over. The original SI standard in ATSC was based
> almost 100% on Motorola's Digicipher II system used on satellite. It
> mandated a fixed program to PID relationship (not a bad idea IMHO) and
> as a result, the PMT, video and audio streams for program 1 step right
> on top of the DVB-SI Network, Service Definition and Time tables.
>
> Doesn't sound like they thought about any networks other than DCII to
> me...
>
> Cheers,
> Rod
>
>
>
> ----------------------------------------------------------------------
> You can UNSUBSCRIBE from the OpenDTV list in two ways:
>
> - Using the UNSUBSCRIBE command in your user configuration settings at
FreeLists.org
>
> - By sending a message to: opendtv-request@xxxxxxxxxxxxx with the word
unsubscribe in the subject line.
>

 
 
----------------------------------------------------------------------
You can UNSUBSCRIBE from the OpenDTV list in two ways:

- Using the UNSUBSCRIBE command in your user configuration settings at 
FreeLists.org 

- By sending a message to: opendtv-request@xxxxxxxxxxxxx with the word 
unsubscribe in the subject line.

Other related posts: