Re: Program Stream (TV Glossary)

From: Harald Tveit Alvestrand (Harald@Alvestrand.no)
Date: Wed, Sep 01 1999


Message-Id: <4.2.0.58.19990901082940.04bd7c70@dokka.maxware.no>
Date: Wed, 01 Sep 1999 08:35:08 +0200
To: "Michael A. Dolan" <miked@tbt.com>, www-tv@w3.org (WWW TV List)
From: Harald Tveit Alvestrand <Harald@Alvestrand.no>
Subject: Re: Program Stream (TV Glossary)

At 16:58 31.08.99 -0700, Michael A. Dolan wrote:

> >>Program Stream - as defined in ISO 13818-1 for MPEG - a streaming
> >>version of a Program.
> >>
> >>Transport (Stream) - as defined by ISO 13818-1 for MPEG - a
> >>multiplexed collection of concatenated Program Streams without
> >>beginning or end.
>
> >>Channel - a Program Stream.  This is also known in DVB as a
> >>"service".
> >
> >Now I'm confused; I would have thought that a Channel would be a
>Transport
> >Stream.
>
>A channel is one Program Stream (analogous to analog TV now - you get
>some video, audio and maybe data).  A Transport contains one or more
>Program Streams multiplexed together.  This is like the cable
>company, or a digital (DVB or ATSC) system.

I've included only the relevant portions above.
I think the Program Stream definition must be wrong, since a Channel does 
not consist of only a single Program, while a Program Stream consists of "a 
streaming version of *a* Program".

If we make the definition of Program Stream read "a concatenated collection 
of  one or more Programs (in streaming versions), which has a beginning, 
but may or may not have a definite end", it fits.

                          Harald

--
Harald Tveit Alvestrand, Maxware, Norway
Harald.Alvestrand@maxware.no