Re: TV Glossary

From: Jack Lang (fw23@dial.pipex.com)
Date: Tue, Aug 31 1999


Message-ID: <01ba01bef405$7f313e20$0a8db40a@ntl.com>
From: "Jack Lang" <fw23@dial.pipex.com>
To: <www-tv@w3.org>
Date: Wed, 1 Sep 1999 00:06:43 +0100
Subject: Re: TV Glossary


>
>
> >Program - a collection of related video, audio and/or data in a
> >single "file".  This is also generically called "content".
>
> So a Program has a definite, limited size. Right?

It's size may not be known beforehand - for example coverage of a cricket
match or formulae one race.
Programs may also be part of a series.
Do programs include commercials (I vote not - commercials etc should be
programs in their own right). Programs usually have a single content author
organisation.

>
>
> >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.
>
> Query:
> what does multiplexing mean in this case?
> Two possibilities - breaking up a Program Stream to insert other Program
> Streams (like commercials) - and multiple unrelated Program Streams being
> transmitted at the same time (for instance normal programming + teletex)

There is the concept of a single service transport stream, although there
are cases were different TV stations time-share a single service transport
stream
>
>
> >Content Author - usually a studio (Disney, ABC Studios) that creates
> >video, audio, and "data" or some aggregation of these.

The components may be seperately authored and then aggregated by a studio

The program may be comissioned by another party, or by a network.
> >
> >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.
>
Channel usually means from one network.
>
> >Network - company that authors and aggregates content and distributes
> >it (ABC).
> >
> >Transport Company - a company that aggregates and emits (usually in
> >cable or satellite) a collection of channels (DIRECTV).  This is also
> >sometimes referred to as a "network", but usually confuses folks when
> >it is.
>
> I'll assume that network-owned transport companies can be described as a
> Transport Company plus a Network, rather than confusing the terms.
>
>
> >Broadcaster - company that emits radio waves (KABC).
>
> Is a Broadcaster always a special case of Transport Company?
>
No - ntl: is a Broadcaster (we own radio masts, among other things), but not
a Transport company
A Transport company does things like collect PPV subscriptions.
A cable company is a special sort of broadcaster - emitting signal along its
private wires, but may also collect subscriptions on behalf of Transport
Companies
Sattelite companies (like Astra) are also by this definition Broadcasters

>
> >Affiliate - broadcaster (KABC) that gets most of its content from a
> >network, and thus has an affiliation to that network (ABC).
> >
> >Feed - the serialized stream of content from a network.
>
> Is a Feed a special case of a Program Stream?

A simplified view might be

Author(s) ->Network->Transport company ->Broadcaster
             program     service                      transport

In the UK, for example

Studio->Channel4->OnDigital->ntl:

However sometimes the same corporation performs multiple functions. On the
other hand there may be other specialist stages (like editing, adding
captions, and different switching centres and play-outs) that complicate the
picture.

Jack