- From: Jack Lang <fw23@dial.pipex.com>
- Date: Wed, 1 Sep 1999 00:06:43 +0100
- To: <www-tv@w3.org>
> > > >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
Received on Tuesday, 31 August 1999 19:09:14 UTC