[vorbis] Bit pealing and streaming

[Thomas Kirk]

Hey There

Im not one of the "vorbis wizards" that you are refering to but never
the less i think i can contribute here with a minor correction :)

> > OK, now suppose you run a server like icecast 2.0, for example.
> > Will it be possible for the server to receive a suitably encoded
> > vorbis stream at a high rate, say 128kbps, and then serve up streams
> > at the right rate for various connections?
> 
> If somebody writes the code.  I don't know what icecast 2.0 does
> at this time, presumably not that.  Does it do that for sound
> encoded in some other format, or are we starting from scratch?

Hmm i think jack from the icecast team are rewriting the icecast
server from scratch and of version 2.0 it will only support vorbis
streaming ;).

> 
> > (e.g. pass the full stream on to people using high bandwidth
> > connections, strip it down for ISDN and strip it down still further
> > for modem users, all on the one server?)  If this were possible,
> > this would make life much easier for content providers, being able
> > to make one version of the content and letting the server slice and
> > dice it to suit the listener.  This would mean the need for some
> > smarts in the server and client to determine the optimal data rate.
> 
> I see no reason why that would not be possible in priciple.  At
> worst you decode the Vorbis stream to get back the original
> waveform, and then re-encode at the lower rate.

Actually this is one of the neat features of the vorbis codec or is it
the ogg format? I dont know if this will be the same with the Tarkin video
codec that is coming sometimes in the furture (how fare is it? Monty?)
Anyway what we are talking about here is called "variable bitrate
pealing" and i learn about it by reading the article by jack moffit
in this months linux journal :) I know somebody on this list have
posted the link to the article recently so im not gonna bother? The
thing with bitrate pealing if i understand it correct the scaleing
of the bitrate is implemented direct in the format which is very
neat. One could explain it like this : you encode a pice of content in
a high bitrate. The server chops of the bits of frames according to
serv the right bitrate to the client? If im wrong here please correct
me! :) Therefore there is no need to reencode since you never take the
content back to waveform but just chop of frames.

>  
> > This of course raises the issue of the processing power needed to do the
> > pealing.  Is this very resource intensive?

The hole idea behind this is to save CPU. But in detail i dont know
ofcause :)


-- 
Venlig hilsen/Kind regards
Thomas Kirk
thomas at mmstreaming.com
http://www.mmstreaming.com

If the aborigine drafted an IQ test, all of Western civilization would
presumably flunk it.
		-- Stanley Garn

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