[vorbis] had a thought on peeling last night

Daniel Schregenberger npfdd at gmx.ch
Mon Dec 23 13:09:45 PST 2002

 ('binary' encoding is not supported, stored as-is)
> Daniel wrote-
> >Did you mean to take like the first half of the packet (with wathever
> >frequencies in there)? If yes, that's probably how peeling works. 
> That's precisely what I was saying. But for the next part of your reply, what
> I meant was for the server to do the peeling instead - pass the "base"
> through, then cause the peeler on the server to break bits off one of the end
> of the "reconstitution" streams to adjust for the bandwidth.

Ah, I think I got your idea: the server provides every listener a stream, with
individually adjusted bandwith. And your method is a speed improvement over
peeling for everybody in a seperate task. This would probably be a nice idea.
Since the parts that are individual can be very small with the server sending a
base stream and individual additions.
Don't know if it actually could work...depends on the internal format of Vorbis
and the "peel-addons".

> I wrote-
> >> Is it possible to convert an existing vorbis stream into a peelable stream
> >> just by reorganising the bits?
> >
> Daniel responded with-
> >Hmmm...as far as I got it: the streams (files) Vorbis 1.0 produces are
> >already
> >peelable. (There exist a few *inoffical* tools to do it; search the archives
> >for links.) It's just that the result isn't that good. With a little work on
> >it, the quality could be (much?) better for peeled streams/files.
> Sure, if we encode 10 CDs' worth of audio to Vorbis 1.0, then wish to peel it
> to a lower bitrate, then it could be done right now, but for what I
> understand, a q6 stream peeled to the same bitrate as a q1 stream, will
> probably sound worse than a q1.

That's correct.

> So what I wanted to know was, is it possible to take a current
> stream & reorganise the bits to give a current peeler the best possible
> output?
> This would be useful for batch processing, in a radio station or by a DJ that
> has a 100-CD collection of Vorbis files encoded with ver1.0. They won't want
> to re-rip/re-encode/re-tag, & will want to use a simple peel function to make
> it easier on the server.

Hmmm...this an important question (I also don't want to reencode all my stuff
It also depends on the internal Vorbis format...although I think it should be
possible...I can't imagine xiph wants to change half of the vorbis format to
improve peeling. I suppose they'll think of a better way to organize the bits
and this should basicaly allow to apply it to already existing files.
But this question can't be answered right now...it heavily depends on how the
encoders change the output-style to improve peeling support, and this feature
is still to be implemented.

-- Daniel

--- >8 ----
List archives:  http://www.xiph.org/archives/
Ogg project homepage: http://www.xiph.org/ogg/
To unsubscribe from this list, send a message to 'vorbis-request at xiph.org'
containing only the word 'unsubscribe' in the body.  No subject is needed.
Unsubscribe messages sent to the list will be ignored/filtered.

More information about the Vorbis mailing list