[vorbis] had a thought on peeling last night

[Daniel Schregenberger]

 ('binary' encoding is not supported, stored as-is)
Shawn Riley wrote:

> Daniel wrote-
> >I dont know how efficient it would be to provide even more streams. But
basicly
> >this should work by taking a q2, peeling it down to a q1, peeling this down
to
> >a q0 and peeling this down to a q-1. We then have a q-1 and the difference
from
> >each level to the next. Listening to the q2 would require to use *all 4*
> >streams.
> 
> But if in one "frame" (& I'm sure I've got the terminology wrong), but the
> peeler discards the q2 stream, then takes only the low frequency bits
> from the q1 stream, & takes the complete q0 & q-1 streams, would that
> give us a q0.5 stream?

Hmmm...I think Vorbis is a bit more complex than just a simple high/lowpass
combination. :)
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. (Don't know
exactly) And now I also know what you mean: By having two streams, you could
get any quality between the lower one and the higher one, by
"client-side-peeling". I just don't see exactly what it's good for: you could
take all of the second stream, cause you need to recieve/send it anyway, and
who refuses better quality if its "for free" :)

> Is it possible to convert an existing vorbis stream into a peelable stream
just by reorganising the bits?

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. There are
plans to work on this sometime, but other things are more important right now.

-- Daniel

<p>Teamwork is essential -- it allows you to blame someone else.
--- >8 ----
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