[vorbis] bitrtate peeling and lossless compression

[Larry Fenske]

--- ben at slumber.dhs.org wrote:
> On Thu, Mar 22, 2001 at 02:10:44AM -0500, Keith Wright wrote:
> > > From: xiphmont at xiph.org (Monty)
> > > 
> > > On Wed, Mar 21, 2001 at 11:53:49AM -0700, heard wrote:
> > > > Could I
> > > > theoretically compress my CDs to Vorbis at a rate that is lossless, and
> > > > then be able to peel those files to 128k/s or lower for a portable
> device?
> > > 
> > > Yes, that's a possible application of the idea...
> > 
> > But with a catch.  We know from Information Theory 101 that
> > there are input sequences that when "losslessly compressed"
> > get _bigger_.  Whether any of them are something you want
> > to listen to I don't know.
> 
> This isn't likely to happen with vorbis, since it's never actually
> lossless..

Now I've heard both that lossless is possible and that it's not.  It would be
wonderful if it were possible.  I could peel back depending on the device I
want to play on, and still be able to re-create the original in a year or ten
to re-encode with the (by then) new and improved vorbis.  Now, I'm saving both
the original wave file and the ogg or mp3 file.  I've hesitated re-encoding all
my waves into ogg because it's still undergoing rapid improvement.  If I could
encode into ogg, throw away the wave (even if some oggs are slightly larger),
then re-encode later I would be ecstatic (as far as digital audio goes anyway).

Larry Fenske

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