[vorbis] what is floor? HERE IT COMES :-)

[Sebastian Gesemann]

On Fri, 3 Oct 2003, Giuliano Pochini wrote:

> I may be wrong, but the floor is a smoothed version of the frequency
> spectrum. When you subtract it from the actual spectrum you get a
> quite flat spectrum, a sort of white noise. It still contains a lot
> of information that has to be saved in order to be able to eventually
> recreate the original sound.

The semantics of floor curves depends on the strategy of
the used encoder.
It is ACTUALLY used (current libVorbis) as a smooth
quantization curve much like the quantization matrix in
JPG/MPG.

Anyway, it's up to the encoder how to calculate
floor & residue of each channels because there're
more than one possible factorization of the
specrtal vector (into flor*residue).

In general, the flor-curve is a compact coded curve to
SCALE the residue vector. (ever heard of scalefactors
in MP3?)

bye,
Sebastian

--- >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.