[vorbis] what is floor?

[Carsten Haese]

On Fri, 2003-10-03 at 09:19, Vincent wrote:
> i can be more precise in my question:
> 
> i understand that a floor is a spectral image of a chanel.
> but i don't understand how the residue is calculated.

The floor is an approximation of the spectral image. The residue is
obtained by subtracting the floor (in the logarithmic sense, so actually
dividing it out) from the spectral image. The code that does this is in
_vp_remove_floor in psy.c. (In the code you see a multiplication with
the inverse from a lookup table instead of a division, because it's
computationally cheaper and achieves the same thing.)

Hope this helps,

Carsten Haese.

NB: The above information is based on my limited knowledge of Vorbis and
is not guaranteed to be correct.

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