[Vorbis] Floor1 doubts...

[Eldhelrim]

2009/11/11 <xiphmont at xiph.org>


> This mostly restates the same idea several different ways that are
> equivalent and I'm not sure where you're confused.  So let's step back
> a second...
>
> The floor encodes a continuous function and the values of that
> function are meant to be used as multipliers/ratios.  Linear floor
> multiplied by residue gives you a spectrum.
>
> The floor is encoded on a logarithmic scale (not actually decibels in
> fact, but decibels are easy to understand, so the spec discusses this
> in terms of decoding the encoded floor to decibels, then doing a
> decibel->linear conversion).  Unitless decibels are just ratios.  1 ==
> 0db, 2 == 6dB, 4 = 12dB. The coversion is a simple 20log10(linear).
>
> Is that helpful?
>
> Monty
>

Hm... I think I could summarize better my doubt in this way:

Why the greatest value the floor can have, after converting it to linear, is
1 (which would make 20log10(linear) = 0, as linear is 1)? If the floor is
the superposition of tonal and noise masks, then, if it's greatest value is
1, or 0 dB, wouldn't it be many mask values that it couldn't represent? (for
example, if the masks superposition equals to 10dB...).

Again, this is why I thought of the reference level used in the "dB" scale
to be dynamic with frequency (the mdct coefficients).
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