[Vorbis-dev] Floor1 encode/decode and FLOOR1_fromdB_LOOKUP

[xiphmont at xiph.org]

On Fri, Aug 21, 2009 at 7:58 AM, Jesús Díaz
Vico<jesus.diaz.vico at gmail.com> wrote:
> Hello,
>
> I have two questions concerning floor1 encoding/decoding. First I'll ask
> about the FLOOR1_fromdB_LOOKUP table: what is it's purpose? Is it to convert
> the amplitude differences between [floor1_Y] values to a dB scale?

from a dB scale, not to.

> And, if
> I'm right with that, here comes the 2nd question: when render_line0 is used
> to encode floor1, then floor1_inverse2 must be used in decode (in order to
> convert to dB scale), and, in the other hand, if render_line is used to
> encode, then floor1_inverse1 must be used in decode (render_line converts to
> dB and therefore floor1_inverse1 gets the amplitudes in dB). If all my
> suppositions are right, is there any recommendation or something like that
> to decide whether to use one combination or the other?

...huh?  Completely lost too :-)

encoding and interpolation are done in dB, and then the resulting
curve is converted to linear.

Monty