[vorbis-dev] Vorbis

[Monty]

BTW, it's great to have someone else active on the list that's deep into audio
as well as coding :-)

> This is what I thought.. But why is the output smaller then the input?

The dynamic range of the residuals (which by far dominate the volume of the
output) is much smaller tha the original 16 bit range of the input samples.
The LSP curve is used to flatten the overal spectral dynamic range (somewhat
like in TwinVQ), and the perceivable dynamic range within any given critical
band is roughly 4-6 bits.

(The bitstreams coded right now are for testing purposes of people writing
software around libvorbis.  They're more concerned about geting their apps to
work right with the library API than the bitrate for the moment.  The codebook
backend isn't far off).

> and why isn't the output = input +/-
> rounding errors?

Hm, at a guess a combination of approximating the response curve (it can be
found exactly from the LSP, but the math is expensive) and MDCT blurring.

Monty

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