[vorbis-dev] Why LSP?

[Monty]

> Well, you're correct that cepstrum be implementing a very similar idea. In 
> fact I'm encoding the LSP(log(envelope)) so in a way it's a closer parallel 
> than is obvious ;-)  The reason I'm not quantizing the DCT is that LSP 
> quantization does not produce ripple and irregularity throughout the envelope 
> like quantizing a DCT would (and the DCT quantization error would tend to be 
> greatest at the edges).  LSP quantization produces a more localized, 
> predictable effect with less work.

Whoops sorry about the poor editing ...

"You're correct that the cepstrum implements a very similar idea. In 
fact I'm encoding the LSP(log(envelope)) so in a way it's a closer parallel 
than is obvious ;-)  The reason I'm not quantizing the DCT is that LSP 
quantization does not produce ripple and irregularity throughout the envelope 
like quantizing a DCT would (and the DCT quantization error would tend to be 
greatest at the edges).  LSP quantization produces a more localized, 
predictable effect with less work."

Also note that LSP is a frequency domain representation of an IIR filter...

Monty

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