[vorbis-dev] Why LSP?

[Monty]

> could represent my envelope with about 8-12 DCT coefficients and could vector
> quantize it with enough (for me) precision with about 10 bits (It was a
> [3500-8000] Hz envelope and I was getting ~3.5 dB distortion with an 8-bit
> vector quantizer). I don't know whether the 50 bits is an important contribution
> to the total bitstream, but I'm sure there'd be a way to reduce that (if it's
> worth it, of course).

OK, so similar.  I need less distortion than that, but that's just an issue of 
throwing more bits.  50 bits is about 3% of a 128kbps stereo stream.

Have you looked at implementing the equivalent of floor0 using modified 
cepstrum?  It would be a reasonably easy thing to design as a drop in 
replacement and it would be interesting to see how it performs.  I don't see 
an obvious benefit to it (indeed I also see no immediate drawback either 
although I think LSP is still slightly less work and more stable), but I 
haven't looked at it in detail.

Monty

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