[vorbis] Spectrum duplication (2)

[Sune Foldager]

Christian Buchner wrote:

> [...]Also you would have to think about how to code all this auxilliary
> data in a very efficient way.

Well I don't know how they do it for mp3pro, and it's probably not 
public information, but whatever they add to the mp3 is not much.

> I've previously played with applying the concept of "motion vectors"
> to audio (both along the temporal axis as well as along the
> frequency axis). I got pretty good results coding the power
> spectrum. But the phase was too random to profit from this coding
> trick (I used an FFT based codec, not a MDCT).

I was thinking the same thing when I tried imagining how they could 
have done. They may of course choose to ignore certain things, but I 
don't know what ignoring phase would lead to in terms of perceived 
quality. It sounds like a pretty bad idea though :-P.


-- 
Sune.

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