[speex-dev] integerization

[Steve Underwood]

Tom Bäckström wrote:

> Hey.
>
>    The problems with Levinson -type algorithms and integrization are 
> well known. Older codecs have usually solved the problem by using 
> Schur decomposition for inversion of the autocorrelation matrix 
> instead of Levinson. Another solution sometimes used is to use double 
> precision - in this case you probably could code some pseudo-64bit 
> implementation (using only 32bit commands), but that can become quite 
> complex. I would recommend Schur. Both solutions require naturally 
> more computations than Levinson, but that's what you get :)
>    If you're unfamiliar with Schur I'd be glad to help, or you can 
> check out any standard matrix computation manual, e.g. Golub, "Matrix 
> comuptations". 

As you said, the Schur recursion is the standard trick in most vocoders, 
so you can find an implementation in most vocoder source code. Take care 
not to copy an implementation that has restrictions, though.

Regards,
Steve

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