[speex-dev] integerization

Jean-Marc Valin jean-marc.valin at hermes.usherb.ca
Fri Jun 27 14:12:12 PDT 2003

Le ven 27/06/2003 à 05:10, Christian Buchner a écrit :
> Hi there.
> Just a little status update how that integerization is coming along.
> I am trying to limit myself to 32 bit arithmetics. That means
> not using any __int64 or long long datatypes at any point.

If possible, it would be nice to restrict ourselves to 32x32->64
multiplies, so the code could run on almost any architecture.

> One problem that i encountered is the high dynamic range of the
> results of the autocorrelation function. Think 96db squared.
> -> 192 dB ;) That is not very desirable when used as input for
> further processing.

One thing to note here is that it is only the "relative values" that
count for the auto-correlation. That is, you can normalize it by
autocor[0] and get the same results. That should greatly reduct the
dynamic range. BTW, once normalized by autocor[0], all the
auto-correlation coef. are in the [0,1] range.


Jean-Marc Valin, M.Sc.A.
LABORIUS (http://www.gel.usherb.ca/laborius)
Université de Sherbrooke, Québec, Canada

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