Hallo, Oded Ben-Tal hat gesagt: // Oded Ben-Tal wrote: > DPCM is Differential pulse code modulation, and its possible to get an > estimate of derivative with the right predictor. While the difference > between the last two messages is an approximation of the derivative its is > a really bad one so extrapulating on 4-points is much better. (dsp theory > is really not my area but I'm sure some people will be able to explain > much better about dpcm) > What I'm looking for is a way to: > (1) store the last 3 values in the series. > (2) an estimate of the derivative should be > x0 - 1/2 * x1 - 1/4 * x2 -1/4 * x3 (where x0 is the most recent element) > (3) switch places so the x0->x1 x1->x2 x2->x3 ready to do it again.
Okay, that's not too hard to do. Attached is a solution using [expr], you could of course also use the other math-objects in Pd. I converted list-lastx.pd from [list]-abs into a subpatch here to avoid that dependency. Ciao -- Frank Barknecht _ ______footils.org_ __goto10.org__
dpcm.pd
Description: application/puredata
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