[LAD] Harmonic generator and transfer function

fons at kokkinizita.net fons at kokkinizita.net
Wed Dec 1 13:33:35 UTC 2010

On Wed, Dec 01, 2010 at 03:13:03PM +0300, Andrew Gaydenko wrote:

> Fons, I want just polinomial transformation regardless harmonics at all. I 
> have mentioned harmonics as a result of searching a LADSPA plugin related to 
> my needings. 

Then what is your question ? All you need to do is compute the
polynomial for each input sample.
> I'm afraid direct amplitude caculation in accorance with a0...aN will produce 
> "too fast" signal deviation, resulting in exceeding fs/2 band.

Any non-linear transfer function will do this for some inputs.
If you have an x^N term, anything above Fs/(2*N) will alias.
If you want the nonlinearity without aliasing, you have to
upsample (by a factor N, with N = highest power of x used),
apply the nonlinear function, then downsample.


There are three of them, and Alleline.

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