[PD] fft newbie - rifft~ filter

PSPunch shima at pspunch.com
Thu Jul 3 12:17:19 CEST 2008


I wasn't quite sure till now what the overlap argument was for.
Thanks for clarifying it.

David Shimamoto

> Hallo,
> mescalinum at gmail.com hat gesagt: // mescalinum at gmail.com wrote:
>> today I start learning FFT, and after seeing the (hann) windowing 
>> function, I realized this (attached) filter with custom frequency 
>> response, but I suspect something is wrong here
>> why it sucks (given that it does)?
> First as others wrote you should use block overlaps. 
> The delay strategy, David (pspunch) suggested isn't necessary with
> overlap using [block~ 512 4] as the block~ object does an internal
> delay automatically (four times in this case)
> Then it's important for windowing that you also *window the outgoing
> signal* after the inverse FFT, otherwise you get these bad artifacts. 
> Check the I03.resynthesis.pd example in the docs for a complete
> example, the corresponding chapter in Miller's book and maybe my "FFT
> for dummies" guide here: http://footils.org/cms/show/60 (though this
> doesn't explain overlap)
> Ciao

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