[PD] fft newbie - rifft~ filter

Frank Barknecht fbar at footils.org
Wed Jul 2 19:28:53 CEST 2008

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)

 Frank Barknecht                                     _ ______footils.org__

More information about the Pd-list mailing list