[PD] fft newbie - rifft~ filter
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__
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