[PD] Relationship between constant-Q and FFT - can you do it in vanilla?

[Alexandre Torres Porres]

Howdy, trying to figure the relationship between constant-Q and FFT, and if
you can make a constant-Q patch in vanilla based on [fft~]. This would be
for an android app, so it'd be good if I didn't need an external.

I was checking the [constantq~] external, which is found here
<https://github.com/grrrr/constantq> and in 'deken'. it's based on a paper
<https://www.google.com.br/url?sa=t&rct=j&q=&esrc=s&source=web&cd=1&cad=rja&uact=8&ved=0ahUKEwi7lI6svP_UAhUFW5AKHZ_nCO4QFggoMAA&url=http%3A%2F%2Facademics.wellesley.edu%2FPhysics%2Fbrown%2Fpubs%2FeffalgV92P2698-P2701.pdf&usg=AFQjCNHM8mdNm91QW_NOdtCnkap5wOgY5A>
by Puckette and Brown. I need help cause I can't read math or figure out
code reasonably well, so I don't really know how it works. It seems it
could be done just by rescaling the output of an FFT with logarithmic
values, but I could be terribly wrong.

Thing is that I already have a pd patch with a logarithmic output here
<https://github.com/porres/LiveElectronicsTutorial/blob/master/Parte%205%20-%20FFT%20e%20Sinais%20Complexos/25.FFT-IFFT_Analise-Ressintese/2.FFT/6.Log_Freq.pd>
-
this is not vanilla, but made on extended, but easily adaptable for vanilla
(I'm also attaching it).

Also, how about just having a bank of filters with center frequencies
around the tempered scale, could you have in practice the same thing as
from [constantq~]?

thanks
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