hi,
first of all, as its my first post on this forum, i think i should introduce myself : i am a french student in sound engineering and i have been introduced to pure data a few month ago.
I have good knowledge of audio theory and lot of practice to, but i am not that good at programming or mathematics, eventhoug i have notions...

so, here i go with my question.

i am trying to create a simple patch with two audio input between wich i want to manually crossfade to morph them. kind of a convolved crossfader in fact.
but my problem is : how can i unpack the data that comes out of the rfft~, as puredata seems to considere it is audio signal?
or am i missing something fundamental??

cheers,
pierre.

@ClaudiusMaximus said:

->
convolve ->
->

=

-> rfft ->
* -> irfft ->
-> rfft ->

where * is complex multiplication (a+bi) * (c+di) = (a*c-b*d)+(a*d+b*c)i

http://en.wikipedia.org/wiki/Convolution

so if i understand right, programing:

in1-> rfft -> A in2-> rfft ->C
-> Bi ->Di

and then (A*C-B*D)-> irfft -> out
(A*D+B*C)->

should make a convolution of in1 and in2 ??

@boonier said:

There are a number of handy objects here if you want to avoid the confusion of fft
http://www.sarc.qub.ac.uk/~elyon/LyonSoftware/MaxMSP/FFTease/

nice stuff thanks!
anyway i did not already manage to performe what i want
looks loke a holly grail i'll not reach that soon

ok,
first of all, i d like to thank everyone for paying attention to this topic.

after reading your answers, thinking a bit, and working on my laptop, here is what i came up with as a joined file.
looks like i get closer, but it still doesn't do what i want, wich should be an audio morphing...

if someone feals kind enough to throw an eye at my patch, it could be great support.

http://www.pdpatchrepo.info/hurleur/New_Folder.rar

I have sent my [rfft~] outputs to tables (thank you obiwannabe), but i do not manage tu unpack the serie of data that comes out of it...
I joined my patch to this message, maybe someone will feel kind enough to throw it a quick glance and tell me where i am wrong?

http://www.pdpatchrepo.info/hurleur/convolvedcrossfade.pd