Hi, thank you for the quick answer!
Well now i am testing in the browser and not with the OWL actually.. because i wasn't be able to make the patch work so i supposed that with OWL wouldn't be different, but maybe i'm wrong (i am wondering if can be a browser issue. I tried with Google Chrome, MS Edge, Firefox).
Anyway trying in the browser i noticed that after the Inverse FFT if i put the buffer to zero, for instance, it not work. I'm expecting that if i set A parameter > 0.5 i hear no sound, and that is not what is happening. (i edited the code uncommenting a line after the IFFT).
Furthermore the "check" with A parameter < 0.01 that should work in any case is not working anymore after the first time i try to go over 0.5.
I hope the explanation is more clear.
Anyway the link you posted is very interesting, thanks a lot! I will definitely study it
Are FFTs the right tool to make this patch possible in C++? I mean, to make a simple pitch shifter that shift the frequency in input according to a parameter (I don't even need to keep the original signal). In other words, may I do this in time domain? (I know these questions may seem very trivial but I'm new to the world of DSP)