• ### Fourier analysis

I’m looking to do some Fourier analysis, finding the amplitude of an arbitrary, relatively small number of dominant frequencies and phases. My intention is then to reassemble the sounds using different waveforms to find interesting artifacts.

I guess it’s possible that someone has already built such a patch, and I’d love to see it. But I’m having a hard time understanding how to use the FFT objects in general, and I’d love some help building the first, analytical phase of this project.

Game and graphic designer, sci fi illustrator & author, teacher, sound hacker, plus some other shit.

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• @JoshuaACNewman A while back I was wondering about the relationship between FFT coefficients and the RMS amplitude of the input signal, and as a side project built something that did the inverse FFT by adding together the sines and cosines term by term to reconstruct the original signal. I wanted to test if I really understood what the coefficients meant and came up with an interesting animation. Maybe it might be useful to you? manual inverse FT 3.pd

Definitely check out all the I series Audio examples in the help system, that's mostly where I learned the practical FFT stuff from. Something that was hard for me to figure out about the real FFT is that it really only spits out the terms 1 to N/2+1, because the terms in the upper half are negative frequencies that are related to the positive frequency terms in the lower half. Term 1 is DC and term N/2+1 is Nyquist, and neither of those have negative frequency cousins in the upper half, so their coefficients represent the whole amount of those components, whereas the others only represent half (being split evenly between positive and neg frequency terms).

I hope I'm not making things more confusing.

• http://www.pd-tutorial.com/english/ch03s08.html was a great help for me back in time.

• @kyro This is incredibly helpful. Thank you!

Game and graphic designer, sci fi illustrator & author, teacher, sound hacker, plus some other shit.

| Posts 4 | Views 1824
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