Re: [chuck-users] Using Fourier Transform

Hi Lucas, Sorry for the late reply. But since one doesn't really learn the true nature of the FFT in 5 days, I think this may still be helpful. My favorite resources for learning & teaching about FFT are: - Julius Smith's online tutorial: https://ccrma.stanford.edu/~jos/mdft/ - Ken Steigglitz's book: http://www.amazon.com/Digital-Signal-Processing-Primer-Applications/dp/0805316841/ref=sr_1_1?ie=UTF8&s=books&qid=1295230522&sr=8-1 This book will teach you not just about FFT, but about musical signal processing in general -- it's well worth the money. Both are written with music in mind. For a much higher-level overview, you can see my FFT "cheat sheet" here: http://www.cs.princeton.edu/~fiebrink/314/2010/week8/FFT_handout_2010.pdf along with code examples from that day of class here http://www.cs.princeton.edu/~fiebrink/314/2010/week8/ and scribe notes (written by a student) here http://www.cs.princeton.edu/~fiebrink/314/2010/week8/scribe_Mia.pdf Best, Rebecca On 2011-01-11, at 9:00 AM, chuck-users-request@lists.cs.Princeton.EDU wrote:

Date: Tue, 11 Jan 2011 09:27:42 -0200 From: Lucas Zawacki To: ChucK Users Mailing List Subject: [chuck-users] Using Fourier Transform Message-ID: Content-Type: text/plain; charset=ISO-8859-1

Sup guys. This is not much of a ChucK question but here goes...

I have some free time now to experiment with ChucK and I dug up some old emails from the list. There's one talking about analysing the frequency of a given signal and the short answer was to use the FFT.

I decided I would try this aproach in order to receive input from my guitar, match the frequency being played and then issue a MIDI event to another synthesizing app. The problem is that I have a very abstract understanding of the FFT (I've used it before to do simple image processing). It does makes sense to me, e.g I can visualize in my mind what the FFT of a simple sound wave would look like, but I wasn't competent enough to extract the absolute pitch data that I wanted.

Anyway can someone elaborate a little more on the topic of frequency analisys or maybe point me to a good tutorial?

I think I'll start with the wikipedia article on the Fourier Transform and see where it gets me...

-- http://www.twitter.com/lfzawacki http://www.linesocode.wordpress.com

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