Subject: Re: AUDITORY Digest - 29 Jul 2002 to 30 Jul 2002 (#2002-117) From: Ian Knopke <knopke(at)MUSIC.MCGILL.CA> Date: Wed, 31 Jul 2002 10:03:20 -0400Marius, There is lots of source code on the net to do fourier transforms. Here are two packages http://www.fftw.org/ http://www.library.cornell.edu/nr/bookcpdf.html (section 12) This a good online book which explains the principles behind the fourier transform: http://www.dspguide.com/pdfbook.htm If you already have the data in 512 byte array then the hardest part is done. Good luck! Ian Knopke PhD Music Technology McGill University > Hello everyone, > > I am in desperate need of a way to determine the frequency content of a > 'raw' amplitude-time sample. I know that Fourier Transform can do this, but > all of the texts I have read are at the advanced level, and quite frankly I > have no idea what they are talking about. > > The raw data is in the form of a 512 byte array, defined as char > rawdata[512]. This array is continually filled by my microphone audio > grabbing code. Now I need to be able to pass this array to a function which > would fill another array, say fourierdata, with the frequency information. > > If anyone can be of assistance, I would really appreciate it. Specifically, > if you can supply me with C code to implement such a fourier function, I > would be very greatful. > > Thank you, > Marius Myburg