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i am trying to understand the concepts of digital sound proceesing and i want to implement the FFT of Apple's Accelerate Framework link. In the vDSP API you can find a nice and fast FFT but unfortunately i can not set it up right. I think the documentation is really hard to understand. I am trying to FFT the signal of the iPhone's microphone. Can somebody give me a setup or some sites where i can read about this? Would be really great.

Thanks for all your answers.

  • see here: http://stackoverflow.com/questions/4505694/creating-an-iphone-music-visualiser-based-on-fourier-transform/4513801#4513801 – Itamar Katz Dec 22 '10 at 21:23
  • As Tom points out, this looks to be a duplicate of the question [Using the apple FFT and accelerate Framework](http://stackoverflow.com/questions/3398753/using-the-apple-fft-and-accelerate-framework), which has some very good answers. – Brad Larson Dec 22 '10 at 22:20
  • i saw this question but unfortunately the answers didn't help because i don't have a strong sound related background... –  Dec 22 '10 at 23:08
  • Perhaps it would be good then to start at a more basic level. FFTs are a little more advanced of a concept. What are you trying to accomplish? – Brad Larson Dec 22 '10 at 23:54
  • i am trying to get the frequencies of the user's input. –  Dec 22 '10 at 23:58

1 Answers1

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Does Aurio Touch use vDSP ? I didn't the last time I looked, but it might now. I think that you are after a power spectrum.

Found this: Audio File FFT in an OS X environment

Also Apple's example source would collapse down a bit if you deleted all the G4 ppc code...

The audio comes at you as integers: FFTs need floats. Convert with vDSP_vflt32 or similar.

Aurio touch is good cause you can see how all the callbacks work for sound i/o.

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  • When looking for accelerate examples, look for OS X stuff, as iOS support just came out in 4.0. – Tom Andersen Dec 22 '10 at 22:11
  • http://stackoverflow.com/questions/3398753/using-the-apple-fft-and-accelerate-framework - especially the long comment that explains everything. – Tom Andersen Dec 22 '10 at 22:12