Setup for Apple's Accelerate FFT for the iPhone

2
votes

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.

1
iphonefftmicrophoneaccelerate-framework
see here: stackoverflow.com/questions/4505694/… - Itamar Katz
As Tom points out, this looks to be a duplicate of the question Using the apple FFT and accelerate Framework, which has some very good answers. - Brad Larson
i saw this question but unfortunately the answers didn't help because i don't have a strong sound related background... - user551640
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
i am trying to get the frequencies of the user's input. - user551640

1 Answers

0
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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.