Does anybody know what the frequency range of auriotouch is in FFT mode? Also, where is it defined in the code if possible. I've been digging through it, but am not very familiar with FFT or frequency calculation so am not having much luck. I've also done some googling and searching on stackoverflow and have not found results there either. Thanks for the help in advance.
A:
An FFT's frequency range is (sampleRate/2)/nbins - (sampleRate/2)
The aurioTouch code doesn't set the sampleRate, but it does get the hardware's sample rate at aurioTouchAppDelegate.mm:300
So, in the case of aurioTouch, the frequency range is going to be half whatever the current hardware sample rate is.
Art Gillespie
2010-07-29 19:50:34
So is there a way to set the hardware sample rate within this, I am wanting to sample from 20Hz to 20kHz.
Ian Oswald
2010-07-29 19:58:43
when i execute it and ran a sweep through it, it didn't look like it was displaying the lower frequencies on the graph, almost like it was displaying from 1k - 20k
Ian Oswald
2010-07-29 20:30:51
This is probably because the display scale in aurioTouch is linear instead of logarithmic—a curious choice.
Art Gillespie
2010-07-31 23:00:08
How would I go about converting from a linear scale to a logarithmic scale? Is there a formula that is used or is it just how it is processed within the fft?
Ian Oswald
2010-08-02 14:08:10
A:
The default range on the app is from 0 to 22050 but the amplitude around 22050Hz is not accurate. Also, not every frequency is displayed, only every other 21.53Hz (22050/1024) is calculated.
The defaults can be modified from the auriohelper file but doubt you can go anywhere higher than 22.05KHz.
ssj
2010-09-03 10:17:36