[FFT] -> [1/3 octave analysis] ?
Hi all,
I'm diving into FFT data manipulation in Max, and I'd like to convert it into 1/3 octave bands. Any Max wizards here who can point me in the right direction? Your insights would be greatly appreciated!
hmm... fffb~ might be more suited depending what you want to do.
Anyway, you just want to know "which bins correspond to which octaves", which is basically a "frequency to midi" conversion... https://en.wikipedia.org/wiki/Piano_key_frequencies
offset, divide and interpolate.
an fft with 4096/4096 at 44.1 kHz offers bands of 10.7666 Hz distance each (starting with 0. to 10.7)
an 1 octave eq would have bands of f.e. 25, 50, 100, 200 Hz, an 1/3 octave eq works likewise. using mtof to go from linear to logarithmic seems a good idea.
converting the amplitude values for the proposed bands to fft bins is a bity tricky, but in theory it is simple.
fft does not work very well to remodel peak/notch filters in the lower range. for analysis only, fffb~ should be fine.