Here I'm gonna give some tricks/facts about Fast Fourier Transform, and how to use it.
the size of the FFT (also called resolution) gives you a greater accuracy as the number is higher.
To perform higher resolution, you also need more samples.
The formula is:
Samples Required = 1000 * FFTSize / SampleRate
So to calculate a 1024 bins FFT on a 44100Hz file, you need:
1000*1024/44100 = 23.21 milliseconds worth of data (so let's say 24 :)
The formula to find the Bin from a frequency is:
So if our FFT is 512 bins, and our file samplerate is 44100Hz, then the bin for 440Hz is:
512*440/44100 = 5.10
Which means that most of the energy for the frequency is in the Bin 5, and a small part of it is in the bin 6.
As opposite, the formula to find frequency from a bin is:
So the Bin 35 of a 512 FFT (sample rate as 44100Hz) is:
35*44100/512 = 3014.64Hz
Most of the time, some high frequency bins will be very low (harmonics).
To help this , you can use the following nodes:
That's it for the moment.
I will add some help patches to try to explain some features, and add new ones as well :)
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