hi, i can not answer about the mentioned “stock library”

as i never used it, is it good? where you get it from ?

but about FFT

let us just assume you would have imported / use the

http://code.compartmental.net/minim/

sound library,

then there are examples to find like

processing IDE 3.4 / File /Examples /

Contributes Libraries / Minim / Basics /

AnalyzeSound

using that example you could make following changes ( to understand )

in

```
setup () {
//.. add
println("jingle.bufferSize() "+jingle.bufferSize());
println("jingle.sampleRate() "+jingle.sampleRate());
println("fft.specSize()"+fft.specSize());
}
```

you could even in the play loop add

```
//...
for(int i = 0; i < fft.specSize(); i++)
{
// draw the line for frequency band i, scaling it up a bit so we can see it
line( i, height, i, height - fft.getBand(i)*8 );
print(" i: "+i+" "+fft.getBand(i));
}
println("\nnext");
}
```

ok, when you talk about

512 bands

i think you mean samples ( for the FFT input buffer ) to analyze

see also: song.bufferSize()

so with 512 samples

you would get back a array

fft with 256 +1 “bands”

where [0] is not a frequency, more a average offset

and [1] a sinus what fits inside the 512 samples

and the value is the amplitude of it.

*insofar the real frequency is not known, as the samples might be 512 measurements over a month of moonshine intensity…*

only the

song.sampleRate()

brings it in relation to the real world.

now what can be in [2]?

amplitude of 2 sinus in the 512 samples…