[Fluxus] Get harmonics

[David Griffiths]

Hi Luis,

Good questions. I spent a while a few months ago tweaking this and
trying to find out how this should be done properly with limited
success.

> Which are the centered frequencies for each band, or they have any
> relation with the natural harmonics?

There is no relation to the natural harmonics, and "get harmonic" is a
bad name.

The frequency response calculated from the audio buffer (by libfftw) is
divided up based on set-num-frequency-bins in a linear manner. Each bin
is summed, multiplied by gain, and blended with the previous value to
give some smoothing. This is what you get from (gh). 

The code is in fluxus/modules/fluxus-audio/src/AudioCollector.cpp
starting line 174. You might like to have a play with how this works.

I experimented with dividing the frequency buffer up based on
logarithmic or different methods, but the linear aproach seemed to give
the most useful results. 

> Also I'm wondering if the buffersize is related to the bands width.

The bigger the buffer size the more accurate the frequency response will
be, the shorter the buffer size the more responsive it will be.

cheers!

dave