What you should know before using it:
* the tempo is assumed to lie in an interval from 90 to 180 bpm
* analysis is performed on the audio recorded during last 6 seconds
How does it work?
Beatnik extracts relative energy of the incoming audio and stores its change in time. Meanwhile, this ever-changing energy envelope is being analyzed for periodicity using autocorrelation. Once a meaningful period is found, individual beats are located in the energy envelope and averaging their adjacent distance leads directly to the tempo.
Note: The very first step in the energy analysis is transforming the audio from the time domain to the frequency domain (Fast Fourier Transform). As it might come in handy to see the frequency distribution, plot of the magnitudes is displayed at the bottom of the screen.