An autocorrelation based beat tracker UGen.
The underlying model assumes 4/4, but it should work on any isochronous beat structure, though there are biases to 100-120 bpm; a fast 7/8 may not be tracked in that sense. There are '''four''' control-rate outputs, being ticks at quarter, eighth and sixteenth level from the determined beat, and the current detected tempo. Note that the sixteenth note output won't necessarily make much sense if the music being tracked has swing; it is provided just as a convenience.
This beat tracker determines the beat, biased to the mid-tempo range by weighting functions. It does not determine the measure level, only a tactus. It is also slow reacting, using a 6 second temporal window for its autocorrelation maneuvres. Don't expect human musician level predictive tracking.
On the other hand, it is tireless, relatively general (though obviously best at transient 4/4 heavy material without much expressive tempo variation), and can form the basis of computer processing that is decidedly faster than human.
'''Warning''': This UGen only works properly at 44.1 or 48.0 kHz.
- Value Params
- chain
the output (buffer) of an FFT UGen which transforms the audio input to track. The expected size of FFT is 1024 for 44100 and 48000 sampling rate, and 2048 for double those. No other sampling rates are supported.
- lock
If this argument is greater than 0.5, the tracker will lock at its current periodicity and continue from the current phase. Whilst it updates the model's phase and period, this is not reflected in the output until lock goes back below 0.5. Can be control-rate modulated.
- Companion
- object