the output (buffer) of an FFT UGen which transforms the audio input to track. For the FFT chain, with a standard hop of half FFT size, the FFT size should be 4096 at 44.1 or 48 kHz and 8192 at 88.2 or 96 kHz sampling rate.
Number of seconds for the influence of a window on the final key decision to decay by 40dB (to 0.01 its original value). Can be control-rate modulated.
Each frame, the chroma values are set to the previous value multiplied by this chroma decay. 0.0 will start each frame afresh with no memory. Can be control-rate modulated.
A (12TET major/minor) key tracker UGen. It is based on a pitch class profile of energy across FFT bins and matching this to templates for major and minor scales in all transpositions. It assumes a 440 Hz concert A reference. Output is 0-11 C major to B major, 12-23 C minor to B minor.