The implementation is from Brossier, P. M. (2006). Automatic annotation of musical audio for interactive applications (Doctoral dissertation), which itself is a variation of the one presented in Hainsworth, S. W., & Macleod, M. D. (2003, September). Onset Detection in Musical Audio Signals. In ICMC.
The formula is:
d[k] = Log[1 + X[k]/(X[k - 1] + epsilon)]
where X[k]
is the k
th frame of the magnitude spectrogram. The result is then standardized (using Standardize[res,Mean,Max]
).