Onset detection

onset_detect(*[, y, sr, onset_envelope, ...])	Locate note onset events by picking peaks in an onset strength envelope.
onset_backtrack(events, energy)	Backtrack detected onset events to the nearest preceding local minimum of an energy function.
onset_strength(*[, y, sr, S, lag, max_size, ...])	Compute a spectral flux onset strength envelope.
onset_strength_multi(*[, y, sr, S, n_fft, ...])	Compute a spectral flux onset strength envelope across multiple channels.