DSP

Spectral representations

stft(y[, n_fft, hop_length, win_length, …])	Short-time Fourier transform (STFT)
istft(stft_matrix[, hop_length, win_length, …])	Inverse short-time Fourier transform (ISTFT).

Magnitude scaling

amplitude_to_db(S[, ref, amin, top_db])	Convert an amplitude spectrogram to dB-scaled spectrogram.
db_to_amplitude(S_db[, ref])	Convert a dB-scaled spectrogram to an amplitude spectrogram.
power_to_db(S[, ref, amin, top_db])	Convert a power spectrogram (amplitude squared) to decibel (dB) units
db_to_power(S_db[, ref])	Convert a dB-scale spectrogram to a power spectrogram.

Time and frequency conversion

frames_to_samples(frames[, hop_length, n_fft])	Converts frame indices to audio sample indices.
frames_to_time(frames[, sr, hop_length, n_fft])	Converts frame counts to time (seconds).
samples_to_frames(samples[, hop_length, n_fft])	Converts sample indices into STFT frames.
samples_to_time(samples[, sr])	Convert sample indices to time (in seconds).
time_to_frames(times[, sr, hop_length, n_fft])	Converts time stamps into STFT frames.
time_to_samples(times[, sr])	Convert timestamps (in seconds) to sample indices.
hz_to_mel(frequencies[, htk])	Convert Hz to Mels
mel_to_hz(mels[, htk])	Convert mel bin numbers to frequencies
fft_frequencies([sr, n_fft])	Alternative implementation of np.fft.fftfreq
mel_frequencies([n_mels, fmin, fmax, htk])	Compute an array of acoustic frequencies tuned to the mel scale.