smst.models.harmonic module

Functions that implement analysis and synthesis of sounds using the Harmonic Model.

smst.models.harmonic.find_fundamental_freq(x, fs, w, N, H, t, minf0, maxf0, f0et)

Finds fundamental frequencies of a sound using the TWM (Two-Way Mismatch) algorithm.

Parameters:
  • x – input sound
  • fs – sampling rate
  • w – analysis window
  • N – FFT size
  • t – threshold in negative dB
  • minf0 – minimum f0 frequency in Hz
  • maxf0 – maximum f0 frequency in Hz
  • f0et – error threshold in the f0 detection (ex: 5)
Returns:

f0: fundamental frequency
smst.models.harmonic.find_harmonics(pfreq, pmag, pphase, f0, nH, hfreqp, fs, harmDevSlope=0.01)

Finds harmonics of a frame from a set of spectral peaks using f0 to the ideal harmonic series built on top of a fundamental frequency.

Parameters:
  • pfreq – peak frequencies
  • pmag – peak magnitudes
  • pphase – peak phases
  • f0 – fundamental frequency
  • nH – number of harmonics
  • hfreqp – harmonic frequencies of previous frame
  • fs – sampling rate
  • harmDevSlope – slope of change of the deviation allowed to perfect harmonic
Returns:

hfreq, hmag, hphase: harmonic frequencies, magnitudes, phases
smst.models.harmonic.find_peaks(N, fs, t, w, x_frame)
smst.models.harmonic.from_audio(x, fs, w, N, H, t, nH, minf0, maxf0, f0et, harmDevSlope=0.01, minSineDur=0.02)

Analyzes a sound using the sinusoidal harmonic model.

Parameters:
  • x – input sound
  • fs – sampling rate
  • w – analysis window
  • N – FFT size (minimum 512)
  • t – threshold in negative dB
  • nH – maximum number of harmonics
  • minf0 – minimum f0 frequency in Hz
  • maxf0 – maximum f0 frequency in Hz
  • f0et – error threshold in the f0 detection (ex: 5)
  • harmDevSlope – slope of harmonic deviation
  • minSineDur – minimum length of harmonics
Returns:

xhfreq, xhmag, xhphase: harmonic frequencies, magnitudes and phases
smst.models.harmonic.is_f0_stable(f0, f0_prev)

Indicates whether a fundamental frequency in this frame is stable (if it does not deviate much from the previous one).

Parameters:
  • f0 – fundamental frequency in this frame (0 if not stable)
  • f0_prev – fundamental frequency in previous frame (0 if not stable)
smst.models.harmonic.scale_frequencies(hfreq, hmag, freqScaling, freqStretching, timbrePreservation, fs)

Scales the frequencies of the harmonics of a sound.

Parameters:
  • hfreq – frequencies of input harmonics
  • hmag – magnitudes of input harmonics
  • freqScaling – scaling factors, in time-value pairs (value of 1 no scaling)
  • freqStretching – stretching factors, in time-value pairs (value of 1 no stretching)
  • timbrePreservation – 0 no timbre preservation, 1 timbre preservation
  • fs – sampling rate of input sound
Returns:

yhfreq, yhmag: frequencies and magnitudes of output harmonics