PitchShift

class audioflux.PitchShift(radix2_exp=12, slide_length=1024, window_type=WindowType.HANN)

Pitch shift algorithm

Parameters
radix2_exp: int

fft_length=2**radix2_exp

slide_length: int

Window sliding length.

window_type: WindowType

Window type for each frame.

See: type.WindowType

Examples

Read voice audio data

>>> import audioflux as af
>>> audio_path = af.utils.sample_path('voice')
>>> audio_arr, sr = af.read(audio_path)

Compute pitch shift

>>> pitch_shift_obj = af.PitchShift(radix2_exp=12, slide_length=1024, window_type=af.type.WindowType.HANN)
>>> audio_arr1 = pitch_shift_obj.pitch_shift(audio_arr, n_semitone=6, samplate=sr)
>>> # af.write('./audio_arr1.wav', audio_arr1, sr)

Show plot

>>> yin_obj = af.PitchYIN(samplate=sr)
>>> pitch_arr, _, _ = yin_obj.pitch(audio_arr)
>>> pitch_arr1, _, _ = yin_obj.pitch(audio_arr1)

>>> import matplotlib.pyplot as plt
>>> fig, ax = plt.subplots()
>>> times = np.arange(len(pitch_arr)) * (yin_obj.slide_length / sr)
>>> ax.scatter(times, pitch_arr, s=2, label='Original')
>>> ax.scatter(times, pitch_arr1, s=2, label='Pitch Shift')
>>> ax.set_ylim(200, 750)
>>> ax.legend()
../_images/pitchShift-1.png

Methods

pitch_shift(data_arr, n_semitone[, samplate])

Compute the time stretch
pitch_shift(data_arr, n_semitone, samplate=32000)

Compute the time stretch

Parameters
data_arr: np.ndarray [shape=(…, n)]

Audio data array

n_semitone: int

Pitch shift in semitone. -12 <= n_semitone <= 12.

samplate: int

Sample rate

Returns
arr: np.ndarray [shape=(…, n)]