PitchShift
Added in v0.4.0
Pitch shift the sound up or down without changing the tempo.
Under the hood, this performs time stretching (by phase vocoding) followed by resampling. Note that phase vocoding can degrade audio quality by "smearing" transient sounds, altering the timbre of harmonic sounds, and distorting pitch modulations. This may result in a loss of sharpness, clarity, or naturalness in the transformed audio.
If you need a better sounding pitch shifting method, consider the following alternatives:
- signalsmith-stretch
- Rubber Band library
- https://github.com/KAIST-MACLab/PyTSMod
- https://github.com/vinusankars/ESOLA
Input-output example
Here we pitch down a piano recording by 4 semitones:
| Input sound | Transformed sound |
|---|---|
Usage example
from audiomentations import PitchShift
transform = PitchShift(
min_semitones=-5.0,
max_semitones=5.0,
p=1.0
)
augmented_sound = transform(my_waveform_ndarray, sample_rate=44100)
PitchShift API
min_semitones:float• unit: semitones • range: [-12.0, 12.0]- Default:
-4.0. Minimum semitones to shift. A negative number means shift down. max_semitones:float• unit: semitones • range: [-12.0, 12.0]- Default:
4.0. Maximum semitones to shift. A positive number means shift up. p:float• range: [0.0, 1.0]- Default:
0.5. The probability of applying this transform.