#!/usr/bin/env python
# -*- coding: utf-8 -*-
"""
Deformation functions for Amen.
All functions act on an Audio object and return a modified Audio object.
"""
import librosa
from .audio import Audio
def time_stretch(audio, rate):
"""
Wraps librosa's `time_stretch` function, and returns a new Audio object.
Note that this folds to mono.
Parameters
---------
audio : Audio
The Audio object to act on.
rate : float
The stretch factor.
If rate is > 1, then the audio is sped up.
If rate is < 1, then the audio is slowed down.
A rate of `2.0` will result in audio that is twice as fast.
"""
stretched = librosa.effects.time_stretch(
librosa.to_mono(audio.raw_samples), rate=rate
)
stretched_audio = Audio(raw_samples=stretched, sample_rate=audio.sample_rate)
return stretched_audio
def pitch_shift(audio, steps, step_size=12):
"""
Wraps librosa's `pitch_shift` function, and returns a new Audio object.
Note that this folds to mono.
Parameters
---------
audio : Audio
The Audio object to act on.
steps : float
The pitch shift amount.
The default unit is semitones, as set by `step_size`.
step_size : float > 0
The number of equal-tempered steps per octave.
The default is semitones, as set by `step_size=12`.
Quarter-tones, for example, would be `step_size=24`.
"""
shifted = librosa.effects.pitch_shift(
librosa.to_mono(audio.raw_samples),
audio.sample_rate,
steps,
bins_per_octave=step_size,
)
stretched_audio = Audio(raw_samples=shifted, sample_rate=audio.sample_rate)
return stretched_audio
def harmonic_separation(audio, margin=3.0):
"""
Wraps librosa's `harmonic` function, and returns a new Audio object.
Note that this folds to mono.
Parameters
---------
audio : Audio
The Audio object to act on.
margin : float
The larger the margin, the larger the separation.
The default is `3.0`.
"""
harmonic = librosa.effects.harmonic(
librosa.to_mono(audio.raw_samples), margin=margin
)
harmonic_audio = Audio(raw_samples=harmonic, sample_rate=audio.sample_rate)
return harmonic_audio
def percussive_separation(audio, margin=3.0):
"""
Wraps librosa's `percussive` function, and returns a new Audio object.
Note that this folds to mono.
Parameters
---------
audio : Audio
The Audio object to act on.
margin : float
The larger the margin, the larger the separation.
The default is `3.0`.
"""
percussive = librosa.effects.percussive(
librosa.to_mono(audio.raw_samples), margin=margin
)
percussive_audio = Audio(raw_samples=percussive, sample_rate=audio.sample_rate)
return percussive_audio
