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PaddleSpeech/deepspeech/frontend/augmentor/speed_perturb.py

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4.4 KiB

# Copyright (c) 2021 PaddlePaddle Authors. All Rights Reserved.
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
# http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.
"""Contain the speech perturbation augmentation model."""
import numpy as np
from deepspeech.frontend.augmentor.base import AugmentorBase
class SpeedPerturbAugmentor(AugmentorBase):
"""Augmentation model for adding speed perturbation."""
def __init__(self, rng, min_speed_rate=0.9, max_speed_rate=1.1,
num_rates=3):
"""speed perturbation.
The speed perturbation in kaldi uses sox-speed instead of sox-tempo,
and sox-speed just to resample the input,
i.e pitch and tempo are changed both.
"Why use speed option instead of tempo -s in SoX for speed perturbation"
https://groups.google.com/forum/#!topic/kaldi-help/8OOG7eE4sZ8
Sox speed:
https://pysox.readthedocs.io/en/latest/api.html#sox.transform.Transformer
See reference paper here:
http://www.danielpovey.com/files/2015_interspeech_augmentation.pdf
Espnet:
https://espnet.github.io/espnet/_modules/espnet/transform/perturb.html
Nemo:
https://github.com/NVIDIA/NeMo/blob/main/nemo/collections/asr/parts/perturb.py#L92
Args:
rng (random.Random): Random generator object.
min_speed_rate (float): Lower bound of new speed rate to sample and should
not be smaller than 0.9.
max_speed_rate (float): Upper bound of new speed rate to sample and should
not be larger than 1.1.
num_rates (int, optional): Number of discrete rates to allow.
Can be a positive or negative integer. Defaults to 3.
If a positive integer greater than 0 is provided, the range of
speed rates will be discretized into `num_rates` values.
If a negative integer or 0 is provided, the full range of speed rates
will be sampled uniformly.
Note: If a positive integer is provided and the resultant discretized
range of rates contains the value '1.0', then those samples with rate=1.0,
will not be augmented at all and simply skipped. This is to unnecessary
augmentation and increase computation time. Effective augmentation chance
in such a case is = `prob * (num_rates - 1 / num_rates) * 100`% chance
where `prob` is the global probability of a sample being augmented.
Raises:
ValueError: when speed_rate error
"""
if min_speed_rate < 0.9:
raise ValueError(
"Sampling speed below 0.9 can cause unnatural effects")
if max_speed_rate > 1.1:
raise ValueError(
"Sampling speed above 1.1 can cause unnatural effects")
self._min_rate = min_speed_rate
self._max_rate = max_speed_rate
self._rng = rng
self._num_rates = num_rates
if num_rates > 0:
self._rates = np.linspace(
self._min_rate, self._max_rate, self._num_rates, endpoint=True)
def __call__(self, x, uttid=None, train=True):
if not train:
return x
self.transform_audio(x)
return x
def transform_audio(self, audio_segment):
"""Sample a new speed rate from the given range and
changes the speed of the given audio clip.
Note that this is an in-place transformation.
:param audio_segment: Audio segment to add effects to.
:type audio_segment: AudioSegment|SpeechSegment
"""
if self._num_rates < 0:
speed_rate = self._rng.uniform(self._min_rate, self._max_rate)
else:
speed_rate = self._rng.choice(self._rates)
# Skip perturbation in case of identity speed rate
if speed_rate == 1.0:
return
audio_segment.change_speed(speed_rate)