text: # 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.
  """Contains the volume perturb augmentation model."""
  
  from deepspeech.frontend.augmentor.base import AugmentorBase
  
  
  class ShiftPerturbAugmentor(AugmentorBase):
      """Augmentation model for adding random shift perturbation.
      
      :param rng: Random generator object.
      :type rng: random.Random
      :param min_shift_ms: Minimal shift in milliseconds.
      :type min_shift_ms: float
      :param max_shift_ms: Maximal shift in milliseconds.
      :type max_shift_ms: float
      """
  
      def __init__(self, rng, min_shift_ms, max_shift_ms):
          self._min_shift_ms = min_shift_ms
          self._max_shift_ms = max_shift_ms
          self._rng = rng
  
      def transform_audio(self, audio_segment):
          """Shift audio.
  
          Note that this is an in-place transformation.
  
          :param audio_segment: Audio segment to add effects to.
          :type audio_segment: AudioSegmenet|SpeechSegment
          """
          shift_ms = self._rng.uniform(self._min_shift_ms, self._max_shift_ms)
          audio_segment.shift(shift_ms)
  