Merge pull request #130 from xinghai-sun/feature_patch

Patchset for adding missing shift_perturb.py in PR #114.

deep_speech_2/data_utils/augmentor/shift_perturb.py

+"""Contains the volume perturb augmentation model."""
+from __future__ import absolute_import
+from __future__ import division
+from __future__ import print_function
+
+from data_utils.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)