Add Silence Augmentation (#5476)

* add silence augmentation Signed-off-by: fayejf <[email protected]> * reflect comment Signed-off-by: fayejf <[email protected]> * fix CI Signed-off-by: fayejf <[email protected]> Signed-off-by: fayejf <[email protected]>
NVIDIA · Nov 23, 2022 · da953ae · da953ae
1 parent 27a4acc
commit da953ae
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Showing 3 changed files with 67 additions and 2 deletions.
diff --git a/nemo/collections/asr/parts/preprocessing/__init__.py b/nemo/collections/asr/parts/preprocessing/__init__.py
@@ -23,6 +23,7 @@
     Perturbation,
     RirAndNoisePerturbation,
     ShiftPerturbation,
+    SilencePerturbation,
     SpeedPerturbation,
     TimeStretchPerturbation,
     TranscodePerturbation,

diff --git a/nemo/collections/asr/parts/preprocessing/perturb.py b/nemo/collections/asr/parts/preprocessing/perturb.py
@@ -38,7 +38,7 @@
 import random
 import subprocess
 from tempfile import NamedTemporaryFile
-from typing import List, Optional, Union
+from typing import Any, List, Optional, Union
 
 import librosa
 import numpy as np
@@ -275,6 +275,45 @@ def perturb(self, data):
         data._samples = y_stretch
 
 
+class SilencePerturbation(Perturbation):
+    """
+    Applies random silence at the start and/or end of the audio.
+
+    Args:
+        min_start_silence_secs (float): Min start silence level in secs
+        max_start_silence_secs (float): Max start silence level in secs
+        min_end_silence_secs (float): Min end silence level in secs
+        max_end_silence_secs (float): Max end silence level in secs
+        rng: Random number generator
+        value: (float): value representing silence to be added to audio array.
+    """
+
+    def __init__(
+        self,
+        min_start_silence_secs: float = 0,
+        max_start_silence_secs: float = 0,
+        min_end_silence_secs: float = 0,
+        max_end_silence_secs: float = 0,
+        rng: Optional[Any] = None,
+        value: float = 0,
+    ):
+        self._min_start_silence_secs = min_start_silence_secs
+        self._max_start_silence_secs = max_start_silence_secs
+        self._min_end_silence_secs = min_end_silence_secs
+        self._max_end_silence_secs = max_end_silence_secs
+
+        self._rng = random.Random() if rng is None else rng
+        self._value = value
+
+    def perturb(self, data):
+        start_silence_len = self._rng.uniform(self._min_start_silence_secs, self._max_start_silence_secs)
+        end_silence_len = self._rng.uniform(self._min_end_silence_secs, self._max_end_silence_secs)
+        start = np.full((int(start_silence_len * data.sample_rate),), self._value)
+        end = np.full((int(end_silence_len * data.sample_rate),), self._value)
+
+        data._samples = np.concatenate([start, data._samples, end])
+
+
 class GainPerturbation(Perturbation):
     """
     Applies random gain to the audio.
@@ -779,6 +818,7 @@ def perturb(self, data):
     "speed": SpeedPerturbation,
     "time_stretch": TimeStretchPerturbation,
     "gain": GainPerturbation,
+    "silence": SilencePerturbation,
     "impulse": ImpulsePerturbation,
     "shift": ShiftPerturbation,
     "noise": NoisePerturbation,

diff --git a/tests/collections/asr/test_preprocessing_segment.py b/tests/collections/asr/test_preprocessing_segment.py
@@ -21,7 +21,7 @@
 import pytest
 import soundfile as sf
 
-from nemo.collections.asr.parts.preprocessing.perturb import NoisePerturbation
+from nemo.collections.asr.parts.preprocessing.perturb import NoisePerturbation, SilencePerturbation
 from nemo.collections.asr.parts.preprocessing.segment import AudioSegment
 from nemo.collections.asr.parts.utils.audio_utils import select_channels
 
@@ -177,3 +177,27 @@ def test_noise_perturb_channels(self, data_channels, noise_channels):
                     _ = perturber.perturb_with_input_noise(audio, noise)
                 with pytest.raises(ValueError):
                     _ = perturber.perturb_with_foreground_noise(audio, noise)
+
+    def test_silence_perturb(self):
+        """Test loading a signal from a file and apply silence perturbation
+        """
+        with tempfile.TemporaryDirectory() as test_dir:
+            # Prepare a wav file
+            audio_file = os.path.join(test_dir, 'audio.wav')
+            # samples is a one-dimensional vector for single-channel signal
+            samples = np.random.rand(self.num_samples)
+            sf.write(audio_file, samples, self.sample_rate, 'float')
+
+            dur = 2
+            perturber = SilencePerturbation(
+                min_start_silence_secs=dur,
+                max_start_silence_secs=dur,
+                min_end_silence_secs=dur,
+                max_end_silence_secs=dur,
+            )
+
+            audio = AudioSegment.from_file(audio_file)
+            ori_audio_len = len(audio._samples)
+            _ = perturber.perturb(audio)
+
+            assert len(audio._samples) == ori_audio_len + 2 * dur * self.sample_rate