speed perturb with sox

deepspeech/frontend/audio.py

@@ -22,6 +22,7 @@ import resampy
 from scipy import signal
 import random
 import copy
+import sox
 
 
 class AudioSegment(object):
@@ -323,11 +324,15 @@ class AudioSegment(object):
         """
         if speed_rate <= 0:
             raise ValueError("speed_rate should be greater than zero.")
-        old_length = self._samples.shape[0]
-        new_length = int(old_length / speed_rate)
-        old_indices = np.arange(old_length)
-        new_indices = np.linspace(start=0, stop=old_length, num=new_length)
-        self._samples = np.interp(new_indices, old_indices, self._samples)
+        # old_length = self._samples.shape[0]
+        # new_length = int(old_length / speed_rate)
+        # old_indices = np.arange(old_length)
+        # new_indices = np.linspace(start=0, stop=old_length, num=new_length)
+        # self._samples = np.interp(new_indices, old_indices, self._samples)
+        tfm = sox.Transformer()
+        tfm.speed(speed_rate)
+        self._samples = tfm.build_array(
+            input_array=self._samples, sample_rate_in=self._sample_rate)
 
     def normalize(self, target_db=-20, max_gain_db=300.0):
         """Normalize audio to be of the desired RMS value in decibels.

deepspeech/frontend/augmentor/speed_perturb.py

@@ -13,35 +13,71 @@
 # 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.
+    """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
         
-    :param rng: Random generator object.
-    :type rng: random.Random
-    :param min_speed_rate: Lower bound of new speed rate to sample and should
+        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.
-    :type min_speed_rate: float
-    :param max_speed_rate: Upper bound of new speed rate to sample and should
+            max_speed_rate (float): Upper bound of new speed rate to sample and should
                 not be larger than 1.1.
-    :type max_speed_rate: float
-    """
+            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.
 
-    def __init__(self, rng, min_speed_rate, max_speed_rate):
+        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_speed_rate = min_speed_rate
-        self._max_speed_rate = max_speed_rate
+        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 transform_audio(self, audio_segment):
         """Sample a new speed rate from the given range and
@@ -52,6 +88,13 @@ class SpeedPerturbAugmentor(AugmentorBase):
         :param audio_segment: Audio segment to add effects to.
         :type audio_segment: AudioSegment|SpeechSegment
         """
-        sampled_speed = self._rng.uniform(self._min_speed_rate,
-                                          self._max_speed_rate)
-        audio_segment.change_speed(sampled_speed)
+        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)

examples/aishell/s0/local/data.sh

@@ -25,7 +25,7 @@ python3 ${MAIN_ROOT}/utils/build_vocab.py \
 --unit_type="char" \
 --count_threshold=0 \
 --vocab_path="data/vocab.txt" \
---manifest_paths "data/manifest.train.raw" "data/manifest.dev.raw"
+--manifest_paths "data/manifest.train.raw"
 
 if [ $? -ne 0 ]; then
     echo "Build vocabulary failed. Terminated."

examples/aishell/s1/conf/augmentation.config

-[
-    {
-        "type": "shift",
-        "params": {"min_shift_ms": -5,
-                   "max_shift_ms": 5},
-        "prob": 1.0
-    }
-]

examples/aishell/s1/local/train.sh

 #! /usr/bin/env bash
 
-# train model
-# if you wish to resume from an exists model, uncomment --init_from_pretrained_model
-export FLAGS_sync_nccl_allreduce=0
-
 ngpu=$(echo ${CUDA_VISIBLE_DEVICES} | python -c 'import sys; a = sys.stdin.read(); print(len(a.split(",")));')
 echo "using $ngpu gpus..."
 

examples/aug_conf/augmentation.config.example

@@ -14,7 +14,8 @@
     {
         "type": "speed",
         "params": {"min_speed_rate": 0.95,
-                   "max_speed_rate": 1.05},
+                   "max_speed_rate": 1.05,
+                   "num_rates": 3},
         "prob": 0.5
     },
     {

examples/tiny/s1/conf/conformer.yaml

@@ -9,12 +9,12 @@ data:
   mean_std_filepath: ""
   augmentation_config: conf/augmentation.config
   batch_size: 4
-  max_input_len: 27.0
-  min_input_len: 0.0
-  max_output_len: .INF
+  min_input_len: 0.5
+  max_input_len: 20.0
   min_output_len: 0.0
-  max_output_input_ratio: .INF
-  min_output_input_ratio: 0.0
+  max_output_len: 400
+  min_output_input_ratio: 0.05
+  max_output_input_ratio: 10.0
   raw_wav: True  # use raw_wav or kaldi feature
   specgram_type: fbank #linear, mfcc, fbank
   feat_dim: 80

requirements.txt

@@ -5,6 +5,7 @@ resampy==0.2.2
 scipy==1.2.1
 sentencepiece
 SoundFile==0.9.0.post1
+sox
 tensorboardX
 typeguard
 yacs

setup.sh

@@ -7,7 +7,7 @@ fi
 
 if [ -e /etc/lsb-release ];then
     #${SUDO} apt-get update
-    ${SUDO} apt-get install -y pkg-config libflac-dev libogg-dev libvorbis-dev libboost-dev swig python3-dev
+    ${SUDO} apt-get install -y sox pkg-config libflac-dev libogg-dev libvorbis-dev libboost-dev swig python3-dev
 fi
 
 # install python dependencies