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feature_extraction_speech_to_text.py
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feature_extraction_speech_to_text.py
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# coding=utf-8
# Copyright 2021 The HuggingFace Inc. team.
#
# 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.
"""
Feature extractor class for Speech2Text
"""
from typing import List, Optional, Union
import numpy as np
import torch
import torchaudio.compliance.kaldi as ta_kaldi
from ...feature_extraction_sequence_utils import SequenceFeatureExtractor
from ...feature_extraction_utils import BatchFeature
from ...utils import PaddingStrategy, TensorType, logging
logger = logging.get_logger(__name__)
class Speech2TextFeatureExtractor(SequenceFeatureExtractor):
r"""
Constructs a Speech2Text feature extractor.
This feature extractor inherits from [`Speech2TextFeatureExtractor`] which contains most of the main methods. Users
should refer to this superclass for more information regarding those methods.
This class extracts mel-filter bank features from raw speech using TorchAudio and applies utterance-level cepstral
mean and variance normalization to the extracted features.
Args:
feature_size (`int`, defaults to 80):
The feature dimension of the extracted features.
sampling_rate (`int`, defaults to 16000):
The sampling rate at which the audio files should be digitalized expressed in Hertz per second (Hz).
num_mel_bins (`int`, defaults to 80):
Number of Mel-frequency bins.
padding_value (`float`, defaults to 0.0):
The value that is used to fill the padding vectors.
do_ceptral_normalize (`bool`, *optional*, defaults to `True`):
Whether or not to apply utterance-level cepstral mean and variance normalization to extracted features.
normalize_means (`bool`, *optional*, defaults to `True`):
Whether or not to zero-mean normalize the extracted features.
normalize_vars (`bool`, *optional*, defaults to `True`):
Whether or not to unit-variance normalize the extracted features.
"""
model_input_names = ["input_features", "attention_mask"]
def __init__(
self,
feature_size=80,
sampling_rate=16000,
num_mel_bins=80,
padding_value=0.0,
do_ceptral_normalize=True,
normalize_means=True,
normalize_vars=True,
**kwargs
):
super().__init__(feature_size=feature_size, sampling_rate=sampling_rate, padding_value=padding_value, **kwargs)
self.num_mel_bins = num_mel_bins
self.do_ceptral_normalize = do_ceptral_normalize
self.normalize_means = normalize_means
self.normalize_vars = normalize_vars
self.return_attention_mask = True
def _extract_fbank_features(
self,
waveform: np.ndarray,
) -> np.ndarray:
"""
Get mel-filter bank features using TorchAudio. Note that TorchAudio requires 16-bit signed integers as inputs
and hence the waveform should not be normalized before feature extraction.
"""
waveform = waveform * (2**15) # Kaldi compliance: 16-bit signed integers
waveform = torch.from_numpy(waveform).unsqueeze(0)
features = ta_kaldi.fbank(waveform, num_mel_bins=self.num_mel_bins, sample_frequency=self.sampling_rate)
return features.numpy()
@staticmethod
def utterance_cmvn(
x: np.ndarray,
input_length: int,
normalize_means: Optional[bool] = True,
normalize_vars: Optional[bool] = True,
padding_value: float = 0.0,
) -> np.ndarray:
# make sure we normalize float32 arrays
if normalize_means:
mean = x[:input_length].mean(axis=0)
x = np.subtract(x, mean)
if normalize_vars:
std = x[:input_length].std(axis=0)
x = np.divide(x, std)
if input_length < x.shape[0]:
x[input_length:] = padding_value
# make sure array is in float32
x = x.astype(np.float32)
return x
def normalize(
self, input_features: List[np.ndarray], attention_mask: Optional[np.ndarray] = None
) -> List[np.ndarray]:
lengths = attention_mask.sum(-1) if attention_mask is not None else [x.shape[0] for x in input_features]
return [
self.utterance_cmvn(x, n, self.normalize_means, self.normalize_vars, self.padding_value)
for x, n in zip(input_features, lengths)
]
def __call__(
self,
raw_speech: Union[np.ndarray, List[float], List[np.ndarray], List[List[float]]],
padding: Union[bool, str, PaddingStrategy] = False,
max_length: Optional[int] = None,
truncation: bool = False,
pad_to_multiple_of: Optional[int] = None,
return_tensors: Optional[Union[str, TensorType]] = None,
sampling_rate: Optional[int] = None,
return_attention_mask: Optional[bool] = None,
**kwargs
) -> BatchFeature:
"""
Main method to featurize and prepare for the model one or several sequence(s). sequences.
Args:
raw_speech (`np.ndarray`, `List[float]`, `List[np.ndarray]`, `List[List[float]]`):
The sequence or batch of sequences to be padded. Each sequence can be a numpy array, a list of float
values, a list of numpy arrays or a list of list of float values.
padding (`bool`, `str` or [`~utils.PaddingStrategy`], *optional*, defaults to `True`):
Select a strategy to pad the returned sequences (according to the model's padding side and padding
index) among:
- `True` or `'longest'`: Pad to the longest sequence in the batch (or no padding if only a single
sequence if provided).
- `'max_length'`: Pad to a maximum length specified with the argument `max_length` or to the maximum
acceptable input length for the model if that argument is not provided.
- `False` or `'do_not_pad'` (default): No padding (i.e., can output a batch with sequences of different
lengths).
max_length (`int`, *optional*):
Maximum length of the returned list and optionally padding length (see above).
truncation (`bool`):
Activates truncation to cut input sequences longer than *max_length* to *max_length*.
pad_to_multiple_of (`int`, *optional*):
If set will pad the sequence to a multiple of the provided value.
This is especially useful to enable the use of Tensor Cores on NVIDIA hardware with compute capability
>= 7.5 (Volta), or on TPUs which benefit from having sequence lengths be a multiple of 128.
return_attention_mask (`bool`, *optional*):
Whether to return the attention mask. If left to the default, will return the attention mask according
to the specific feature_extractor's default.
[What are attention masks?](../glossary#attention-mask)
<Tip>
For Speech2TextTransoformer models, `attention_mask` should alwys be passed for batched inference, to
avoid subtle bugs.
</Tip>
return_tensors (`str` or [`~utils.TensorType`], *optional*):
If set, will return tensors instead of list of python integers. Acceptable values are:
- `'tf'`: Return TensorFlow `tf.constant` objects.
- `'pt'`: Return PyTorch `torch.Tensor` objects.
- `'np'`: Return Numpy `np.ndarray` objects.
sampling_rate (`int`, *optional*):
The sampling rate at which the `raw_speech` input was sampled. It is strongly recommended to pass
`sampling_rate` at the forward call to prevent silent errors.
padding_value (`float`, defaults to 0.0):
The value that is used to fill the padding values / vectors.
"""
if sampling_rate is not None:
if sampling_rate != self.sampling_rate:
raise ValueError(
f"The model corresponding to this feature extractor: {self} was trained using a sampling rate of"
f" {self.sampling_rate}. Please make sure that the provided `raw_speech` input was sampled with"
f" {self.sampling_rate} and not {sampling_rate}."
)
else:
logger.warning(
"It is strongly recommended to pass the `sampling_rate` argument to this function. "
"Failing to do so can result in silent errors that might be hard to debug."
)
is_batched = bool(
isinstance(raw_speech, (list, tuple))
and (isinstance(raw_speech[0], np.ndarray) or isinstance(raw_speech[0], (tuple, list)))
)
if is_batched:
raw_speech = [np.asarray(speech, dtype=np.float32) for speech in raw_speech]
elif not is_batched and not isinstance(raw_speech, np.ndarray):
raw_speech = np.asarray(raw_speech, dtype=np.float32)
elif isinstance(raw_speech, np.ndarray) and raw_speech.dtype is np.dtype(np.float64):
raw_speech = raw_speech.astype(np.float32)
# always return batch
if not is_batched:
raw_speech = [raw_speech]
# extract fbank features
features = [self._extract_fbank_features(waveform) for waveform in raw_speech]
# convert into correct format for padding
encoded_inputs = BatchFeature({"input_features": features})
padded_inputs = self.pad(
encoded_inputs,
padding=padding,
max_length=max_length,
truncation=truncation,
pad_to_multiple_of=pad_to_multiple_of,
return_attention_mask=return_attention_mask,
**kwargs,
)
# make sure list is in array format
input_features = padded_inputs.get("input_features")
if isinstance(input_features[0], list):
padded_inputs["input_features"] = [np.asarray(feature, dtype=np.float32) for feature in input_features]
attention_mask = padded_inputs.get("attention_mask")
if attention_mask is not None:
padded_inputs["attention_mask"] = [np.asarray(array, dtype=np.int32) for array in attention_mask]
# Utterance-level cepstral mean and variance normalization
if self.do_ceptral_normalize:
attention_mask = (
np.array(attention_mask, dtype=np.int32)
if self._get_padding_strategies(padding, max_length=max_length) is not PaddingStrategy.DO_NOT_PAD
else None
)
padded_inputs["input_features"] = self.normalize(
padded_inputs["input_features"], attention_mask=attention_mask
)
if return_tensors is not None:
padded_inputs = padded_inputs.convert_to_tensors(return_tensors)
return padded_inputs