mirror of
https://github.com/mozilla/DeepSpeech.git
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65 lines
2.3 KiB
Python
65 lines
2.3 KiB
Python
from __future__ import absolute_import, print_function
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import scipy.io.wavfile as wav
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import sys
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import math
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import warnings
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class DeepSpeechDeprecationWarning(DeprecationWarning):
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pass
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warnings.simplefilter('once', category=DeepSpeechDeprecationWarning)
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try:
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from deepspeech import audioToInputVector
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except ImportError:
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warnings.warn('DeepSpeech Python bindings could not be imported, resorting to slower code to compute audio features. '
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'Refer to README.md for instructions on how to install (or build) the DeepSpeech Python bindings.',
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category=DeepSpeechDeprecationWarning)
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import numpy as np
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from python_speech_features import mfcc
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from six.moves import range
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def audioToInputVector(audio, fs, numcep, numcontext):
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# Get mfcc coefficients
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features = mfcc(audio, samplerate=fs, numcep=numcep)
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# We only keep every second feature (BiRNN stride = 2)
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features = features[::2]
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# One stride per time step in the input
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num_strides = len(features)
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# Add empty initial and final contexts
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empty_context = np.zeros((numcontext, numcep), dtype=features.dtype)
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features = np.concatenate((empty_context, features, empty_context))
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# Create a view into the array with overlapping strides of size
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# numcontext (past) + 1 (present) + numcontext (future)
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window_size = 2*numcontext+1
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train_inputs = np.lib.stride_tricks.as_strided(
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features,
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(num_strides, window_size, numcep),
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(features.strides[0], features.strides[0], features.strides[1]),
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writeable=False)
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# Flatten the second and third dimensions
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train_inputs = np.reshape(train_inputs, [num_strides, -1])
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# Return results
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return train_inputs
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def audiofile_to_input_vector(audio_filename, numcep, numcontext):
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r"""
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Given a WAV audio file at ``audio_filename``, calculates ``numcep`` MFCC features
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at every 0.01s time step with a window length of 0.025s. Appends ``numcontext``
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context frames to the left and right of each time step, and returns this data
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in a numpy array.
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"""
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# Load wav files
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fs, audio = wav.read(audio_filename)
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return audioToInputVector(audio, fs, numcep, numcontext)
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