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# Copyright 2017 The TensorFlow Authors All Rights Reserved.
#
# 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.
# ==============================================================================
"""Compute input examples for VGGish from audio waveform."""
# Modification: Return torch tensors rather than numpy arrays
import torch
import torchaudio
import numpy as np
import mel_features
import vggish_params
def waveform_to_examples(data, sample_rate, return_tensor=True):
"""Converts audio waveform into an array of examples for VGGish.
Args:
data: np.array of either one dimension (mono) or two dimensions
(multi-channel, with the outer dimension representing channels).
Each sample is generally expected to lie in the range [-1.0, +1.0],
although this is not required.
sample_rate: Sample rate of data.
return_tensor: Return data as a Pytorch tensor ready for VGGish
Returns:
3-D np.array of shape [num_examples, num_frames, num_bands] which represents
a sequence of examples, each of which contains a patch of log mel
spectrogram, covering num_frames frames of audio and num_bands mel frequency
bands, where the frame length is vggish_params.STFT_HOP_LENGTH_SECONDS.
"""
if len(data.shape) > 1:
data = np.mean(data, axis=1)
# Resample to the rate assumed by VGGish.
if sample_rate != vggish_params.SAMPLE_RATE:
data = torch.from_numpy(data)
resampler = torchaudio.transforms.Resample(sample_rate, vggish_params.SAMPLE_RATE, dtype=data.dtype)
data = resampler(data).cpu().detach().numpy()
# Compute log mel spectrogram features.
log_mel = mel_features.log_mel_spectrogram(
data,
audio_sample_rate=vggish_params.SAMPLE_RATE,
log_offset=vggish_params.LOG_OFFSET,
window_length_secs=vggish_params.STFT_WINDOW_LENGTH_SECONDS,
hop_length_secs=vggish_params.STFT_HOP_LENGTH_SECONDS,
num_mel_bins=vggish_params.NUM_MEL_BINS,
lower_edge_hertz=vggish_params.MEL_MIN_HZ,
upper_edge_hertz=vggish_params.MEL_MAX_HZ)
# Frame features into examples.
features_sample_rate = 1.0 / vggish_params.STFT_HOP_LENGTH_SECONDS
example_window_length = int(round(
vggish_params.EXAMPLE_WINDOW_SECONDS * features_sample_rate))
example_hop_length = int(round(
vggish_params.EXAMPLE_HOP_SECONDS * features_sample_rate))
log_mel_examples = mel_features.frame(
log_mel,
window_length=example_window_length,
hop_length=example_hop_length)
if return_tensor:
log_mel_examples = torch.tensor(
log_mel_examples, requires_grad=True)[:, None, :, :].float()
return log_mel_examples