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from speaker_encoder.hparams import * | |
from speaker_encoder import audio | |
from pathlib import Path | |
from typing import Union, List | |
from torch import nn | |
from time import perf_counter as timer | |
import numpy as np | |
import torch | |
class SpeakerEncoder(nn.Module): | |
def __init__(self, weights_fpath, device: Union[str, torch.device]=None, verbose=True): | |
""" | |
:param device: either a torch device or the name of a torch device (e.g. "cpu", "cuda"). | |
If None, defaults to cuda if it is available on your machine, otherwise the model will | |
run on cpu. Outputs are always returned on the cpu, as numpy arrays. | |
""" | |
super().__init__() | |
# Define the network | |
self.lstm = nn.LSTM(mel_n_channels, model_hidden_size, model_num_layers, batch_first=True) | |
self.linear = nn.Linear(model_hidden_size, model_embedding_size) | |
self.relu = nn.ReLU() | |
# Get the target device | |
if device is None: | |
device = torch.device("cuda" if torch.cuda.is_available() else "cpu") | |
elif isinstance(device, str): | |
device = torch.device(device) | |
self.device = device | |
# Load the pretrained model'speaker weights | |
# weights_fpath = Path(__file__).resolve().parent.joinpath("pretrained.pt") | |
# if not weights_fpath.exists(): | |
# raise Exception("Couldn't find the voice encoder pretrained model at %s." % | |
# weights_fpath) | |
start = timer() | |
checkpoint = torch.load(weights_fpath, map_location="cpu") | |
self.load_state_dict(checkpoint["model_state"], strict=False) | |
self.to(device) | |
if verbose: | |
print("Loaded the voice encoder model on %s in %.2f seconds." % | |
(device.type, timer() - start)) | |
def forward(self, mels: torch.FloatTensor): | |
""" | |
Computes the embeddings of a batch of utterance spectrograms. | |
:param mels: a batch of mel spectrograms of same duration as a float32 tensor of shape | |
(batch_size, n_frames, n_channels) | |
:return: the embeddings as a float 32 tensor of shape (batch_size, embedding_size). | |
Embeddings are positive and L2-normed, thus they lay in the range [0, 1]. | |
""" | |
# Pass the input through the LSTM layers and retrieve the final hidden state of the last | |
# layer. Apply a cutoff to 0 for negative values and L2 normalize the embeddings. | |
_, (hidden, _) = self.lstm(mels) | |
embeds_raw = self.relu(self.linear(hidden[-1])) | |
return embeds_raw / torch.norm(embeds_raw, dim=1, keepdim=True) | |
def compute_partial_slices(n_samples: int, rate, min_coverage): | |
""" | |
Computes where to split an utterance waveform and its corresponding mel spectrogram to | |
obtain partial utterances of <partials_n_frames> each. Both the waveform and the | |
mel spectrogram slices are returned, so as to make each partial utterance waveform | |
correspond to its spectrogram. | |
The returned ranges may be indexing further than the length of the waveform. It is | |
recommended that you pad the waveform with zeros up to wav_slices[-1].stop. | |
:param n_samples: the number of samples in the waveform | |
:param rate: how many partial utterances should occur per second. Partial utterances must | |
cover the span of the entire utterance, thus the rate should not be lower than the inverse | |
of the duration of a partial utterance. By default, partial utterances are 1.6s long and | |
the minimum rate is thus 0.625. | |
:param min_coverage: when reaching the last partial utterance, it may or may not have | |
enough frames. If at least <min_pad_coverage> of <partials_n_frames> are present, | |
then the last partial utterance will be considered by zero-padding the audio. Otherwise, | |
it will be discarded. If there aren't enough frames for one partial utterance, | |
this parameter is ignored so that the function always returns at least one slice. | |
:return: the waveform slices and mel spectrogram slices as lists of array slices. Index | |
respectively the waveform and the mel spectrogram with these slices to obtain the partial | |
utterances. | |
""" | |
assert 0 < min_coverage <= 1 | |
# Compute how many frames separate two partial utterances | |
samples_per_frame = int((sampling_rate * mel_window_step / 1000)) | |
n_frames = int(np.ceil((n_samples + 1) / samples_per_frame)) | |
frame_step = int(np.round((sampling_rate / rate) / samples_per_frame)) | |
assert 0 < frame_step, "The rate is too high" | |
assert frame_step <= partials_n_frames, "The rate is too low, it should be %f at least" % \ | |
(sampling_rate / (samples_per_frame * partials_n_frames)) | |
# Compute the slices | |
wav_slices, mel_slices = [], [] | |
steps = max(1, n_frames - partials_n_frames + frame_step + 1) | |
for i in range(0, steps, frame_step): | |
mel_range = np.array([i, i + partials_n_frames]) | |
wav_range = mel_range * samples_per_frame | |
mel_slices.append(slice(*mel_range)) | |
wav_slices.append(slice(*wav_range)) | |
# Evaluate whether extra padding is warranted or not | |
last_wav_range = wav_slices[-1] | |
coverage = (n_samples - last_wav_range.start) / (last_wav_range.stop - last_wav_range.start) | |
if coverage < min_coverage and len(mel_slices) > 1: | |
mel_slices = mel_slices[:-1] | |
wav_slices = wav_slices[:-1] | |
return wav_slices, mel_slices | |
def embed_utterance(self, wav: np.ndarray, return_partials=False, rate=1.3, min_coverage=0.75): | |
""" | |
Computes an embedding for a single utterance. The utterance is divided in partial | |
utterances and an embedding is computed for each. The complete utterance embedding is the | |
L2-normed average embedding of the partial utterances. | |
TODO: independent batched version of this function | |
:param wav: a preprocessed utterance waveform as a numpy array of float32 | |
:param return_partials: if True, the partial embeddings will also be returned along with | |
the wav slices corresponding to each partial utterance. | |
:param rate: how many partial utterances should occur per second. Partial utterances must | |
cover the span of the entire utterance, thus the rate should not be lower than the inverse | |
of the duration of a partial utterance. By default, partial utterances are 1.6s long and | |
the minimum rate is thus 0.625. | |
:param min_coverage: when reaching the last partial utterance, it may or may not have | |
enough frames. If at least <min_pad_coverage> of <partials_n_frames> are present, | |
then the last partial utterance will be considered by zero-padding the audio. Otherwise, | |
it will be discarded. If there aren't enough frames for one partial utterance, | |
this parameter is ignored so that the function always returns at least one slice. | |
:return: the embedding as a numpy array of float32 of shape (model_embedding_size,). If | |
<return_partials> is True, the partial utterances as a numpy array of float32 of shape | |
(n_partials, model_embedding_size) and the wav partials as a list of slices will also be | |
returned. | |
""" | |
# Compute where to split the utterance into partials and pad the waveform with zeros if | |
# the partial utterances cover a larger range. | |
wav_slices, mel_slices = self.compute_partial_slices(len(wav), rate, min_coverage) | |
max_wave_length = wav_slices[-1].stop | |
if max_wave_length >= len(wav): | |
wav = np.pad(wav, (0, max_wave_length - len(wav)), "constant") | |
# Split the utterance into partials and forward them through the model | |
mel = audio.wav_to_mel_spectrogram(wav) | |
mels = np.array([mel[s] for s in mel_slices]) | |
with torch.no_grad(): | |
mels = torch.from_numpy(mels).to(self.device) | |
partial_embeds = self(mels).cpu().numpy() | |
# Compute the utterance embedding from the partial embeddings | |
raw_embed = np.mean(partial_embeds, axis=0) | |
embed = raw_embed / np.linalg.norm(raw_embed, 2) | |
if return_partials: | |
return embed, partial_embeds, wav_slices | |
return embed | |
def embed_speaker(self, wavs: List[np.ndarray], **kwargs): | |
""" | |
Compute the embedding of a collection of wavs (presumably from the same speaker) by | |
averaging their embedding and L2-normalizing it. | |
:param wavs: list of wavs a numpy arrays of float32. | |
:param kwargs: extra arguments to embed_utterance() | |
:return: the embedding as a numpy array of float32 of shape (model_embedding_size,). | |
""" | |
raw_embed = np.mean([self.embed_utterance(wav, return_partials=False, **kwargs) \ | |
for wav in wavs], axis=0) | |
return raw_embed / np.linalg.norm(raw_embed, 2) |