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# Adapted from https://github.com/kan-bayashi/ParallelWaveGAN | |
# Original Copyright 2019 Tomoki Hayashi | |
# MIT License (https://opensource.org/licenses/MIT) | |
"""STFT-based Loss modules.""" | |
import torch | |
import torch.nn.functional as F | |
from distutils.version import LooseVersion | |
is_pytorch_17plus = LooseVersion(torch.__version__) >= LooseVersion("1.7") | |
def stft(x, fft_size, hop_size, win_length, window): | |
"""Perform STFT and convert to magnitude spectrogram. | |
Args: | |
x (Tensor): Input signal tensor (B, T). | |
fft_size (int): FFT size. | |
hop_size (int): Hop size. | |
win_length (int): Window length. | |
window (str): Window function type. | |
Returns: | |
Tensor: Magnitude spectrogram (B, #frames, fft_size // 2 + 1). | |
""" | |
if is_pytorch_17plus: | |
x_stft = torch.stft( | |
x, fft_size, hop_size, win_length, window, return_complex=False | |
) | |
else: | |
x_stft = torch.stft(x, fft_size, hop_size, win_length, window) | |
real = x_stft[..., 0] | |
imag = x_stft[..., 1] | |
# NOTE(kan-bayashi): clamp is needed to avoid nan or inf | |
return torch.sqrt(torch.clamp(real**2 + imag**2, min=1e-7)).transpose(2, 1) | |
class SpectralConvergenceLoss(torch.nn.Module): | |
"""Spectral convergence loss module.""" | |
def __init__(self): | |
"""Initilize spectral convergence loss module.""" | |
super(SpectralConvergenceLoss, self).__init__() | |
def forward(self, x_mag, y_mag): | |
"""Calculate forward propagation. | |
Args: | |
x_mag (Tensor): Magnitude spectrogram of predicted signal (B, #frames, #freq_bins). | |
y_mag (Tensor): Magnitude spectrogram of groundtruth signal (B, #frames, #freq_bins). | |
Returns: | |
Tensor: Spectral convergence loss value. | |
""" | |
return torch.norm(y_mag - x_mag, p="fro") / torch.norm(y_mag, p="fro") | |
class LogSTFTMagnitudeLoss(torch.nn.Module): | |
"""Log STFT magnitude loss module.""" | |
def __init__(self): | |
"""Initilize los STFT magnitude loss module.""" | |
super(LogSTFTMagnitudeLoss, self).__init__() | |
def forward(self, x_mag, y_mag): | |
"""Calculate forward propagation. | |
Args: | |
x_mag (Tensor): Magnitude spectrogram of predicted signal (B, #frames, #freq_bins). | |
y_mag (Tensor): Magnitude spectrogram of groundtruth signal (B, #frames, #freq_bins). | |
Returns: | |
Tensor: Log STFT magnitude loss value. | |
""" | |
return F.l1_loss(torch.log(y_mag), torch.log(x_mag)) | |
class STFTLoss(torch.nn.Module): | |
"""STFT loss module.""" | |
def __init__( | |
self, fft_size=1024, shift_size=120, win_length=600, window="hann_window", | |
band="full" | |
): | |
"""Initialize STFT loss module.""" | |
super(STFTLoss, self).__init__() | |
self.fft_size = fft_size | |
self.shift_size = shift_size | |
self.win_length = win_length | |
self.band = band | |
self.spectral_convergence_loss = SpectralConvergenceLoss() | |
self.log_stft_magnitude_loss = LogSTFTMagnitudeLoss() | |
# NOTE(kan-bayashi): Use register_buffer to fix #223 | |
self.register_buffer("window", getattr(torch, window)(win_length)) | |
def forward(self, x, y): | |
"""Calculate forward propagation. | |
Args: | |
x (Tensor): Predicted signal (B, T). | |
y (Tensor): Groundtruth signal (B, T). | |
Returns: | |
Tensor: Spectral convergence loss value. | |
Tensor: Log STFT magnitude loss value. | |
""" | |
x_mag = stft(x, self.fft_size, self.shift_size, self.win_length, self.window) | |
y_mag = stft(y, self.fft_size, self.shift_size, self.win_length, self.window) | |
if self.band == "high": | |
freq_mask_ind = x_mag.shape[1] // 2 # only select high frequency bands | |
sc_loss = self.spectral_convergence_loss(x_mag[:,freq_mask_ind:,:], y_mag[:,freq_mask_ind:,:]) | |
mag_loss = self.log_stft_magnitude_loss(x_mag[:,freq_mask_ind:,:], y_mag[:,freq_mask_ind:,:]) | |
elif self.band == "full": | |
sc_loss = self.spectral_convergence_loss(x_mag, y_mag) | |
mag_loss = self.log_stft_magnitude_loss(x_mag, y_mag) | |
else: | |
raise NotImplementedError | |
return sc_loss, mag_loss | |
class MultiResolutionSTFTLoss(torch.nn.Module): | |
"""Multi resolution STFT loss module.""" | |
def __init__( | |
self, fft_sizes=[1024, 2048, 512], hop_sizes=[120, 240, 50], win_lengths=[600, 1200, 240], | |
window="hann_window", sc_lambda=0.1, mag_lambda=0.1, band="full" | |
): | |
"""Initialize Multi resolution STFT loss module. | |
Args: | |
fft_sizes (list): List of FFT sizes. | |
hop_sizes (list): List of hop sizes. | |
win_lengths (list): List of window lengths. | |
window (str): Window function type. | |
*_lambda (float): a balancing factor across different losses. | |
band (str): high-band or full-band loss | |
""" | |
super(MultiResolutionSTFTLoss, self).__init__() | |
self.sc_lambda = sc_lambda | |
self.mag_lambda = mag_lambda | |
assert len(fft_sizes) == len(hop_sizes) == len(win_lengths) | |
self.stft_losses = torch.nn.ModuleList() | |
for fs, ss, wl in zip(fft_sizes, hop_sizes, win_lengths): | |
self.stft_losses += [STFTLoss(fs, ss, wl, window, band)] | |
def forward(self, x, y): | |
"""Calculate forward propagation. | |
Args: | |
x (Tensor): Predicted signal (B, T) or (B, #subband, T). | |
y (Tensor): Groundtruth signal (B, T) or (B, #subband, T). | |
Returns: | |
Tensor: Multi resolution spectral convergence loss value. | |
Tensor: Multi resolution log STFT magnitude loss value. | |
""" | |
if len(x.shape) == 3: | |
x = x.view(-1, x.size(2)) # (B, C, T) -> (B x C, T) | |
y = y.view(-1, y.size(2)) # (B, C, T) -> (B x C, T) | |
sc_loss = 0.0 | |
mag_loss = 0.0 | |
for f in self.stft_losses: | |
sc_l, mag_l = f(x, y) | |
sc_loss += sc_l | |
mag_loss += mag_l | |
sc_loss *= self.sc_lambda | |
sc_loss /= len(self.stft_losses) | |
mag_loss *= self.mag_lambda | |
mag_loss /= len(self.stft_losses) | |
return sc_loss, mag_loss |