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# Copyright (c) Meta Platforms, Inc. and affiliates. | |
# All rights reserved. | |
# | |
# This source code is licensed under the license found in the | |
# LICENSE file in the root directory of this source tree. | |
# Adapted from MIT code under the original license | |
# Copyright 2019 Tomoki Hayashi | |
# MIT License (https://opensource.org/licenses/MIT) | |
import typing as tp | |
import torch | |
from torch import nn | |
from torch.nn import functional as F | |
# TODO: Replace with torchaudio.STFT? | |
def _stft(x: torch.Tensor, fft_size: int, hop_length: int, win_length: int, | |
window: tp.Optional[torch.Tensor], normalized: bool) -> torch.Tensor: | |
"""Perform STFT and convert to magnitude spectrogram. | |
Args: | |
x: Input signal tensor (B, C, T). | |
fft_size (int): FFT size. | |
hop_length (int): Hop size. | |
win_length (int): Window length. | |
window (torch.Tensor or None): Window function type. | |
normalized (bool): Whether to normalize the STFT or not. | |
Returns: | |
torch.Tensor: Magnitude spectrogram (B, C, #frames, fft_size // 2 + 1). | |
""" | |
B, C, T = x.shape | |
x_stft = torch.stft( | |
x.view(-1, T), fft_size, hop_length, win_length, window, | |
normalized=normalized, return_complex=True, | |
) | |
x_stft = x_stft.view(B, C, *x_stft.shape[1:]) | |
real = x_stft.real | |
imag = x_stft.imag | |
# 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(nn.Module): | |
"""Spectral convergence loss. | |
""" | |
def __init__(self, epsilon: float = torch.finfo(torch.float32).eps): | |
super().__init__() | |
self.epsilon = epsilon | |
def forward(self, x_mag: torch.Tensor, y_mag: torch.Tensor): | |
"""Calculate forward propagation. | |
Args: | |
x_mag: Magnitude spectrogram of predicted signal (B, #frames, #freq_bins). | |
y_mag: Magnitude spectrogram of groundtruth signal (B, #frames, #freq_bins). | |
Returns: | |
torch.Tensor: Spectral convergence loss value. | |
""" | |
return torch.norm(y_mag - x_mag, p="fro") / (torch.norm(y_mag, p="fro") + self.epsilon) | |
class LogSTFTMagnitudeLoss(nn.Module): | |
"""Log STFT magnitude loss. | |
Args: | |
epsilon (float): Epsilon value for numerical stability. | |
""" | |
def __init__(self, epsilon: float = torch.finfo(torch.float32).eps): | |
super().__init__() | |
self.epsilon = epsilon | |
def forward(self, x_mag: torch.Tensor, y_mag: torch.Tensor): | |
"""Calculate forward propagation. | |
Args: | |
x_mag (torch.Tensor): Magnitude spectrogram of predicted signal (B, #frames, #freq_bins). | |
y_mag (torch.Tensor): Magnitude spectrogram of groundtruth signal (B, #frames, #freq_bins). | |
Returns: | |
torch.Tensor: Log STFT magnitude loss value. | |
""" | |
return F.l1_loss(torch.log(self.epsilon + y_mag), torch.log(self.epsilon + x_mag)) | |
class STFTLosses(nn.Module): | |
"""STFT losses. | |
Args: | |
n_fft (int): Size of FFT. | |
hop_length (int): Hop length. | |
win_length (int): Window length. | |
window (str): Window function type. | |
normalized (bool): Whether to use normalized STFT or not. | |
epsilon (float): Epsilon for numerical stability. | |
""" | |
def __init__(self, n_fft: int = 1024, hop_length: int = 120, win_length: int = 600, | |
window: str = "hann_window", normalized: bool = False, | |
epsilon: float = torch.finfo(torch.float32).eps): | |
super().__init__() | |
self.n_fft = n_fft | |
self.hop_length = hop_length | |
self.win_length = win_length | |
self.normalized = normalized | |
self.register_buffer("window", getattr(torch, window)(win_length)) | |
self.spectral_convergenge_loss = SpectralConvergenceLoss(epsilon) | |
self.log_stft_magnitude_loss = LogSTFTMagnitudeLoss(epsilon) | |
def forward(self, x: torch.Tensor, y: torch.Tensor) -> tp.Tuple[torch.Tensor, torch.Tensor]: | |
"""Calculate forward propagation. | |
Args: | |
x (torch.Tensor): Predicted signal (B, T). | |
y (torch.Tensor): Groundtruth signal (B, T). | |
Returns: | |
torch.Tensor: Spectral convergence loss value. | |
torch.Tensor: Log STFT magnitude loss value. | |
""" | |
x_mag = _stft(x, self.n_fft, self.hop_length, | |
self.win_length, self.window, self.normalized) # type: ignore | |
y_mag = _stft(y, self.n_fft, self.hop_length, | |
self.win_length, self.window, self.normalized) # type: ignore | |
sc_loss = self.spectral_convergenge_loss(x_mag, y_mag) | |
mag_loss = self.log_stft_magnitude_loss(x_mag, y_mag) | |
return sc_loss, mag_loss | |
class STFTLoss(nn.Module): | |
"""Single Resolution STFT loss. | |
Args: | |
n_fft (int): Nb of FFT. | |
hop_length (int): Hop length. | |
win_length (int): Window length. | |
window (str): Window function type. | |
normalized (bool): Whether to use normalized STFT or not. | |
epsilon (float): Epsilon for numerical stability. | |
factor_sc (float): Coefficient for the spectral loss. | |
factor_mag (float): Coefficient for the magnitude loss. | |
""" | |
def __init__(self, n_fft: int = 1024, hop_length: int = 120, win_length: int = 600, | |
window: str = "hann_window", normalized: bool = False, | |
factor_sc: float = 0.1, factor_mag: float = 0.1, | |
epsilon: float = torch.finfo(torch.float32).eps): | |
super().__init__() | |
self.loss = STFTLosses(n_fft, hop_length, win_length, window, normalized, epsilon) | |
self.factor_sc = factor_sc | |
self.factor_mag = factor_mag | |
def forward(self, x: torch.Tensor, y: torch.Tensor) -> tp.Tuple[torch.Tensor, torch.Tensor]: | |
"""Calculate forward propagation. | |
Args: | |
x (torch.Tensor): Predicted signal (B, T). | |
y (torch.Tensor): Groundtruth signal (B, T). | |
Returns: | |
torch.Tensor: Single resolution STFT loss. | |
""" | |
sc_loss, mag_loss = self.loss(x, y) | |
return self.factor_sc * sc_loss + self.factor_mag * mag_loss | |
class MRSTFTLoss(nn.Module): | |
"""Multi resolution STFT loss. | |
Args: | |
n_ffts (Sequence[int]): Sequence of FFT sizes. | |
hop_lengths (Sequence[int]): Sequence of hop sizes. | |
win_lengths (Sequence[int]): Sequence of window lengths. | |
window (str): Window function type. | |
factor_sc (float): Coefficient for the spectral loss. | |
factor_mag (float): Coefficient for the magnitude loss. | |
normalized (bool): Whether to use normalized STFT or not. | |
epsilon (float): Epsilon for numerical stability. | |
""" | |
def __init__(self, n_ffts: tp.Sequence[int] = [1024, 2048, 512], hop_lengths: tp.Sequence[int] = [120, 240, 50], | |
win_lengths: tp.Sequence[int] = [600, 1200, 240], window: str = "hann_window", | |
factor_sc: float = 0.1, factor_mag: float = 0.1, | |
normalized: bool = False, epsilon: float = torch.finfo(torch.float32).eps): | |
super().__init__() | |
assert len(n_ffts) == len(hop_lengths) == len(win_lengths) | |
self.stft_losses = torch.nn.ModuleList() | |
for fs, ss, wl in zip(n_ffts, hop_lengths, win_lengths): | |
self.stft_losses += [STFTLosses(fs, ss, wl, window, normalized, epsilon)] | |
self.factor_sc = factor_sc | |
self.factor_mag = factor_mag | |
def forward(self, x: torch.Tensor, y: torch.Tensor) -> torch.Tensor: | |
"""Calculate forward propagation. | |
Args: | |
x (torch.Tensor): Predicted signal (B, T). | |
y (torch.Tensor): Groundtruth signal (B, T). | |
Returns: | |
torch.Tensor: Multi resolution STFT loss. | |
""" | |
sc_loss = torch.Tensor([0.0]) | |
mag_loss = torch.Tensor([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 /= len(self.stft_losses) | |
mag_loss /= len(self.stft_losses) | |
return self.factor_sc * sc_loss + self.factor_mag * mag_loss | |