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| import torch | |
| import torchaudio.functional as F | |
| from torch import Tensor, nn | |
| from torchaudio.transforms import MelScale | |
| class LinearSpectrogram(nn.Module): | |
| def __init__( | |
| self, | |
| n_fft=2048, | |
| win_length=2048, | |
| hop_length=512, | |
| center=False, | |
| mode="pow2_sqrt", | |
| ): | |
| super().__init__() | |
| self.n_fft = n_fft | |
| self.win_length = win_length | |
| self.hop_length = hop_length | |
| self.center = center | |
| self.mode = mode | |
| self.register_buffer("window", torch.hann_window(win_length), persistent=False) | |
| def forward(self, y: Tensor) -> Tensor: | |
| if y.ndim == 3: | |
| y = y.squeeze(1) | |
| y = torch.nn.functional.pad( | |
| y.unsqueeze(1), | |
| ( | |
| (self.win_length - self.hop_length) // 2, | |
| (self.win_length - self.hop_length + 1) // 2, | |
| ), | |
| mode="reflect", | |
| ).squeeze(1) | |
| spec = torch.stft( | |
| y, | |
| self.n_fft, | |
| hop_length=self.hop_length, | |
| win_length=self.win_length, | |
| window=self.window, | |
| center=self.center, | |
| pad_mode="reflect", | |
| normalized=False, | |
| onesided=True, | |
| return_complex=True, | |
| ) | |
| spec = torch.view_as_real(spec) | |
| if self.mode == "pow2_sqrt": | |
| spec = torch.sqrt(spec.pow(2).sum(-1) + 1e-6) | |
| return spec | |
| class LogMelSpectrogram(nn.Module): | |
| def __init__( | |
| self, | |
| sample_rate=44100, | |
| n_fft=2048, | |
| win_length=2048, | |
| hop_length=512, | |
| n_mels=128, | |
| center=False, | |
| f_min=0.0, | |
| f_max=None, | |
| ): | |
| super().__init__() | |
| self.sample_rate = sample_rate | |
| self.n_fft = n_fft | |
| self.win_length = win_length | |
| self.hop_length = hop_length | |
| self.center = center | |
| self.n_mels = n_mels | |
| self.f_min = f_min | |
| self.f_max = f_max or float(sample_rate // 2) | |
| self.spectrogram = LinearSpectrogram(n_fft, win_length, hop_length, center) | |
| fb = F.melscale_fbanks( | |
| n_freqs=self.n_fft // 2 + 1, | |
| f_min=self.f_min, | |
| f_max=self.f_max, | |
| n_mels=self.n_mels, | |
| sample_rate=self.sample_rate, | |
| norm="slaney", | |
| mel_scale="slaney", | |
| ) | |
| self.register_buffer( | |
| "fb", | |
| fb, | |
| persistent=False, | |
| ) | |
| def compress(self, x: Tensor) -> Tensor: | |
| return torch.log(torch.clamp(x, min=1e-5)) | |
| def decompress(self, x: Tensor) -> Tensor: | |
| return torch.exp(x) | |
| def apply_mel_scale(self, x: Tensor) -> Tensor: | |
| return torch.matmul(x.transpose(-1, -2), self.fb).transpose(-1, -2) | |
| def forward( | |
| self, x: Tensor, return_linear: bool = False, sample_rate: int = None | |
| ) -> Tensor: | |
| if sample_rate is not None and sample_rate != self.sample_rate: | |
| x = F.resample(x, orig_freq=sample_rate, new_freq=self.sample_rate) | |
| linear = self.spectrogram(x) | |
| x = self.apply_mel_scale(linear) | |
| x = self.compress(x) | |
| if return_linear: | |
| return x, self.compress(linear) | |
| return x | |