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| import numpy as np | |
| import torch | |
| import torch.nn.functional as F | |
| from librosa.filters import mel | |
| class MelSpectrogram(torch.nn.Module): | |
| def __init__( | |
| self, | |
| n_mel_channels, | |
| sampling_rate, | |
| win_length, | |
| hop_length, | |
| n_fft=None, | |
| mel_fmin=0, | |
| mel_fmax=None, | |
| clamp = 1e-5 | |
| ): | |
| super().__init__() | |
| n_fft = win_length if n_fft is None else n_fft | |
| self.hann_window = {} | |
| mel_basis = mel( | |
| sr=sampling_rate, | |
| n_fft=n_fft, | |
| n_mels=n_mel_channels, | |
| fmin=mel_fmin, | |
| fmax=mel_fmax, | |
| htk=True) | |
| mel_basis = torch.from_numpy(mel_basis).float() | |
| self.register_buffer("mel_basis", mel_basis) | |
| self.n_fft = win_length if n_fft is None else n_fft | |
| self.hop_length = hop_length | |
| self.win_length = win_length | |
| self.sampling_rate = sampling_rate | |
| self.n_mel_channels = n_mel_channels | |
| self.clamp = clamp | |
| def forward(self, audio, keyshift=0, speed=1, center=True): | |
| factor = 2 ** (keyshift / 12) | |
| n_fft_new = int(np.round(self.n_fft * factor)) | |
| win_length_new = int(np.round(self.win_length * factor)) | |
| hop_length_new = int(np.round(self.hop_length * speed)) | |
| keyshift_key = str(keyshift)+'_'+str(audio.device) | |
| if keyshift_key not in self.hann_window: | |
| self.hann_window[keyshift_key] = torch.hann_window(win_length_new).to(audio.device) | |
| fft = torch.stft( | |
| audio, | |
| n_fft=n_fft_new, | |
| hop_length=hop_length_new, | |
| win_length=win_length_new, | |
| window=self.hann_window[keyshift_key], | |
| center=center, | |
| return_complex=True) | |
| magnitude = torch.sqrt(fft.real.pow(2) + fft.imag.pow(2)) | |
| if keyshift != 0: | |
| size = self.n_fft // 2 + 1 | |
| resize = magnitude.size(1) | |
| if resize < size: | |
| magnitude = F.pad(magnitude, (0, 0, 0, size-resize)) | |
| magnitude = magnitude[:, :size, :] * self.win_length / win_length_new | |
| mel_output = torch.matmul(self.mel_basis, magnitude) | |
| log_mel_spec = torch.log(torch.clamp(mel_output, min=self.clamp)) | |
| return log_mel_spec |