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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. | |
| import typing as tp | |
| from einops import rearrange | |
| from librosa import filters | |
| import torch | |
| from torch import nn | |
| import torch.nn.functional as F | |
| import torchaudio | |
| class ChromaExtractor(nn.Module): | |
| """Chroma extraction and quantization. | |
| Args: | |
| sample_rate (int): Sample rate for the chroma extraction. | |
| n_chroma (int): Number of chroma bins for the chroma extraction. | |
| radix2_exp (int): Size of stft window for the chroma extraction (power of 2, e.g. 12 -> 2^12). | |
| nfft (int, optional): Number of FFT. | |
| winlen (int, optional): Window length. | |
| winhop (int, optional): Window hop size. | |
| argmax (bool, optional): Whether to use argmax. Defaults to False. | |
| norm (float, optional): Norm for chroma normalization. Defaults to inf. | |
| """ | |
| def __init__(self, sample_rate: int, n_chroma: int = 12, radix2_exp: int = 12, nfft: tp.Optional[int] = None, | |
| winlen: tp.Optional[int] = None, winhop: tp.Optional[int] = None, argmax: bool = False, | |
| norm: float = torch.inf): | |
| super().__init__() | |
| self.winlen = winlen or 2 ** radix2_exp | |
| self.nfft = nfft or self.winlen | |
| self.winhop = winhop or (self.winlen // 4) | |
| self.sample_rate = sample_rate | |
| self.n_chroma = n_chroma | |
| self.norm = norm | |
| self.argmax = argmax | |
| self.register_buffer('fbanks', torch.from_numpy(filters.chroma(sr=sample_rate, n_fft=self.nfft, tuning=0, | |
| n_chroma=self.n_chroma)), persistent=False) | |
| self.spec = torchaudio.transforms.Spectrogram(n_fft=self.nfft, win_length=self.winlen, | |
| hop_length=self.winhop, power=2, center=True, | |
| pad=0, normalized=True) | |
| def forward(self, wav: torch.Tensor) -> torch.Tensor: | |
| T = wav.shape[-1] | |
| # in case we are getting a wav that was dropped out (nullified) | |
| # from the conditioner, make sure wav length is no less that nfft | |
| if T < self.nfft: | |
| pad = self.nfft - T | |
| r = 0 if pad % 2 == 0 else 1 | |
| wav = F.pad(wav, (pad // 2, pad // 2 + r), 'constant', 0) | |
| assert wav.shape[-1] == self.nfft, f"expected len {self.nfft} but got {wav.shape[-1]}" | |
| spec = self.spec(wav).squeeze(1) | |
| raw_chroma = torch.einsum('cf,...ft->...ct', self.fbanks, spec) | |
| norm_chroma = torch.nn.functional.normalize(raw_chroma, p=self.norm, dim=-2, eps=1e-6) | |
| norm_chroma = rearrange(norm_chroma, 'b d t -> b t d') | |
| if self.argmax: | |
| idx = norm_chroma.argmax(-1, keepdim=True) | |
| norm_chroma[:] = 0 | |
| norm_chroma.scatter_(dim=-1, index=idx, value=1) | |
| return norm_chroma | |