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PaddleSpeech/third_party/paddle_audio/frontend.py

147 lines
4.2 KiB

from typing import Tuple
import numpy as np
import paddle
from paddle import Tensor
from paddle import nn
from paddle.nn import functional as F
def frame(x: Tensor,
num_samples: Tensor,
win_length: int,
hop_length: int,
clip: bool = True) -> Tuple[Tensor, Tensor]:
"""Extract frames from audio.
Parameters
----------
x : Tensor
Shape (N, T), batched waveform.
num_samples : Tensor
Shape (N, ), number of samples of each waveform.
win_length : int
Window length.
hop_length : int
Number of samples shifted between ajancent frames.
clip : bool, optional
Whether to clip audio that does not fit into the last frame, by
default True
Returns
-------
frames : Tensor
Shape (N, T', win_length).
num_frames : Tensor
Shape (N, ) number of valid frames
"""
assert hop_length <= win_length
num_frames = (num_samples - win_length) // hop_length
padding = (0, 0)
if not clip:
num_frames += 1
# NOTE: pad hop_length - 1 to the right to ensure that there is at most
# one frame dangling to the righe edge
padding = (0, hop_length - 1)
weight = paddle.eye(win_length).unsqueeze(1)
frames = F.conv1d(x.unsqueeze(1),
weight,
padding=padding,
stride=(hop_length, ))
return frames, num_frames
class STFT(nn.Layer):
"""A module for computing stft transformation in a differentiable way.
Parameters
------------
n_fft : int
Number of samples in a frame.
hop_length : int
Number of samples shifted between adjacent frames.
win_length : int
Length of the window.
clip: bool
Whether to clip audio is necesaary.
"""
def __init__(self,
n_fft: int,
hop_length: int,
win_length: int,
window_type: str = None,
clip: bool = True):
super().__init__()
self.hop_length = hop_length
self.n_bin = 1 + n_fft // 2
self.n_fft = n_fft
self.clip = clip
# calculate window
if window_type is None:
window = np.ones(win_length)
elif window_type == "hann":
window = np.hanning(win_length)
elif window_type == "hamming":
window = np.hamming(win_length)
else:
raise ValueError("Not supported yet!")
if win_length < n_fft:
window = F.pad(window, (0, n_fft - win_length))
elif win_length > n_fft:
window = window[:n_fft]
# (n_bins, n_fft) complex
kernel_size = min(n_fft, win_length)
weight = np.fft.fft(np.eye(n_fft))[:self.n_bin, :kernel_size]
w_real = weight.real
w_imag = weight.imag
# (2 * n_bins, kernel_size)
w = np.concatenate([w_real, w_imag], axis=0)
w = w * window
# (2 * n_bins, 1, kernel_size) # (C_out, C_in, kernel_size)
w = np.expand_dims(w, 1)
weight = paddle.cast(paddle.to_tensor(w), paddle.get_default_dtype())
self.register_buffer("weight", weight)
def forward(self, x: Tensor, num_samples: Tensor) -> Tuple[Tensor, Tensor]:
"""Compute the stft transform.
Parameters
------------
x : Tensor [shape=(B, T)]
The input waveform.
num_samples : Tensor
Number of samples of each waveform.
Returns
------------
D : Tensor
Shape(N, T', n_bins, 2) Spectrogram.
num_frames: Tensor
Shape (N,) number of samples of each spectrogram
"""
num_frames = (num_samples - self.win_length) // self.hop_length
padding = (0, 0)
if not self.clip:
num_frames += 1
padding = (0, self.hop_length - 1)
batch_size, _, _ = paddle.shape(x)
x = x.unsqueeze(-1)
D = F.conv1d(self.weight,
x,
stride=(self.hop_length, ),
padding=padding,
data_format="NLC")
D = paddle.reshape(D, [batch_size, -1, self.n_bin, 2])
return D, num_frames