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# -*- coding: utf-8 -*-
"""Upsampling module.
This code is modified from https://github.com/r9y9/wavenet_vocoder.
"""
import numpy as np
import torch
import torch.nn.functional as F
from . import Conv1d
class Stretch2d(torch.nn.Module):
"""Stretch2d module."""
def __init__(self, x_scale, y_scale, mode="nearest"):
"""Initialize Stretch2d module.
Args:
x_scale (int): X scaling factor (Time axis in spectrogram).
y_scale (int): Y scaling factor (Frequency axis in spectrogram).
mode (str): Interpolation mode.
"""
super(Stretch2d, self).__init__()
self.x_scale = x_scale
self.y_scale = y_scale
self.mode = mode
def forward(self, x):
"""Calculate forward propagation.
Args:
x (Tensor): Input tensor (B, C, F, T).
Returns:
Tensor: Interpolated tensor (B, C, F * y_scale, T * x_scale),
"""
return F.interpolate(
x, scale_factor=(self.y_scale, self.x_scale), mode=self.mode)
class Conv2d(torch.nn.Conv2d):
"""Conv2d module with customized initialization."""
def __init__(self, *args, **kwargs):
"""Initialize Conv2d module."""
super(Conv2d, self).__init__(*args, **kwargs)
def reset_parameters(self):
"""Reset parameters."""
self.weight.data.fill_(1. / np.prod(self.kernel_size))
if self.bias is not None:
torch.nn.init.constant_(self.bias, 0.0)
class UpsampleNetwork(torch.nn.Module):
"""Upsampling network module."""
def __init__(self,
upsample_scales,
nonlinear_activation=None,
nonlinear_activation_params={},
interpolate_mode="nearest",
freq_axis_kernel_size=1,
use_causal_conv=False,
):
"""Initialize upsampling network module.
Args:
upsample_scales (list): List of upsampling scales.
nonlinear_activation (str): Activation function name.
nonlinear_activation_params (dict): Arguments for specified activation function.
interpolate_mode (str): Interpolation mode.
freq_axis_kernel_size (int): Kernel size in the direction of frequency axis.
"""
super(UpsampleNetwork, self).__init__()
self.use_causal_conv = use_causal_conv
self.up_layers = torch.nn.ModuleList()
for scale in upsample_scales:
# interpolation layer
stretch = Stretch2d(scale, 1, interpolate_mode)
self.up_layers += [stretch]
# conv layer
assert (freq_axis_kernel_size - 1) % 2 == 0, "Not support even number freq axis kernel size."
freq_axis_padding = (freq_axis_kernel_size - 1) // 2
kernel_size = (freq_axis_kernel_size, scale * 2 + 1)
if use_causal_conv:
padding = (freq_axis_padding, scale * 2)
else:
padding = (freq_axis_padding, scale)
conv = Conv2d(1, 1, kernel_size=kernel_size, padding=padding, bias=False)
self.up_layers += [conv]
# nonlinear
if nonlinear_activation is not None:
nonlinear = getattr(torch.nn, nonlinear_activation)(**nonlinear_activation_params)
self.up_layers += [nonlinear]
def forward(self, c):
"""Calculate forward propagation.
Args:
c : Input tensor (B, C, T).
Returns:
Tensor: Upsampled tensor (B, C, T'), where T' = T * prod(upsample_scales).
"""
c = c.unsqueeze(1) # (B, 1, C, T)
for f in self.up_layers:
if self.use_causal_conv and isinstance(f, Conv2d):
c = f(c)[..., :c.size(-1)]
else:
c = f(c)
return c.squeeze(1) # (B, C, T')
class ConvInUpsampleNetwork(torch.nn.Module):
"""Convolution + upsampling network module."""
def __init__(self,
upsample_scales,
nonlinear_activation=None,
nonlinear_activation_params={},
interpolate_mode="nearest",
freq_axis_kernel_size=1,
aux_channels=80,
aux_context_window=0,
use_causal_conv=False
):
"""Initialize convolution + upsampling network module.
Args:
upsample_scales (list): List of upsampling scales.
nonlinear_activation (str): Activation function name.
nonlinear_activation_params (dict): Arguments for specified activation function.
mode (str): Interpolation mode.
freq_axis_kernel_size (int): Kernel size in the direction of frequency axis.
aux_channels (int): Number of channels of pre-convolutional layer.
aux_context_window (int): Context window size of the pre-convolutional layer.
use_causal_conv (bool): Whether to use causal structure.
"""
super(ConvInUpsampleNetwork, self).__init__()
self.aux_context_window = aux_context_window
self.use_causal_conv = use_causal_conv and aux_context_window > 0
# To capture wide-context information in conditional features
kernel_size = aux_context_window + 1 if use_causal_conv else 2 * aux_context_window + 1
# NOTE(kan-bayashi): Here do not use padding because the input is already padded
self.conv_in = Conv1d(aux_channels, aux_channels, kernel_size=kernel_size, bias=False)
self.upsample = UpsampleNetwork(
upsample_scales=upsample_scales,
nonlinear_activation=nonlinear_activation,
nonlinear_activation_params=nonlinear_activation_params,
interpolate_mode=interpolate_mode,
freq_axis_kernel_size=freq_axis_kernel_size,
use_causal_conv=use_causal_conv,
)
def forward(self, c):
"""Calculate forward propagation.
Args:
c : Input tensor (B, C, T').
Returns:
Tensor: Upsampled tensor (B, C, T),
where T = (T' - aux_context_window * 2) * prod(upsample_scales).
Note:
The length of inputs considers the context window size.
"""
c_ = self.conv_in(c)
c = c_[:, :, :-self.aux_context_window] if self.use_causal_conv else c_
return self.upsample(c)