# Copyright (c) 2024 Alibaba Inc (authors: Xiang Lyu, Kai Hu)
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
# http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.
"""HIFI-GAN"""
import typing as tp
import numpy as np
from scipy.signal import get_window
import torch
import torch.nn as nn
import torch.nn.functional as F
from torch.nn import Conv1d
from torch.nn import ConvTranspose1d
from torch.nn.utils import remove_weight_norm
from torch.nn.utils import weight_norm
from torch.distributions.uniform import Uniform
from torch import sin
from torch.nn.parameter import Parameter
"""hifigan based generator implementation.
This code is modified from https://github.com/jik876/hifi-gan
,https://github.com/kan-bayashi/ParallelWaveGAN and
https://github.com/NVIDIA/BigVGAN
"""
class Snake(nn.Module):
'''
Implementation of a sine-based periodic activation function
Shape:
- Input: (B, C, T)
- Output: (B, C, T), same shape as the input
Parameters:
- alpha - trainable parameter
References:
- This activation function is from this paper by Liu Ziyin, Tilman Hartwig, Masahito Ueda:
https://arxiv.org/abs/2006.08195
Examples:
>>> a1 = snake(256)
>>> x = torch.randn(256)
>>> x = a1(x)
'''
def __init__(self, in_features, alpha=1.0, alpha_trainable=True, alpha_logscale=False):
'''
Initialization.
INPUT:
- in_features: shape of the input
- alpha: trainable parameter
alpha is initialized to 1 by default, higher values = higher-frequency.
alpha will be trained along with the rest of your model.
'''
super(Snake, self).__init__()
self.in_features = in_features
# initialize alpha
self.alpha_logscale = alpha_logscale
if self.alpha_logscale: # log scale alphas initialized to zeros
self.alpha = Parameter(torch.zeros(in_features) * alpha)
else: # linear scale alphas initialized to ones
self.alpha = Parameter(torch.ones(in_features) * alpha)
self.alpha.requires_grad = alpha_trainable
self.no_div_by_zero = 0.000000001
def forward(self, x):
'''
Forward pass of the function.
Applies the function to the input elementwise.
Snake ∶= x + 1/a * sin^2 (xa)
'''
alpha = self.alpha.unsqueeze(0).unsqueeze(-1) # line up with x to [B, C, T]
if self.alpha_logscale:
alpha = torch.exp(alpha)
x = x + (1.0 / (alpha + self.no_div_by_zero)) * pow(sin(x * alpha), 2)
return x
def get_padding(kernel_size, dilation=1):
return int((kernel_size * dilation - dilation) / 2)
def init_weights(m, mean=0.0, std=0.01):
classname = m.__class__.__name__
if classname.find("Conv") != -1:
m.weight.data.normal_(mean, std)
class ResBlock(torch.nn.Module):
"""Residual block module in HiFiGAN/BigVGAN."""
def __init__(
self,
channels: int = 512,
kernel_size: int = 3,
dilations: tp.List[int] = [1, 3, 5],
):
super(ResBlock, self).__init__()
self.convs1 = nn.ModuleList()
self.convs2 = nn.ModuleList()
for dilation in dilations:
self.convs1.append(
weight_norm(
Conv1d(
channels,
channels,
kernel_size,
1,
dilation=dilation,
padding=get_padding(kernel_size, dilation)
)
)
)
self.convs2.append(
weight_norm(
Conv1d(
channels,
channels,
kernel_size,
1,
dilation=1,
padding=get_padding(kernel_size, 1)
)
)
)
self.convs1.apply(init_weights)
self.convs2.apply(init_weights)
self.activations1 = nn.ModuleList([
Snake(channels, alpha_logscale=False)
for _ in range(len(self.convs1))
])
self.activations2 = nn.ModuleList([
Snake(channels, alpha_logscale=False)
for _ in range(len(self.convs2))
])
def forward(self, x: torch.Tensor) -> torch.Tensor:
for idx in range(len(self.convs1)):
xt = self.activations1[idx](x)
xt = self.convs1[idx](xt)
xt = self.activations2[idx](xt)
xt = self.convs2[idx](xt)
x = xt + x
return x
def remove_weight_norm(self):
for idx in range(len(self.convs1)):
remove_weight_norm(self.convs1[idx])
remove_weight_norm(self.convs2[idx])
class SineGen(torch.nn.Module):
""" Definition of sine generator
SineGen(samp_rate, harmonic_num = 0,
sine_amp = 0.1, noise_std = 0.003,
voiced_threshold = 0,
flag_for_pulse=False)
samp_rate: sampling rate in Hz
harmonic_num: number of harmonic overtones (default 0)
sine_amp: amplitude of sine-wavefrom (default 0.1)
noise_std: std of Gaussian noise (default 0.003)
voiced_thoreshold: F0 threshold for U/V classification (default 0)
flag_for_pulse: this SinGen is used inside PulseGen (default False)
Note: when flag_for_pulse is True, the first time step of a voiced
segment is always sin(np.pi) or cos(0)
"""
def __init__(self, samp_rate, harmonic_num=0,
sine_amp=0.1, noise_std=0.003,
voiced_threshold=0):
super(SineGen, self).__init__()
self.sine_amp = sine_amp
self.noise_std = noise_std
self.harmonic_num = harmonic_num
self.sampling_rate = samp_rate
self.voiced_threshold = voiced_threshold
def _f02uv(self, f0):
# generate uv signal
uv = (f0 > self.voiced_threshold).type(torch.float32)
return uv
@torch.no_grad()
def forward(self, f0):
"""
:param f0: [B, 1, sample_len], Hz
:return: [B, 1, sample_len]
"""
F_mat = torch.zeros((f0.size(0), self.harmonic_num + 1, f0.size(-1))).to(f0.device)
for i in range(self.harmonic_num + 1):
F_mat[:, i: i + 1, :] = f0 * (i + 1) / self.sampling_rate
theta_mat = 2 * np.pi * (torch.cumsum(F_mat, dim=-1) % 1)
u_dist = Uniform(low=-np.pi, high=np.pi)
phase_vec = u_dist.sample(sample_shape=(f0.size(0), self.harmonic_num + 1, 1)).to(F_mat.device)
phase_vec[:, 0, :] = 0
# generate sine waveforms
sine_waves = self.sine_amp * torch.sin(theta_mat + phase_vec)
# generate uv signal
uv = self._f02uv(f0)
# noise: for unvoiced should be similar to sine_amp
# std = self.sine_amp/3 -> max value ~ self.sine_amp
# . for voiced regions is self.noise_std
noise_amp = uv * self.noise_std + (1 - uv) * self.sine_amp / 3
noise = noise_amp * torch.randn_like(sine_waves)
# first: set the unvoiced part to 0 by uv
# then: additive noise
sine_waves = sine_waves * uv + noise
return sine_waves, uv, noise
class SourceModuleHnNSF(torch.nn.Module):
""" SourceModule for hn-nsf
SourceModule(sampling_rate, harmonic_num=0, sine_amp=0.1,
add_noise_std=0.003, voiced_threshod=0)
sampling_rate: sampling_rate in Hz
harmonic_num: number of harmonic above F0 (default: 0)
sine_amp: amplitude of sine source signal (default: 0.1)
add_noise_std: std of additive Gaussian noise (default: 0.003)
note that amplitude of noise in unvoiced is decided
by sine_amp
voiced_threshold: threhold to set U/V given F0 (default: 0)
Sine_source, noise_source = SourceModuleHnNSF(F0_sampled)
F0_sampled (batchsize, length, 1)
Sine_source (batchsize, length, 1)
noise_source (batchsize, length 1)
uv (batchsize, length, 1)
"""
def __init__(self, sampling_rate, upsample_scale, harmonic_num=0, sine_amp=0.1,
add_noise_std=0.003, voiced_threshod=0):
super(SourceModuleHnNSF, self).__init__()
self.sine_amp = sine_amp
self.noise_std = add_noise_std
# to produce sine waveforms
self.l_sin_gen = SineGen(sampling_rate, harmonic_num,
sine_amp, add_noise_std, voiced_threshod)
# to merge source harmonics into a single excitation
self.l_linear = torch.nn.Linear(harmonic_num + 1, 1)
self.l_tanh = torch.nn.Tanh()
def forward(self, x):
"""
Sine_source, noise_source = SourceModuleHnNSF(F0_sampled)
F0_sampled (batchsize, length, 1)
Sine_source (batchsize, length, 1)
noise_source (batchsize, length 1)
"""
# source for harmonic branch
with torch.no_grad():
sine_wavs, uv, _ = self.l_sin_gen(x.transpose(1, 2))
sine_wavs = sine_wavs.transpose(1, 2)
uv = uv.transpose(1, 2)
sine_merge = self.l_tanh(self.l_linear(sine_wavs))
# source for noise branch, in the same shape as uv
noise = torch.randn_like(uv) * self.sine_amp / 3
return sine_merge, noise, uv
class HiFTGenerator(nn.Module):
"""
HiFTNet Generator: Neural Source Filter + ISTFTNet
https://arxiv.org/abs/2309.09493
"""
def __init__(
self,
in_channels: int = 80,
base_channels: int = 512,
nb_harmonics: int = 8,
sampling_rate: int = 22050,
nsf_alpha: float = 0.1,
nsf_sigma: float = 0.003,
nsf_voiced_threshold: float = 10,
upsample_rates: tp.List[int] = [8, 8],
upsample_kernel_sizes: tp.List[int] = [16, 16],
istft_params: tp.Dict[str, int] = {"n_fft": 16, "hop_len": 4},
resblock_kernel_sizes: tp.List[int] = [3, 7, 11],
resblock_dilation_sizes: tp.List[tp.List[int]] = [[1, 3, 5], [1, 3, 5], [1, 3, 5]],
source_resblock_kernel_sizes: tp.List[int] = [7, 11],
source_resblock_dilation_sizes: tp.List[tp.List[int]] = [[1, 3, 5], [1, 3, 5]],
lrelu_slope: float = 0.1,
audio_limit: float = 0.99,
f0_predictor: torch.nn.Module = None,
):
super(HiFTGenerator, self).__init__()
self.out_channels = 1
self.nb_harmonics = nb_harmonics
self.sampling_rate = sampling_rate
self.istft_params = istft_params
self.lrelu_slope = lrelu_slope
self.audio_limit = audio_limit
self.num_kernels = len(resblock_kernel_sizes)
self.num_upsamples = len(upsample_rates)
self.m_source = SourceModuleHnNSF(
sampling_rate=sampling_rate,
upsample_scale=np.prod(upsample_rates) * istft_params["hop_len"],
harmonic_num=nb_harmonics,
sine_amp=nsf_alpha,
add_noise_std=nsf_sigma,
voiced_threshod=nsf_voiced_threshold)
self.f0_upsamp = torch.nn.Upsample(scale_factor=np.prod(upsample_rates) * istft_params["hop_len"])
self.conv_pre = weight_norm(
Conv1d(in_channels, base_channels, 7, 1, padding=3)
)
# Up
self.ups = nn.ModuleList()
for i, (u, k) in enumerate(zip(upsample_rates, upsample_kernel_sizes)):
self.ups.append(
weight_norm(
ConvTranspose1d(
base_channels // (2**i),
base_channels // (2**(i + 1)),
k,
u,
padding=(k - u) // 2,
)
)
)
# Down
self.source_downs = nn.ModuleList()
self.source_resblocks = nn.ModuleList()
downsample_rates = [1] + upsample_rates[::-1][:-1]
downsample_cum_rates = np.cumprod(downsample_rates)
for i, (u, k, d) in enumerate(zip(downsample_cum_rates[::-1], source_resblock_kernel_sizes,
source_resblock_dilation_sizes)):
if u == 1:
self.source_downs.append(
Conv1d(istft_params["n_fft"] + 2, base_channels // (2 ** (i + 1)), 1, 1)
)
else:
self.source_downs.append(
Conv1d(istft_params["n_fft"] + 2, base_channels // (2 ** (i + 1)), u * 2, u, padding=(u // 2))
)
self.source_resblocks.append(
ResBlock(base_channels // (2 ** (i + 1)), k, d)
)
self.resblocks = nn.ModuleList()
for i in range(len(self.ups)):
ch = base_channels // (2**(i + 1))
for j, (k, d) in enumerate(zip(resblock_kernel_sizes, resblock_dilation_sizes)):
self.resblocks.append(ResBlock(ch, k, d))
self.conv_post = weight_norm(Conv1d(ch, istft_params["n_fft"] + 2, 7, 1, padding=3))
self.ups.apply(init_weights)
self.conv_post.apply(init_weights)
self.reflection_pad = nn.ReflectionPad1d((1, 0))
self.stft_window = torch.from_numpy(get_window("hann", istft_params["n_fft"], fftbins=True).astype(np.float32))
self.f0_predictor = f0_predictor
def _f02source(self, f0: torch.Tensor) -> torch.Tensor:
f0 = self.f0_upsamp(f0[:, None]).transpose(1, 2) # bs,n,t
har_source, _, _ = self.m_source(f0)
return har_source.transpose(1, 2)
def _stft(self, x):
spec = torch.stft(
x,
self.istft_params["n_fft"], self.istft_params["hop_len"], self.istft_params["n_fft"], window=self.stft_window.to(x.device),
return_complex=True)
spec = torch.view_as_real(spec) # [B, F, TT, 2]
return spec[..., 0], spec[..., 1]
def _istft(self, magnitude, phase):
magnitude = torch.clip(magnitude, max=1e2)
real = magnitude * torch.cos(phase)
img = magnitude * torch.sin(phase)
inverse_transform = torch.istft(torch.complex(real, img), self.istft_params["n_fft"], self.istft_params["hop_len"], self.istft_params["n_fft"], window=self.stft_window.to(magnitude.device))
return inverse_transform
def forward(self, x: torch.Tensor, f0=None) -> torch.Tensor:
if f0 is None:
f0 = self.f0_predictor(x)
s = self._f02source(f0)
s_stft_real, s_stft_imag = self._stft(s.squeeze(1))
s_stft = torch.cat([s_stft_real, s_stft_imag], dim=1)
x = self.conv_pre(x)
for i in range(self.num_upsamples):
x = F.leaky_relu(x, self.lrelu_slope)
x = self.ups[i](x)
if i == self.num_upsamples - 1:
x = self.reflection_pad(x)
# fusion
si = self.source_downs[i](s_stft)
si = self.source_resblocks[i](si)
x = x + si
xs = None
for j in range(self.num_kernels):
if xs is None:
xs = self.resblocks[i * self.num_kernels + j](x)
else:
xs += self.resblocks[i * self.num_kernels + j](x)
x = xs / self.num_kernels
x = F.leaky_relu(x)
x = self.conv_post(x)
magnitude = torch.exp(x[:, :self.istft_params["n_fft"] // 2 + 1, :])
phase = torch.sin(x[:, self.istft_params["n_fft"] // 2 + 1:, :]) # actually, sin is redundancy
x = self._istft(magnitude, phase)
x = torch.clamp(x, -self.audio_limit, self.audio_limit)
return x
def remove_weight_norm(self):
print('Removing weight norm...')
for l in self.ups:
remove_weight_norm(l)
for l in self.resblocks:
l.remove_weight_norm()
remove_weight_norm(self.conv_pre)
remove_weight_norm(self.conv_post)
self.source_module.remove_weight_norm()
for l in self.source_downs:
remove_weight_norm(l)
for l in self.source_resblocks:
l.remove_weight_norm()
@torch.inference_mode()
def inference(self, mel: torch.Tensor, f0=None) -> torch.Tensor:
return self.forward(x=mel, f0=f0)