基于 MelGAN 的特征匹配声谱反演
作者： Darshan Deshpande
创建时间 02/09/2021
上次修改时间 15/09/2021
描述：使用 MelGAN 架构和特征匹配进行音频从梅尔声谱图的反演。
引言
自回归声码器在语音处理的大部分历史中一直很普遍，但在其存在的大部分时间里，它们都缺乏并行性。MelGAN 是一种非自回归的全卷积声码器架构，用于从频谱反演和语音增强到当今最先进的语音合成（当用作 Tacotron2 或 FastSpeech 等将文本转换为梅尔声谱图的模型的解码器时）。
在本教程中，我们将了解 MelGAN 架构以及它如何实现快速频谱反演，即声谱图到音频波形的转换。本教程中实现的 MelGAN 与原始实现类似，唯一的区别是卷积填充方法，我们将使用“same”而不是反射填充。
导入和定义超参数
!pip install -qqq tensorflow_addons
!pip install -qqq tensorflow-io
import tensorflow as tf
import tensorflow_io as tfio
from tensorflow import keras
from tensorflow.keras import layers
from tensorflow_addons import layers as addon_layers
# Setting logger level to avoid input shape warnings
tf.get_logger().setLevel("ERROR")
# Defining hyperparameters
DESIRED_SAMPLES = 8192
LEARNING_RATE_GEN = 1e-5
LEARNING_RATE_DISC = 1e-6
BATCH_SIZE = 16
mse = keras.losses.MeanSquaredError()
mae = keras.losses.MeanAbsoluteError()
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加载数据集
此示例使用 LJSpeech 数据集。
LJSpeech 数据集主要用于文本到语音，包含从 7 本非虚构书籍中提取的 13,100 个离散语音样本，总时长约为 24 小时。MelGAN 训练仅关注音频波形，因此我们仅处理 WAV 文件并忽略音频注释。
!wget https://data.keithito.com/data/speech/LJSpeech-1.1.tar.bz2
!tar -xf /content/LJSpeech-1.1.tar.bz2
--2021-09-16 11:45:24-- https://data.keithito.com/data/speech/LJSpeech-1.1.tar.bz2
Resolving data.keithito.com (data.keithito.com)... 174.138.79.61
Connecting to data.keithito.com (data.keithito.com)|174.138.79.61|:443... connected.
HTTP request sent, awaiting response... 200 OK
Length: 2748572632 (2.6G) [application/octet-stream]
Saving to: ‘LJSpeech-1.1.tar.bz2’
LJSpeech-1.1.tar.bz 100%[===================>] 2.56G 68.3MB/s in 36s
2021-09-16 11:46:01 (72.2 MB/s) - ‘LJSpeech-1.1.tar.bz2’ saved [2748572632/2748572632]
我们创建一个 tf.data.Dataset 以动态加载和处理音频文件。preprocess() 函数以文件路径作为输入，并返回两个波形实例，一个用于输入，另一个作为比较的真实值。输入波形将使用自定义 MelSpec 层映射到声谱图，如本示例后面所示。
# Splitting the dataset into training and testing splits
wavs = tf.io.gfile.glob("LJSpeech-1.1/wavs/*.wav")
print(f"Number of audio files: {len(wavs)}")
# Mapper function for loading the audio. This function returns two instances of the wave
def preprocess(filename):
audio = tf.audio.decode_wav(tf.io.read_file(filename), 1, DESIRED_SAMPLES).audio
return audio, audio
# Create tf.data.Dataset objects and apply preprocessing
train_dataset = tf.data.Dataset.from_tensor_slices((wavs,))
train_dataset = train_dataset.map(preprocess, num_parallel_calls=tf.data.AUTOTUNE)
Number of audio files: 13100
为 MelGAN 定义自定义层
MelGAN 架构包含 3 个主要模块
- 残差块
- 扩张卷积块
- 判别器块
由于网络以梅尔声谱图作为输入，因此我们将创建一个额外的自定义层，可以动态地将原始音频波形转换为声谱图。我们使用来自 train_dataset 的原始音频张量，并使用下面的 MelSpec 层将其映射到梅尔声谱图。
# Custom keras layer for on-the-fly audio to spectrogram conversion
class MelSpec(layers.Layer):
def __init__(
self,
frame_length=1024,
frame_step=256,
fft_length=None,
sampling_rate=22050,
num_mel_channels=80,
freq_min=125,
freq_max=7600,
**kwargs,
):
super().__init__(**kwargs)
self.frame_length = frame_length
self.frame_step = frame_step
self.fft_length = fft_length
self.sampling_rate = sampling_rate
self.num_mel_channels = num_mel_channels
self.freq_min = freq_min
self.freq_max = freq_max
# Defining mel filter. This filter will be multiplied with the STFT output
self.mel_filterbank = tf.signal.linear_to_mel_weight_matrix(
num_mel_bins=self.num_mel_channels,
num_spectrogram_bins=self.frame_length // 2 + 1,
sample_rate=self.sampling_rate,
lower_edge_hertz=self.freq_min,
upper_edge_hertz=self.freq_max,
)
def call(self, audio, training=True):
# We will only perform the transformation during training.
if training:
# Taking the Short Time Fourier Transform. Ensure that the audio is padded.
# In the paper, the STFT output is padded using the 'REFLECT' strategy.
stft = tf.signal.stft(
tf.squeeze(audio, -1),
self.frame_length,
self.frame_step,
self.fft_length,
pad_end=True,
)
# Taking the magnitude of the STFT output
magnitude = tf.abs(stft)
# Multiplying the Mel-filterbank with the magnitude and scaling it using the db scale
mel = tf.matmul(tf.square(magnitude), self.mel_filterbank)
log_mel_spec = tfio.audio.dbscale(mel, top_db=80)
return log_mel_spec
else:
return audio
def get_config(self):
config = super().get_config()
config.update(
{
"frame_length": self.frame_length,
"frame_step": self.frame_step,
"fft_length": self.fft_length,
"sampling_rate": self.sampling_rate,
"num_mel_channels": self.num_mel_channels,
"freq_min": self.freq_min,
"freq_max": self.freq_max,
}
)
return config
残差卷积块广泛使用扩张卷积，每个块的总感受野为 27 个时间步长。为了确保减少输出中的嘶嘶声，扩张卷积必须以 kernel_size 的幂增长。论文中提出的网络如下
# Creating the residual stack block
def residual_stack(input, filters):
"""Convolutional residual stack with weight normalization.
Args:
filters: int, determines filter size for the residual stack.
Returns:
Residual stack output.
"""
c1 = addon_layers.WeightNormalization(
layers.Conv1D(filters, 3, dilation_rate=1, padding="same"), data_init=False
)(input)
lrelu1 = layers.LeakyReLU()(c1)
c2 = addon_layers.WeightNormalization(
layers.Conv1D(filters, 3, dilation_rate=1, padding="same"), data_init=False
)(lrelu1)
add1 = layers.Add()([c2, input])
lrelu2 = layers.LeakyReLU()(add1)
c3 = addon_layers.WeightNormalization(
layers.Conv1D(filters, 3, dilation_rate=3, padding="same"), data_init=False
)(lrelu2)
lrelu3 = layers.LeakyReLU()(c3)
c4 = addon_layers.WeightNormalization(
layers.Conv1D(filters, 3, dilation_rate=1, padding="same"), data_init=False
)(lrelu3)
add2 = layers.Add()([add1, c4])
lrelu4 = layers.LeakyReLU()(add2)
c5 = addon_layers.WeightNormalization(
layers.Conv1D(filters, 3, dilation_rate=9, padding="same"), data_init=False
)(lrelu4)
lrelu5 = layers.LeakyReLU()(c5)
c6 = addon_layers.WeightNormalization(
layers.Conv1D(filters, 3, dilation_rate=1, padding="same"), data_init=False
)(lrelu5)
add3 = layers.Add()([c6, add2])
return add3
每个卷积块使用残差堆栈提供的扩张卷积，并通过 upsampling_factor 对输入数据进行上采样。
# Dilated convolutional block consisting of the Residual stack
def conv_block(input, conv_dim, upsampling_factor):
"""Dilated Convolutional Block with weight normalization.
Args:
conv_dim: int, determines filter size for the block.
upsampling_factor: int, scale for upsampling.
Returns:
Dilated convolution block.
"""
conv_t = addon_layers.WeightNormalization(
layers.Conv1DTranspose(conv_dim, 16, upsampling_factor, padding="same"),
data_init=False,
)(input)
lrelu1 = layers.LeakyReLU()(conv_t)
res_stack = residual_stack(lrelu1, conv_dim)
lrelu2 = layers.LeakyReLU()(res_stack)
return lrelu2
判别器块包含卷积和下采样层。此块对于特征匹配技术的实现至关重要。
每个判别器输出一系列特征图，这些特征图将在训练期间进行比较以计算特征匹配损失。
def discriminator_block(input):
conv1 = addon_layers.WeightNormalization(
layers.Conv1D(16, 15, 1, "same"), data_init=False
)(input)
lrelu1 = layers.LeakyReLU()(conv1)
conv2 = addon_layers.WeightNormalization(
layers.Conv1D(64, 41, 4, "same", groups=4), data_init=False
)(lrelu1)
lrelu2 = layers.LeakyReLU()(conv2)
conv3 = addon_layers.WeightNormalization(
layers.Conv1D(256, 41, 4, "same", groups=16), data_init=False
)(lrelu2)
lrelu3 = layers.LeakyReLU()(conv3)
conv4 = addon_layers.WeightNormalization(
layers.Conv1D(1024, 41, 4, "same", groups=64), data_init=False
)(lrelu3)
lrelu4 = layers.LeakyReLU()(conv4)
conv5 = addon_layers.WeightNormalization(
layers.Conv1D(1024, 41, 4, "same", groups=256), data_init=False
)(lrelu4)
lrelu5 = layers.LeakyReLU()(conv5)
conv6 = addon_layers.WeightNormalization(
layers.Conv1D(1024, 5, 1, "same"), data_init=False
)(lrelu5)
lrelu6 = layers.LeakyReLU()(conv6)
conv7 = addon_layers.WeightNormalization(
layers.Conv1D(1, 3, 1, "same"), data_init=False
)(lrelu6)
return [lrelu1, lrelu2, lrelu3, lrelu4, lrelu5, lrelu6, conv7]
创建生成器
def create_generator(input_shape):
inp = keras.Input(input_shape)
x = MelSpec()(inp)
x = layers.Conv1D(512, 7, padding="same")(x)
x = layers.LeakyReLU()(x)
x = conv_block(x, 256, 8)
x = conv_block(x, 128, 8)
x = conv_block(x, 64, 2)
x = conv_block(x, 32, 2)
x = addon_layers.WeightNormalization(
layers.Conv1D(1, 7, padding="same", activation="tanh")
)(x)
return keras.Model(inp, x)
# We use a dynamic input shape for the generator since the model is fully convolutional
generator = create_generator((None, 1))
generator.summary()
Model: "model"
__________________________________________________________________________________________________
Layer (type) Output Shape Param # Connected to
==================================================================================================
input_1 (InputLayer) [(None, None, 1)] 0
__________________________________________________________________________________________________
mel_spec (MelSpec) (None, None, 80) 0 input_1[0][0]
__________________________________________________________________________________________________
conv1d (Conv1D) (None, None, 512) 287232 mel_spec[0][0]
__________________________________________________________________________________________________
leaky_re_lu (LeakyReLU) (None, None, 512) 0 conv1d[0][0]
__________________________________________________________________________________________________
weight_normalization (WeightNor (None, None, 256) 2097921 leaky_re_lu[0][0]
__________________________________________________________________________________________________
leaky_re_lu_1 (LeakyReLU) (None, None, 256) 0 weight_normalization[0][0]
__________________________________________________________________________________________________
weight_normalization_1 (WeightN (None, None, 256) 197121 leaky_re_lu_1[0][0]
__________________________________________________________________________________________________
leaky_re_lu_2 (LeakyReLU) (None, None, 256) 0 weight_normalization_1[0][0]
__________________________________________________________________________________________________
weight_normalization_2 (WeightN (None, None, 256) 197121 leaky_re_lu_2[0][0]
__________________________________________________________________________________________________
add (Add) (None, None, 256) 0 weight_normalization_2[0][0]
leaky_re_lu_1[0][0]
__________________________________________________________________________________________________
leaky_re_lu_3 (LeakyReLU) (None, None, 256) 0 add[0][0]
__________________________________________________________________________________________________
weight_normalization_3 (WeightN (None, None, 256) 197121 leaky_re_lu_3[0][0]
__________________________________________________________________________________________________
leaky_re_lu_4 (LeakyReLU) (None, None, 256) 0 weight_normalization_3[0][0]
__________________________________________________________________________________________________
weight_normalization_4 (WeightN (None, None, 256) 197121 leaky_re_lu_4[0][0]
__________________________________________________________________________________________________
add_1 (Add) (None, None, 256) 0 add[0][0]
weight_normalization_4[0][0]
__________________________________________________________________________________________________
leaky_re_lu_5 (LeakyReLU) (None, None, 256) 0 add_1[0][0]
__________________________________________________________________________________________________
weight_normalization_5 (WeightN (None, None, 256) 197121 leaky_re_lu_5[0][0]
__________________________________________________________________________________________________
leaky_re_lu_6 (LeakyReLU) (None, None, 256) 0 weight_normalization_5[0][0]
__________________________________________________________________________________________________
weight_normalization_6 (WeightN (None, None, 256) 197121 leaky_re_lu_6[0][0]
__________________________________________________________________________________________________
add_2 (Add) (None, None, 256) 0 weight_normalization_6[0][0]
add_1[0][0]
__________________________________________________________________________________________________
leaky_re_lu_7 (LeakyReLU) (None, None, 256) 0 add_2[0][0]
__________________________________________________________________________________________________
weight_normalization_7 (WeightN (None, None, 128) 524673 leaky_re_lu_7[0][0]
__________________________________________________________________________________________________
leaky_re_lu_8 (LeakyReLU) (None, None, 128) 0 weight_normalization_7[0][0]
__________________________________________________________________________________________________
weight_normalization_8 (WeightN (None, None, 128) 49409 leaky_re_lu_8[0][0]
__________________________________________________________________________________________________
leaky_re_lu_9 (LeakyReLU) (None, None, 128) 0 weight_normalization_8[0][0]
__________________________________________________________________________________________________
weight_normalization_9 (WeightN (None, None, 128) 49409 leaky_re_lu_9[0][0]
__________________________________________________________________________________________________
add_3 (Add) (None, None, 128) 0 weight_normalization_9[0][0]
leaky_re_lu_8[0][0]
__________________________________________________________________________________________________
leaky_re_lu_10 (LeakyReLU) (None, None, 128) 0 add_3[0][0]
__________________________________________________________________________________________________
weight_normalization_10 (Weight (None, None, 128) 49409 leaky_re_lu_10[0][0]
__________________________________________________________________________________________________
leaky_re_lu_11 (LeakyReLU) (None, None, 128) 0 weight_normalization_10[0][0]
__________________________________________________________________________________________________
weight_normalization_11 (Weight (None, None, 128) 49409 leaky_re_lu_11[0][0]
__________________________________________________________________________________________________
add_4 (Add) (None, None, 128) 0 add_3[0][0]
weight_normalization_11[0][0]
__________________________________________________________________________________________________
leaky_re_lu_12 (LeakyReLU) (None, None, 128) 0 add_4[0][0]
__________________________________________________________________________________________________
weight_normalization_12 (Weight (None, None, 128) 49409 leaky_re_lu_12[0][0]
__________________________________________________________________________________________________
leaky_re_lu_13 (LeakyReLU) (None, None, 128) 0 weight_normalization_12[0][0]
__________________________________________________________________________________________________
weight_normalization_13 (Weight (None, None, 128) 49409 leaky_re_lu_13[0][0]
__________________________________________________________________________________________________
add_5 (Add) (None, None, 128) 0 weight_normalization_13[0][0]
add_4[0][0]
__________________________________________________________________________________________________
leaky_re_lu_14 (LeakyReLU) (None, None, 128) 0 add_5[0][0]
__________________________________________________________________________________________________
weight_normalization_14 (Weight (None, None, 64) 131265 leaky_re_lu_14[0][0]
__________________________________________________________________________________________________
leaky_re_lu_15 (LeakyReLU) (None, None, 64) 0 weight_normalization_14[0][0]
__________________________________________________________________________________________________
weight_normalization_15 (Weight (None, None, 64) 12417 leaky_re_lu_15[0][0]
__________________________________________________________________________________________________
leaky_re_lu_16 (LeakyReLU) (None, None, 64) 0 weight_normalization_15[0][0]
__________________________________________________________________________________________________
weight_normalization_16 (Weight (None, None, 64) 12417 leaky_re_lu_16[0][0]
__________________________________________________________________________________________________
add_6 (Add) (None, None, 64) 0 weight_normalization_16[0][0]
leaky_re_lu_15[0][0]
__________________________________________________________________________________________________
leaky_re_lu_17 (LeakyReLU) (None, None, 64) 0 add_6[0][0]
__________________________________________________________________________________________________
weight_normalization_17 (Weight (None, None, 64) 12417 leaky_re_lu_17[0][0]
__________________________________________________________________________________________________
leaky_re_lu_18 (LeakyReLU) (None, None, 64) 0 weight_normalization_17[0][0]
__________________________________________________________________________________________________
weight_normalization_18 (Weight (None, None, 64) 12417 leaky_re_lu_18[0][0]
__________________________________________________________________________________________________
add_7 (Add) (None, None, 64) 0 add_6[0][0]
weight_normalization_18[0][0]
__________________________________________________________________________________________________
leaky_re_lu_19 (LeakyReLU) (None, None, 64) 0 add_7[0][0]
__________________________________________________________________________________________________
weight_normalization_19 (Weight (None, None, 64) 12417 leaky_re_lu_19[0][0]
__________________________________________________________________________________________________
leaky_re_lu_20 (LeakyReLU) (None, None, 64) 0 weight_normalization_19[0][0]
__________________________________________________________________________________________________
weight_normalization_20 (Weight (None, None, 64) 12417 leaky_re_lu_20[0][0]
__________________________________________________________________________________________________
add_8 (Add) (None, None, 64) 0 weight_normalization_20[0][0]
add_7[0][0]
__________________________________________________________________________________________________
leaky_re_lu_21 (LeakyReLU) (None, None, 64) 0 add_8[0][0]
__________________________________________________________________________________________________
weight_normalization_21 (Weight (None, None, 32) 32865 leaky_re_lu_21[0][0]
__________________________________________________________________________________________________
leaky_re_lu_22 (LeakyReLU) (None, None, 32) 0 weight_normalization_21[0][0]
__________________________________________________________________________________________________
weight_normalization_22 (Weight (None, None, 32) 3137 leaky_re_lu_22[0][0]
__________________________________________________________________________________________________
leaky_re_lu_23 (LeakyReLU) (None, None, 32) 0 weight_normalization_22[0][0]
__________________________________________________________________________________________________
weight_normalization_23 (Weight (None, None, 32) 3137 leaky_re_lu_23[0][0]
__________________________________________________________________________________________________
add_9 (Add) (None, None, 32) 0 weight_normalization_23[0][0]
leaky_re_lu_22[0][0]
__________________________________________________________________________________________________
leaky_re_lu_24 (LeakyReLU) (None, None, 32) 0 add_9[0][0]
__________________________________________________________________________________________________
weight_normalization_24 (Weight (None, None, 32) 3137 leaky_re_lu_24[0][0]
__________________________________________________________________________________________________
leaky_re_lu_25 (LeakyReLU) (None, None, 32) 0 weight_normalization_24[0][0]
__________________________________________________________________________________________________
weight_normalization_25 (Weight (None, None, 32) 3137 leaky_re_lu_25[0][0]
__________________________________________________________________________________________________
add_10 (Add) (None, None, 32) 0 add_9[0][0]
weight_normalization_25[0][0]
__________________________________________________________________________________________________
leaky_re_lu_26 (LeakyReLU) (None, None, 32) 0 add_10[0][0]
__________________________________________________________________________________________________
weight_normalization_26 (Weight (None, None, 32) 3137 leaky_re_lu_26[0][0]
__________________________________________________________________________________________________
leaky_re_lu_27 (LeakyReLU) (None, None, 32) 0 weight_normalization_26[0][0]
__________________________________________________________________________________________________
weight_normalization_27 (Weight (None, None, 32) 3137 leaky_re_lu_27[0][0]
__________________________________________________________________________________________________
add_11 (Add) (None, None, 32) 0 weight_normalization_27[0][0]
add_10[0][0]
__________________________________________________________________________________________________
leaky_re_lu_28 (LeakyReLU) (None, None, 32) 0 add_11[0][0]
__________________________________________________________________________________________________
weight_normalization_28 (Weight (None, None, 1) 452 leaky_re_lu_28[0][0]
==================================================================================================
Total params: 4,646,912
Trainable params: 4,646,658
Non-trainable params: 254
__________________________________________________________________________________________________
创建判别器
def create_discriminator(input_shape):
inp = keras.Input(input_shape)
out_map1 = discriminator_block(inp)
pool1 = layers.AveragePooling1D()(inp)
out_map2 = discriminator_block(pool1)
pool2 = layers.AveragePooling1D()(pool1)
out_map3 = discriminator_block(pool2)
return keras.Model(inp, [out_map1, out_map2, out_map3])
# We use a dynamic input shape for the discriminator
# This is done because the input shape for the generator is unknown
discriminator = create_discriminator((None, 1))
discriminator.summary()
Model: "model_1"
__________________________________________________________________________________________________
Layer (type) Output Shape Param # Connected to
==================================================================================================
input_2 (InputLayer) [(None, None, 1)] 0
__________________________________________________________________________________________________
average_pooling1d (AveragePooli (None, None, 1) 0 input_2[0][0]
__________________________________________________________________________________________________
average_pooling1d_1 (AveragePoo (None, None, 1) 0 average_pooling1d[0][0]
__________________________________________________________________________________________________
weight_normalization_29 (Weight (None, None, 16) 273 input_2[0][0]
__________________________________________________________________________________________________
weight_normalization_36 (Weight (None, None, 16) 273 average_pooling1d[0][0]
__________________________________________________________________________________________________
weight_normalization_43 (Weight (None, None, 16) 273 average_pooling1d_1[0][0]
__________________________________________________________________________________________________
leaky_re_lu_29 (LeakyReLU) (None, None, 16) 0 weight_normalization_29[0][0]
__________________________________________________________________________________________________
leaky_re_lu_35 (LeakyReLU) (None, None, 16) 0 weight_normalization_36[0][0]
__________________________________________________________________________________________________
leaky_re_lu_41 (LeakyReLU) (None, None, 16) 0 weight_normalization_43[0][0]
__________________________________________________________________________________________________
weight_normalization_30 (Weight (None, None, 64) 10625 leaky_re_lu_29[0][0]
__________________________________________________________________________________________________
weight_normalization_37 (Weight (None, None, 64) 10625 leaky_re_lu_35[0][0]
__________________________________________________________________________________________________
weight_normalization_44 (Weight (None, None, 64) 10625 leaky_re_lu_41[0][0]
__________________________________________________________________________________________________
leaky_re_lu_30 (LeakyReLU) (None, None, 64) 0 weight_normalization_30[0][0]
__________________________________________________________________________________________________
leaky_re_lu_36 (LeakyReLU) (None, None, 64) 0 weight_normalization_37[0][0]
__________________________________________________________________________________________________
leaky_re_lu_42 (LeakyReLU) (None, None, 64) 0 weight_normalization_44[0][0]
__________________________________________________________________________________________________
weight_normalization_31 (Weight (None, None, 256) 42497 leaky_re_lu_30[0][0]
__________________________________________________________________________________________________
weight_normalization_38 (Weight (None, None, 256) 42497 leaky_re_lu_36[0][0]
__________________________________________________________________________________________________
weight_normalization_45 (Weight (None, None, 256) 42497 leaky_re_lu_42[0][0]
__________________________________________________________________________________________________
leaky_re_lu_31 (LeakyReLU) (None, None, 256) 0 weight_normalization_31[0][0]
__________________________________________________________________________________________________
leaky_re_lu_37 (LeakyReLU) (None, None, 256) 0 weight_normalization_38[0][0]
__________________________________________________________________________________________________
leaky_re_lu_43 (LeakyReLU) (None, None, 256) 0 weight_normalization_45[0][0]
__________________________________________________________________________________________________
weight_normalization_32 (Weight (None, None, 1024) 169985 leaky_re_lu_31[0][0]
__________________________________________________________________________________________________
weight_normalization_39 (Weight (None, None, 1024) 169985 leaky_re_lu_37[0][0]
__________________________________________________________________________________________________
weight_normalization_46 (Weight (None, None, 1024) 169985 leaky_re_lu_43[0][0]
__________________________________________________________________________________________________
leaky_re_lu_32 (LeakyReLU) (None, None, 1024) 0 weight_normalization_32[0][0]
__________________________________________________________________________________________________
leaky_re_lu_38 (LeakyReLU) (None, None, 1024) 0 weight_normalization_39[0][0]
__________________________________________________________________________________________________
leaky_re_lu_44 (LeakyReLU) (None, None, 1024) 0 weight_normalization_46[0][0]
__________________________________________________________________________________________________
weight_normalization_33 (Weight (None, None, 1024) 169985 leaky_re_lu_32[0][0]
__________________________________________________________________________________________________
weight_normalization_40 (Weight (None, None, 1024) 169985 leaky_re_lu_38[0][0]
__________________________________________________________________________________________________
weight_normalization_47 (Weight (None, None, 1024) 169985 leaky_re_lu_44[0][0]
__________________________________________________________________________________________________
leaky_re_lu_33 (LeakyReLU) (None, None, 1024) 0 weight_normalization_33[0][0]
__________________________________________________________________________________________________
leaky_re_lu_39 (LeakyReLU) (None, None, 1024) 0 weight_normalization_40[0][0]
__________________________________________________________________________________________________
leaky_re_lu_45 (LeakyReLU) (None, None, 1024) 0 weight_normalization_47[0][0]
__________________________________________________________________________________________________
weight_normalization_34 (Weight (None, None, 1024) 5244929 leaky_re_lu_33[0][0]
__________________________________________________________________________________________________
weight_normalization_41 (Weight (None, None, 1024) 5244929 leaky_re_lu_39[0][0]
__________________________________________________________________________________________________
weight_normalization_48 (Weight (None, None, 1024) 5244929 leaky_re_lu_45[0][0]
__________________________________________________________________________________________________
leaky_re_lu_34 (LeakyReLU) (None, None, 1024) 0 weight_normalization_34[0][0]
__________________________________________________________________________________________________
leaky_re_lu_40 (LeakyReLU) (None, None, 1024) 0 weight_normalization_41[0][0]
__________________________________________________________________________________________________
leaky_re_lu_46 (LeakyReLU) (None, None, 1024) 0 weight_normalization_48[0][0]
__________________________________________________________________________________________________
weight_normalization_35 (Weight (None, None, 1) 3075 leaky_re_lu_34[0][0]
__________________________________________________________________________________________________
weight_normalization_42 (Weight (None, None, 1) 3075 leaky_re_lu_40[0][0]
__________________________________________________________________________________________________
weight_normalization_49 (Weight (None, None, 1) 3075 leaky_re_lu_46[0][0]
==================================================================================================
Total params: 16,924,107
Trainable params: 16,924,086
Non-trainable params: 21
__________________________________________________________________________________________________
定义损失函数
生成器损失
生成器架构使用两种损失的组合
- 均方误差
这是在 1 和具有 N 层的判别器的输出之间计算的标准 MSE 生成器损失。
- 特征匹配损失
此损失涉及从生成器和真实值中提取判别器每一层的输出，并使用平均绝对误差比较每一层输出 k。
判别器损失
判别器使用平均绝对误差，并将真实数据预测与 1 进行比较，并将生成数据预测与 0 进行比较。
# Generator loss
def generator_loss(real_pred, fake_pred):
"""Loss function for the generator.
Args:
real_pred: Tensor, output of the ground truth wave passed through the discriminator.
fake_pred: Tensor, output of the generator prediction passed through the discriminator.
Returns:
Loss for the generator.
"""
gen_loss = []
for i in range(len(fake_pred)):
gen_loss.append(mse(tf.ones_like(fake_pred[i][-1]), fake_pred[i][-1]))
return tf.reduce_mean(gen_loss)
def feature_matching_loss(real_pred, fake_pred):
"""Implements the feature matching loss.
Args:
real_pred: Tensor, output of the ground truth wave passed through the discriminator.
fake_pred: Tensor, output of the generator prediction passed through the discriminator.
Returns:
Feature Matching Loss.
"""
fm_loss = []
for i in range(len(fake_pred)):
for j in range(len(fake_pred[i]) - 1):
fm_loss.append(mae(real_pred[i][j], fake_pred[i][j]))
return tf.reduce_mean(fm_loss)
def discriminator_loss(real_pred, fake_pred):
"""Implements the discriminator loss.
Args:
real_pred: Tensor, output of the ground truth wave passed through the discriminator.
fake_pred: Tensor, output of the generator prediction passed through the discriminator.
Returns:
Discriminator Loss.
"""
real_loss, fake_loss = [], []
for i in range(len(real_pred)):
real_loss.append(mse(tf.ones_like(real_pred[i][-1]), real_pred[i][-1]))
fake_loss.append(mse(tf.zeros_like(fake_pred[i][-1]), fake_pred[i][-1]))
# Calculating the final discriminator loss after scaling
disc_loss = tf.reduce_mean(real_loss) + tf.reduce_mean(fake_loss)
return disc_loss
定义用于训练的 MelGAN 模型。此子类重写 train_step() 方法以实现训练逻辑。
class MelGAN(keras.Model):
def __init__(self, generator, discriminator, **kwargs):
"""MelGAN trainer class
Args:
generator: keras.Model, Generator model
discriminator: keras.Model, Discriminator model
"""
super().__init__(**kwargs)
self.generator = generator
self.discriminator = discriminator
def compile(
self,
gen_optimizer,
disc_optimizer,
generator_loss,
feature_matching_loss,
discriminator_loss,
):
"""MelGAN compile method.
Args:
gen_optimizer: keras.optimizer, optimizer to be used for training
disc_optimizer: keras.optimizer, optimizer to be used for training
generator_loss: callable, loss function for generator
feature_matching_loss: callable, loss function for feature matching
discriminator_loss: callable, loss function for discriminator
"""
super().compile()
# Optimizers
self.gen_optimizer = gen_optimizer
self.disc_optimizer = disc_optimizer
# Losses
self.generator_loss = generator_loss
self.feature_matching_loss = feature_matching_loss
self.discriminator_loss = discriminator_loss
# Trackers
self.gen_loss_tracker = keras.metrics.Mean(name="gen_loss")
self.disc_loss_tracker = keras.metrics.Mean(name="disc_loss")
def train_step(self, batch):
x_batch_train, y_batch_train = batch
with tf.GradientTape() as gen_tape, tf.GradientTape() as disc_tape:
# Generating the audio wave
gen_audio_wave = generator(x_batch_train, training=True)
# Generating the features using the discriminator
real_pred = discriminator(y_batch_train)
fake_pred = discriminator(gen_audio_wave)
# Calculating the generator losses
gen_loss = generator_loss(real_pred, fake_pred)
fm_loss = feature_matching_loss(real_pred, fake_pred)
# Calculating final generator loss
gen_fm_loss = gen_loss + 10 * fm_loss
# Calculating the discriminator losses
disc_loss = discriminator_loss(real_pred, fake_pred)
# Calculating and applying the gradients for generator and discriminator
grads_gen = gen_tape.gradient(gen_fm_loss, generator.trainable_weights)
grads_disc = disc_tape.gradient(disc_loss, discriminator.trainable_weights)
gen_optimizer.apply_gradients(zip(grads_gen, generator.trainable_weights))
disc_optimizer.apply_gradients(zip(grads_disc, discriminator.trainable_weights))
self.gen_loss_tracker.update_state(gen_fm_loss)
self.disc_loss_tracker.update_state(disc_loss)
return {
"gen_loss": self.gen_loss_tracker.result(),
"disc_loss": self.disc_loss_tracker.result(),
}
训练
论文建议使用动态形状进行训练大约需要 400,000 步（约 500 个 epoch）。对于此示例，我们只运行一个 epoch（819 步）。更长的训练时间（超过 300 个 epoch）几乎肯定可以提供更好的结果。
gen_optimizer = keras.optimizers.Adam(
LEARNING_RATE_GEN, beta_1=0.5, beta_2=0.9, clipnorm=1
)
disc_optimizer = keras.optimizers.Adam(
LEARNING_RATE_DISC, beta_1=0.5, beta_2=0.9, clipnorm=1
)
# Start training
generator = create_generator((None, 1))
discriminator = create_discriminator((None, 1))
mel_gan = MelGAN(generator, discriminator)
mel_gan.compile(
gen_optimizer,
disc_optimizer,
generator_loss,
feature_matching_loss,
discriminator_loss,
)
mel_gan.fit(
train_dataset.shuffle(200).batch(BATCH_SIZE).prefetch(tf.data.AUTOTUNE), epochs=1
)
819/819 [==============================] - 641s 696ms/step - gen_loss: 0.9761 - disc_loss: 0.9350
<keras.callbacks.History at 0x7f8f702fe050>
测试模型
现在，训练后的模型可用于实时文本到语音翻译任务。为了测试 MelGAN 推理的速度，让我们获取一个样本音频梅尔声谱图并将其转换。请注意，实际模型管道将不包含 MelSpec 层，因此在推理期间将禁用此层。推理输入将是类似于 MelSpec 层配置处理的梅尔声谱图。
为了进行测试，我们将创建一个随机均匀分布的张量来模拟推理管道的行为。
# Sampling a random tensor to mimic a batch of 128 spectrograms of shape [50, 80]
audio_sample = tf.random.uniform([128, 50, 80])
计时单个样本的推理速度。运行此操作，您会发现每个声谱图的平均推理时间在 K80 GPU 上大约为 8 毫秒到 10 毫秒，这非常快。
pred = generator.predict(audio_sample, batch_size=32, verbose=1)
4/4 [==============================] - 5s 280ms/step
结论
MelGAN 是一种用于频谱反演的高效架构，其平均意见得分 (MOS) 为 3.61，大大优于 MOS 仅为 1.57 的 Griffin-Lim 算法。相比之下，MelGAN 在 LJSpeech 和 VCTK 数据集上的文本到语音和语音增强任务中与最先进的 WaveGlow 和 WaveNet 架构相媲美 [1]。
本教程重点介绍
- 使用随着滤波器大小增长的扩张卷积的优势
- 实现自定义层以动态地将音频波形转换为梅尔声谱图
- 使用特征匹配损失函数训练 GAN 生成器的有效性。
进一步阅读
- MelGAN 论文（Kundan Kumar 等人）以了解架构和训练过程背后的原因
- 要深入了解特征匹配损失，您可以参考 改进的 GAN 训练技术（Tim Salimans 等人）。
HuggingFace 上提供的示例
| 训练模型 | 演示 |
|---|---|
 |
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