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# This module is from [WeNet](https://github.com/wenet-e2e/wenet).
# ## Citations
# ```bibtex
# @inproceedings{yao2021wenet,
# title={WeNet: Production oriented Streaming and Non-streaming End-to-End Speech Recognition Toolkit},
# author={Yao, Zhuoyuan and Wu, Di and Wang, Xiong and Zhang, Binbin and Yu, Fan and Yang, Chao and Peng, Zhendong and Chen, Xiaoyu and Xie, Lei and Lei, Xin},
# booktitle={Proc. Interspeech},
# year={2021},
# address={Brno, Czech Republic },
# organization={IEEE}
# }
# @article{zhang2022wenet,
# title={WeNet 2.0: More Productive End-to-End Speech Recognition Toolkit},
# author={Zhang, Binbin and Wu, Di and Peng, Zhendong and Song, Xingchen and Yao, Zhuoyuan and Lv, Hang and Xie, Lei and Yang, Chao and Pan, Fuping and Niu, Jianwei},
# journal={arXiv preprint arXiv:2203.15455},
# year={2022}
# }
#
"""ConvolutionModule definition."""
from typing import Tuple
import torch
from torch import nn
class ConvolutionModule(nn.Module):
"""ConvolutionModule in Conformer model."""
def __init__(
self,
channels: int,
kernel_size: int = 15,
activation: nn.Module = nn.ReLU(),
norm: str = "batch_norm",
causal: bool = False,
bias: bool = True,
stride: int = 1,
):
"""Construct an ConvolutionModule object.
Args:
channels (int): The number of channels of conv layers.
kernel_size (int): Kernel size of conv layers.
causal (int): Whether use causal convolution or not
stride (int): Stride Convolution, for efficient Conformer
"""
super().__init__()
self.pointwise_conv1 = nn.Conv1d(
channels,
2 * channels,
kernel_size=1,
stride=1,
padding=0,
bias=bias,
)
# self.lorder is used to distinguish if it's a causal convolution,
# if self.lorder > 0: it's a causal convolution, the input will be
# padded with self.lorder frames on the left in forward.
# else: it's a symmetrical convolution
if causal:
padding = 0
self.lorder = kernel_size - 1
else:
# kernel_size should be an odd number for none causal convolution
assert (kernel_size - 1) % 2 == 0
padding = (kernel_size - 1) // 2
self.lorder = 0
self.depthwise_conv = nn.Conv1d(
channels,
channels,
kernel_size,
stride=stride, # for depthwise_conv in StrideConv
padding=padding,
groups=channels,
bias=bias,
)
assert norm in ["batch_norm", "layer_norm"]
if norm == "batch_norm":
self.use_layer_norm = False
self.norm = nn.BatchNorm1d(channels)
else:
self.use_layer_norm = True
self.norm = nn.LayerNorm(channels)
self.pointwise_conv2 = nn.Conv1d(
channels,
channels,
kernel_size=1,
stride=1,
padding=0,
bias=bias,
)
self.activation = activation
self.stride = stride
def forward(
self,
x: torch.Tensor,
mask_pad: torch.Tensor = torch.ones((0, 0, 0), dtype=torch.bool),
cache: torch.Tensor = torch.zeros((0, 0, 0)),
) -> Tuple[torch.Tensor, torch.Tensor]:
"""Compute convolution module.
Args:
x (torch.Tensor): Input tensor (#batch, time, channels).
mask_pad (torch.Tensor): used for batch padding (#batch, 1, time),
(0, 0, 0) means fake mask.
cache (torch.Tensor): left context cache, it is only
used in causal convolution (#batch, channels, cache_t),
(0, 0, 0) meas fake cache.
Returns:
torch.Tensor: Output tensor (#batch, time, channels).
"""
# exchange the temporal dimension and the feature dimension
x = x.transpose(1, 2) # (#batch, channels, time)
# mask batch padding
if mask_pad.size(2) > 0: # time > 0
x.masked_fill_(~mask_pad, 0.0)
if self.lorder > 0:
if cache.size(2) == 0: # cache_t == 0
x = nn.functional.pad(x, (self.lorder, 0), "constant", 0.0)
else:
# When export ONNX，the first cache is not None but all-zero,
# cause shape error in residual block,
# eg. cache14 + x9 = 23, 23-7+1=17 != 9
cache = cache[:, :, -self.lorder :]
assert cache.size(0) == x.size(0) # equal batch
assert cache.size(1) == x.size(1) # equal channel
x = torch.cat((cache, x), dim=2)
assert x.size(2) > self.lorder
new_cache = x[:, :, -self.lorder :]
else:
# It's better we just return None if no cache is requried,
# However, for JIT export, here we just fake one tensor instead of
# None.
new_cache = torch.zeros((0, 0, 0), dtype=x.dtype, device=x.device)
# GLU mechanism
x = self.pointwise_conv1(x) # (batch, 2*channel, dim)
x = nn.functional.glu(x, dim=1) # (batch, channel, dim)
# 1D Depthwise Conv
x = self.depthwise_conv(x)
if self.use_layer_norm:
x = x.transpose(1, 2)
x = self.activation(self.norm(x))
if self.use_layer_norm:
x = x.transpose(1, 2)
x = self.pointwise_conv2(x)
# mask batch padding
if mask_pad.size(2) > 0: # time > 0
if mask_pad.size(2) != x.size(2):
mask_pad = mask_pad[:, :, :: self.stride]
x.masked_fill_(~mask_pad, 0.0)
return x.transpose(1, 2), new_cache
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