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"""VGG2L module definition for custom encoder."""
from typing import Tuple, Union
import torch
class VGG2L(torch.nn.Module):
"""VGG2L module for custom encoder.
Args:
idim: Input dimension.
odim: Output dimension.
pos_enc: Positional encoding class.
"""
def __init__(self, idim: int, odim: int, pos_enc: torch.nn.Module = None):
"""Construct a VGG2L object."""
super().__init__()
self.vgg2l = torch.nn.Sequential(
torch.nn.Conv2d(1, 64, 3, stride=1, padding=1),
torch.nn.ReLU(),
torch.nn.Conv2d(64, 64, 3, stride=1, padding=1),
torch.nn.ReLU(),
torch.nn.MaxPool2d((3, 2)),
torch.nn.Conv2d(64, 128, 3, stride=1, padding=1),
torch.nn.ReLU(),
torch.nn.Conv2d(128, 128, 3, stride=1, padding=1),
torch.nn.ReLU(),
torch.nn.MaxPool2d((2, 2)),
)
if pos_enc is not None:
self.output = torch.nn.Sequential(
torch.nn.Linear(128 * ((idim // 2) // 2), odim), pos_enc
)
else:
self.output = torch.nn.Linear(128 * ((idim // 2) // 2), odim)
def forward(self, feats: torch.Tensor, feats_mask: torch.Tensor) -> Union[
Tuple[torch.Tensor, torch.Tensor],
Tuple[Tuple[torch.Tensor, torch.Tensor], torch.Tensor],
]:
"""Forward VGG2L bottleneck.
Args:
feats: Feature sequences. (B, F, D_feats)
feats_mask: Mask of feature sequences. (B, 1, F)
Returns:
vgg_output: VGG output sequences.
(B, sub(F), D_out) or ((B, sub(F), D_out), (B, sub(F), D_att))
vgg_mask: Mask of VGG output sequences. (B, 1, sub(F))
"""
feats = feats.unsqueeze(1)
vgg_output = self.vgg2l(feats)
b, c, t, f = vgg_output.size()
vgg_output = self.output(
vgg_output.transpose(1, 2).contiguous().view(b, t, c * f)
)
if feats_mask is not None:
vgg_mask = self.create_new_mask(feats_mask)
else:
vgg_mask = feats_mask
return vgg_output, vgg_mask
def create_new_mask(self, feats_mask: torch.Tensor) -> torch.Tensor:
"""Create a subsampled mask of feature sequences.
Args:
feats_mask: Mask of feature sequences. (B, 1, F)
Returns:
vgg_mask: Mask of VGG2L output sequences. (B, 1, sub(F))
"""
vgg1_t_len = feats_mask.size(2) - (feats_mask.size(2) % 3)
vgg_mask = feats_mask[:, :, :vgg1_t_len][:, :, ::3]
vgg2_t_len = vgg_mask.size(2) - (vgg_mask.size(2) % 2)
vgg_mask = vgg_mask[:, :, :vgg2_t_len][:, :, ::2]
return vgg_mask