File size: 3,236 Bytes
35c1cfd
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
# MIT License
#
# Copyright 2023 ByteDance Inc.
#
# Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the “Software”),
# to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense,
# and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions:
#
# The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software.
#
# THE SOFTWARE IS PROVIDED “AS IS”, WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
# FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
# LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
# IN THE SOFTWARE.

from torch import nn
from einops import rearrange


class Res2dModule(nn.Module):
    def __init__(self, idim, odim, stride=(2, 2)):
        super(Res2dModule, self).__init__()
        self.conv1 = nn.Conv2d(idim, odim, 3, padding=1, stride=stride)
        self.bn1 = nn.BatchNorm2d(odim)
        self.conv2 = nn.Conv2d(odim, odim, 3, padding=1)
        self.bn2 = nn.BatchNorm2d(odim)
        self.relu = nn.ReLU()

        # residual
        self.diff = False
        if (idim != odim) or (stride[0] > 1):
            self.conv3 = nn.Conv2d(idim, odim, 3, padding=1, stride=stride)
            self.bn3 = nn.BatchNorm2d(odim)
            self.diff = True

    def forward(self, x):
        out = self.bn2(self.conv2(self.relu(self.bn1(self.conv1(x)))))
        if self.diff:
            x = self.bn3(self.conv3(x))
        out = x + out
        out = self.relu(out)
        return out


class Conv2dSubsampling(nn.Module):
    """Convolutional 2D subsampling (to 1/4 length).



    Args:

        idim (int): Input dimension.

        hdim (int): Hidden dimension.

        odim (int): Output dimension.

        strides (list): Sizes of strides.

        n_bands (int): Number of frequency bands.

    """

    def __init__(self, idim, hdim, odim, strides=[2, 2], n_bands=64):
        """Construct an Conv2dSubsampling object."""
        super(Conv2dSubsampling, self).__init__()

        self.conv = nn.Sequential(
            Res2dModule(idim, hdim, (2, strides[0])),
            Res2dModule(hdim, hdim, (2, strides[1])),
        )
        self.linear = nn.Linear(hdim * n_bands // 2 // 2, odim)

    def forward(self, x):
        """Subsample x.



        Args:

            x (torch.Tensor): Input tensor (#batch, idim, time).



        Returns:

            torch.Tensor: Subsampled tensor (#batch, time', odim),

                where time' = time // 4.

        """

        if x.dim() == 3:
            x = x.unsqueeze(1)  # (b, c, f, t)
        x = self.conv(x)
        x = rearrange(x, "b c f t -> b t (c f)")
        x = self.linear(x)
        return x