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import torch
from functools import reduce
import torch.nn as nn
import torch.nn.functional as F
from functools import partial
class FeedForward(nn.Module):
def __init__(self, frame_hidden, mlp_ratio, n_vecs, t2t_params, p):
"""
Args:
frame_hidden: hidden size of frame features
mlp_ratio: mlp ratio in the middle layer of the transformers
n_vecs: number of vectors in the transformer
t2t_params: dictionary -> {'kernel_size': kernel_size, 'stride': stride, 'padding': padding, 'output_size': output_shape}
p: dropout rate, 0 by default
"""
super(FeedForward, self).__init__()
self.conv = nn.Sequential(
nn.Linear(frame_hidden, frame_hidden * mlp_ratio),
nn.ReLU(inplace=True),
nn.Dropout(p),
nn.Linear(frame_hidden * mlp_ratio, frame_hidden),
nn.Dropout(p)
)
def forward(self, x, n_vecs=0, output_h=0, output_w=0):
x = self.conv(x)
return x
class FusionFeedForward(nn.Module):
def __init__(self, frame_hidden, mlp_ratio, n_vecs, t2t_params, p):
super(FusionFeedForward, self).__init__()
self.kernel_shape = reduce((lambda x, y: x * y), t2t_params['kernel_size'])
self.t2t_params = t2t_params
hidden_size = self.kernel_shape * mlp_ratio
self.conv1 = nn.Linear(frame_hidden, hidden_size)
self.conv2 = nn.Sequential(
nn.ReLU(inplace=True),
nn.Dropout(p),
nn.Linear(hidden_size, frame_hidden),
nn.Dropout(p)
)
assert t2t_params is not None and n_vecs is not None
tp = t2t_params.copy()
self.fold = nn.Fold(**tp)
del tp['output_size']
self.unfold = nn.Unfold(**tp)
self.n_vecs = n_vecs
def forward(self, x, n_vecs=0, output_h=0, output_w=0):
x = self.conv1(x)
b, n, c = x.size()
if n_vecs != 0:
normalizer = x.new_ones(b, n, self.kernel_shape).view(-1, n_vecs, self.kernel_shape).permute(0, 2, 1)
x = self.unfold(F.fold(x.view(-1, n_vecs, c).permute(0, 2, 1), output_size=(output_h, output_w),
kernel_size=self.t2t_params['kernel_size'], stride=self.t2t_params['stride'],
padding=self.t2t_params['padding']) / F.fold(normalizer,
output_size=(output_h, output_w),
kernel_size=self.t2t_params[
'kernel_size'],
stride=self.t2t_params['stride'],
padding=self.t2t_params[
'padding'])).permute(0,
2,
1).contiguous().view(
b, n, c)
else:
normalizer = x.new_ones(b, n, self.kernel_shape).view(-1, self.n_vecs, self.kernel_shape).permute(0, 2, 1)
x = self.unfold(self.fold(x.view(-1, self.n_vecs, c).permute(0, 2, 1)) / self.fold(normalizer)).permute(0,
2,
1).contiguous().view(
b, n, c)
x = self.conv2(x)
return x
class ResidualBlock_noBN(nn.Module):
"""Residual block w/o BN
---Conv-ReLU-Conv-+-
|________________|
"""
def __init__(self, nf=64):
super(ResidualBlock_noBN, self).__init__()
self.conv1 = nn.Conv2d(nf, nf, kernel_size=3, stride=1, padding=1, bias=True)
self.conv2 = nn.Conv2d(nf, nf, kernel_size=3, stride=1, padding=1, bias=True)
self.lrelu = nn.LeakyReLU(negative_slope=0.2, inplace=True)
def forward(self, x):
"""
Args:
x: with shape of [b, c, t, h, w]
Returns: processed features with shape [b, c, t, h, w]
"""
identity = x
out = self.lrelu(self.conv1(x))
out = self.conv2(out)
out = identity + out
# Remove ReLU at the end of the residual block
# http://torch.ch/blog/2016/02/04/resnets.html
return out
def make_layer(block, n_layers):
layers = []
for _ in range(n_layers):
layers.append(block())
return nn.Sequential(*layers)