186 lines
5.9 KiB
Python
186 lines
5.9 KiB
Python
# Copyright 2020 Smeet Shah
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# MIT License (https://opensource.org/licenses/MIT)
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import torch
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import torch.nn as nn
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import torch.nn.functional as F
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class Visual_encoder(nn.Module):
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def __init__(self, args):
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super(Visual_encoder, self).__init__()
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self.args = args
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# visual frontend
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self.v_frontend = VisualFrontend(args)
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self.v_ds = nn.Conv1d(512, 256, 1, bias=False)
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# visual adaptor
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stacks = []
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for x in range(5):
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stacks +=[VisualConv1D(args, V=256, H=512)]
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self.visual_conv = nn.Sequential(*stacks)
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def forward(self, visual):
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visual = self.v_frontend(visual.unsqueeze(1))
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visual = self.v_ds(visual)
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visual = self.visual_conv(visual)
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return visual
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class ResNetLayer(nn.Module):
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"""
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A ResNet layer used to build the ResNet network.
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Architecture:
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--> conv-bn-relu -> conv -> + -> bn-relu -> conv-bn-relu -> conv -> + -> bn-relu -->
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-----> downsample ------> ------------------------------------->
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"""
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def __init__(self, inplanes, outplanes, stride):
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super(ResNetLayer, self).__init__()
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self.conv1a = nn.Conv2d(inplanes, outplanes, kernel_size=3, stride=stride, padding=1, bias=False)
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self.bn1a = nn.BatchNorm2d(outplanes, momentum=0.01, eps=0.001)
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self.conv2a = nn.Conv2d(outplanes, outplanes, kernel_size=3, stride=1, padding=1, bias=False)
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self.stride = stride
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self.downsample = nn.Conv2d(inplanes, outplanes, kernel_size=(1,1), stride=stride, bias=False)
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self.outbna = nn.BatchNorm2d(outplanes, momentum=0.01, eps=0.001)
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self.conv1b = nn.Conv2d(outplanes, outplanes, kernel_size=3, stride=1, padding=1, bias=False)
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self.bn1b = nn.BatchNorm2d(outplanes, momentum=0.01, eps=0.001)
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self.conv2b = nn.Conv2d(outplanes, outplanes, kernel_size=3, stride=1, padding=1, bias=False)
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self.outbnb = nn.BatchNorm2d(outplanes, momentum=0.01, eps=0.001)
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return
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def forward(self, inputBatch):
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batch = F.relu(self.bn1a(self.conv1a(inputBatch)))
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batch = self.conv2a(batch)
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if self.stride == 1:
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residualBatch = inputBatch
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else:
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residualBatch = self.downsample(inputBatch)
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batch = batch + residualBatch
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intermediateBatch = batch
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batch = F.relu(self.outbna(batch))
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batch = F.relu(self.bn1b(self.conv1b(batch)))
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batch = self.conv2b(batch)
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residualBatch = intermediateBatch
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batch = batch + residualBatch
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outputBatch = F.relu(self.outbnb(batch))
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return outputBatch
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class ResNet(nn.Module):
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"""
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An 18-layer ResNet architecture.
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"""
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def __init__(self):
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super(ResNet, self).__init__()
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self.layer1 = ResNetLayer(64, 64, stride=1)
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self.layer2 = ResNetLayer(64, 128, stride=2)
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self.layer3 = ResNetLayer(128, 256, stride=2)
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self.layer4 = ResNetLayer(256, 512, stride=2)
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self.avgpool = nn.AvgPool2d(kernel_size=(4,4), stride=(1,1))
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return
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def forward(self, inputBatch):
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batch = self.layer1(inputBatch)
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batch = self.layer2(batch)
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batch = self.layer3(batch)
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batch = self.layer4(batch)
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outputBatch = self.avgpool(batch)
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return outputBatch
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class VisualFrontend(nn.Module):
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"""
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A visual feature extraction module. Generates a 512-dim feature vector per video frame.
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Architecture: A 3D convolution block followed by an 18-layer ResNet.
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"""
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def __init__(self, args):
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super(VisualFrontend, self).__init__()
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self.args =args
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if self.args.causal:
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padding = (4,3,3)
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else:
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padding = (2,3,3)
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self.frontend3D = nn.Sequential(
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nn.Conv3d(1, 64, kernel_size=(5,7,7), stride=(1,2,2), padding=padding, bias=False),
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nn.BatchNorm3d(64, momentum=0.01, eps=0.001),
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nn.ReLU(),
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nn.MaxPool3d(kernel_size=(1,3,3), stride=(1,2,2), padding=(0,1,1))
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)
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self.resnet = ResNet()
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return
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def forward(self, batch):
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batchsize = batch.shape[0]
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batch = self.frontend3D[0](batch)
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if self.args.causal:
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batch = batch[:,:,:-4,:,:]
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batch = self.frontend3D[1](batch)
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batch = self.frontend3D[2](batch)
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batch = self.frontend3D[3](batch)
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batch = batch.transpose(1, 2)
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batch = batch.reshape(batch.shape[0]*batch.shape[1], batch.shape[2], batch.shape[3], batch.shape[4])
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outputBatch = self.resnet(batch)
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outputBatch = outputBatch.reshape(batchsize, -1, 512)
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outputBatch = outputBatch.transpose(1 ,2)
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return outputBatch
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class VisualConv1D(nn.Module):
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def __init__(self, args, V=256, H=512, kernel_size=3, dilation=1):
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super(VisualConv1D, self).__init__()
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self.args =args
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self.relu_0 = nn.ReLU()
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self.norm_0 = nn.BatchNorm1d(V)
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self.conv1x1 = nn.Conv1d(V, H, 1, bias=False)
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self.relu = nn.ReLU()
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self.norm_1 = nn.BatchNorm1d(H)
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self.dconv_pad = (dilation * (kernel_size - 1)) // 2 if not self.args.causal else (
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dilation * (kernel_size - 1))
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self.dsconv = nn.Conv1d(H, H, kernel_size, stride=1, padding=self.dconv_pad, dilation=1, groups=H)
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self.prelu = nn.PReLU()
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self.norm_2 = nn.BatchNorm1d(H)
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self.pw_conv = nn.Conv1d(H, V, 1, bias=False)
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def forward(self, x):
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out = self.relu_0(x)
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out = self.norm_0(out)
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out = self.conv1x1(out)
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out = self.relu(out)
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out = self.norm_1(out)
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out = self.dsconv(out)
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if self.args.causal:
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out = out[:, :, :-self.dconv_pad]
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out = self.prelu(out)
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out = self.norm_2(out)
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out = self.pw_conv(out)
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return out + x
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