Source code for torchvision.models.video.resnet
from functools import partial
from typing import Tuple, Optional, Callable, List, Sequence, Type, Any, Union
import torch.nn as nn
from torch import Tensor
from ...transforms._presets import VideoClassification
from ...utils import _log_api_usage_once
from .._api import WeightsEnum, Weights
from .._meta import _KINETICS400_CATEGORIES
from .._utils import handle_legacy_interface, _ovewrite_named_param
__all__ = [
"VideoResNet",
"R3D_18_Weights",
"MC3_18_Weights",
"R2Plus1D_18_Weights",
"r3d_18",
"mc3_18",
"r2plus1d_18",
]
class Conv3DSimple(nn.Conv3d):
def __init__(
self, in_planes: int, out_planes: int, midplanes: Optional[int] = None, stride: int = 1, padding: int = 1
) -> None:
super().__init__(
in_channels=in_planes,
out_channels=out_planes,
kernel_size=(3, 3, 3),
stride=stride,
padding=padding,
bias=False,
)
@staticmethod
def get_downsample_stride(stride: int) -> Tuple[int, int, int]:
return stride, stride, stride
class Conv2Plus1D(nn.Sequential):
def __init__(self, in_planes: int, out_planes: int, midplanes: int, stride: int = 1, padding: int = 1) -> None:
super().__init__(
nn.Conv3d(
in_planes,
midplanes,
kernel_size=(1, 3, 3),
stride=(1, stride, stride),
padding=(0, padding, padding),
bias=False,
),
nn.BatchNorm3d(midplanes),
nn.ReLU(inplace=True),
nn.Conv3d(
midplanes, out_planes, kernel_size=(3, 1, 1), stride=(stride, 1, 1), padding=(padding, 0, 0), bias=False
),
)
@staticmethod
def get_downsample_stride(stride: int) -> Tuple[int, int, int]:
return stride, stride, stride
class Conv3DNoTemporal(nn.Conv3d):
def __init__(
self, in_planes: int, out_planes: int, midplanes: Optional[int] = None, stride: int = 1, padding: int = 1
) -> None:
super().__init__(
in_channels=in_planes,
out_channels=out_planes,
kernel_size=(1, 3, 3),
stride=(1, stride, stride),
padding=(0, padding, padding),
bias=False,
)
@staticmethod
def get_downsample_stride(stride: int) -> Tuple[int, int, int]:
return 1, stride, stride
class BasicBlock(nn.Module):
expansion = 1
def __init__(
self,
inplanes: int,
planes: int,
conv_builder: Callable[..., nn.Module],
stride: int = 1,
downsample: Optional[nn.Module] = None,
) -> None:
midplanes = (inplanes * planes * 3 * 3 * 3) // (inplanes * 3 * 3 + 3 * planes)
super().__init__()
self.conv1 = nn.Sequential(
conv_builder(inplanes, planes, midplanes, stride), nn.BatchNorm3d(planes), nn.ReLU(inplace=True)
)
self.conv2 = nn.Sequential(conv_builder(planes, planes, midplanes), nn.BatchNorm3d(planes))
self.relu = nn.ReLU(inplace=True)
self.downsample = downsample
self.stride = stride
def forward(self, x: Tensor) -> Tensor:
residual = x
out = self.conv1(x)
out = self.conv2(out)
if self.downsample is not None:
residual = self.downsample(x)
out += residual
out = self.relu(out)
return out
class Bottleneck(nn.Module):
expansion = 4
def __init__(
self,
inplanes: int,
planes: int,
conv_builder: Callable[..., nn.Module],
stride: int = 1,
downsample: Optional[nn.Module] = None,
) -> None:
super().__init__()
midplanes = (inplanes * planes * 3 * 3 * 3) // (inplanes * 3 * 3 + 3 * planes)
# 1x1x1
self.conv1 = nn.Sequential(
nn.Conv3d(inplanes, planes, kernel_size=1, bias=False), nn.BatchNorm3d(planes), nn.ReLU(inplace=True)
)
# Second kernel
self.conv2 = nn.Sequential(
conv_builder(planes, planes, midplanes, stride), nn.BatchNorm3d(planes), nn.ReLU(inplace=True)
)
# 1x1x1
self.conv3 = nn.Sequential(
nn.Conv3d(planes, planes * self.expansion, kernel_size=1, bias=False),
nn.BatchNorm3d(planes * self.expansion),
)
self.relu = nn.ReLU(inplace=True)
self.downsample = downsample
self.stride = stride
def forward(self, x: Tensor) -> Tensor:
residual = x
out = self.conv1(x)
out = self.conv2(out)
out = self.conv3(out)
if self.downsample is not None:
residual = self.downsample(x)
out += residual
out = self.relu(out)
return out
class BasicStem(nn.Sequential):
"""The default conv-batchnorm-relu stem"""
def __init__(self) -> None:
super().__init__(
nn.Conv3d(3, 64, kernel_size=(3, 7, 7), stride=(1, 2, 2), padding=(1, 3, 3), bias=False),
nn.BatchNorm3d(64),
nn.ReLU(inplace=True),
)
class R2Plus1dStem(nn.Sequential):
"""R(2+1)D stem is different than the default one as it uses separated 3D convolution"""
def __init__(self) -> None:
super().__init__(
nn.Conv3d(3, 45, kernel_size=(1, 7, 7), stride=(1, 2, 2), padding=(0, 3, 3), bias=False),
nn.BatchNorm3d(45),
nn.ReLU(inplace=True),
nn.Conv3d(45, 64, kernel_size=(3, 1, 1), stride=(1, 1, 1), padding=(1, 0, 0), bias=False),
nn.BatchNorm3d(64),
nn.ReLU(inplace=True),
)
class VideoResNet(nn.Module):
def __init__(
self,
block: Type[Union[BasicBlock, Bottleneck]],
conv_makers: Sequence[Type[Union[Conv3DSimple, Conv3DNoTemporal, Conv2Plus1D]]],
layers: List[int],
stem: Callable[..., nn.Module],
num_classes: int = 400,
zero_init_residual: bool = False,
) -> None:
"""Generic resnet video generator.
Args:
block (Type[Union[BasicBlock, Bottleneck]]): resnet building block
conv_makers (List[Type[Union[Conv3DSimple, Conv3DNoTemporal, Conv2Plus1D]]]): generator
function for each layer
layers (List[int]): number of blocks per layer
stem (Callable[..., nn.Module]): module specifying the ResNet stem.
num_classes (int, optional): Dimension of the final FC layer. Defaults to 400.
zero_init_residual (bool, optional): Zero init bottleneck residual BN. Defaults to False.
"""
super().__init__()
_log_api_usage_once(self)
self.inplanes = 64
self.stem = stem()
self.layer1 = self._make_layer(block, conv_makers[0], 64, layers[0], stride=1)
self.layer2 = self._make_layer(block, conv_makers[1], 128, layers[1], stride=2)
self.layer3 = self._make_layer(block, conv_makers[2], 256, layers[2], stride=2)
self.layer4 = self._make_layer(block, conv_makers[3], 512, layers[3], stride=2)
self.avgpool = nn.AdaptiveAvgPool3d((1, 1, 1))
self.fc = nn.Linear(512 * block.expansion, num_classes)
# init weights
for m in self.modules():
if isinstance(m, nn.Conv3d):
nn.init.kaiming_normal_(m.weight, mode="fan_out", nonlinearity="relu")
if m.bias is not None:
nn.init.constant_(m.bias, 0)
elif isinstance(m, nn.BatchNorm3d):
nn.init.constant_(m.weight, 1)
nn.init.constant_(m.bias, 0)
elif isinstance(m, nn.Linear):
nn.init.normal_(m.weight, 0, 0.01)
nn.init.constant_(m.bias, 0)
if zero_init_residual:
for m in self.modules():
if isinstance(m, Bottleneck):
nn.init.constant_(m.bn3.weight, 0) # type: ignore[union-attr, arg-type]
def forward(self, x: Tensor) -> Tensor:
x = self.stem(x)
x = self.layer1(x)
x = self.layer2(x)
x = self.layer3(x)
x = self.layer4(x)
x = self.avgpool(x)
# Flatten the layer to fc
x = x.flatten(1)
x = self.fc(x)
return x
def _make_layer(
self,
block: Type[Union[BasicBlock, Bottleneck]],
conv_builder: Type[Union[Conv3DSimple, Conv3DNoTemporal, Conv2Plus1D]],
planes: int,
blocks: int,
stride: int = 1,
) -> nn.Sequential:
downsample = None
if stride != 1 or self.inplanes != planes * block.expansion:
ds_stride = conv_builder.get_downsample_stride(stride)
downsample = nn.Sequential(
nn.Conv3d(self.inplanes, planes * block.expansion, kernel_size=1, stride=ds_stride, bias=False),
nn.BatchNorm3d(planes * block.expansion),
)
layers = []
layers.append(block(self.inplanes, planes, conv_builder, stride, downsample))
self.inplanes = planes * block.expansion
for i in range(1, blocks):
layers.append(block(self.inplanes, planes, conv_builder))
return nn.Sequential(*layers)
def _video_resnet(
block: Type[Union[BasicBlock, Bottleneck]],
conv_makers: Sequence[Type[Union[Conv3DSimple, Conv3DNoTemporal, Conv2Plus1D]]],
layers: List[int],
stem: Callable[..., nn.Module],
weights: Optional[WeightsEnum],
progress: bool,
**kwargs: Any,
) -> VideoResNet:
if weights is not None:
_ovewrite_named_param(kwargs, "num_classes", len(weights.meta["categories"]))
model = VideoResNet(block, conv_makers, layers, stem, **kwargs)
if weights is not None:
model.load_state_dict(weights.get_state_dict(progress=progress))
return model
_COMMON_META = {
"min_size": (1, 1),
"categories": _KINETICS400_CATEGORIES,
"recipe": "https://github.com/pytorch/vision/tree/main/references/video_classification",
"_docs": """These weights reproduce closely the accuracy of the paper for 16-frame clip inputs.""",
}
[docs]class R3D_18_Weights(WeightsEnum):
KINETICS400_V1 = Weights(
url="https://download.pytorch.org/models/r3d_18-b3b3357e.pth",
transforms=partial(VideoClassification, crop_size=(112, 112), resize_size=(128, 171)),
meta={
**_COMMON_META,
"num_params": 33371472,
"_metrics": {
"Kinetics-400": {
"acc@1": 52.75,
"acc@5": 75.45,
}
},
},
)
DEFAULT = KINETICS400_V1
[docs]class MC3_18_Weights(WeightsEnum):
KINETICS400_V1 = Weights(
url="https://download.pytorch.org/models/mc3_18-a90a0ba3.pth",
transforms=partial(VideoClassification, crop_size=(112, 112), resize_size=(128, 171)),
meta={
**_COMMON_META,
"num_params": 11695440,
"_metrics": {
"Kinetics-400": {
"acc@1": 53.90,
"acc@5": 76.29,
}
},
},
)
DEFAULT = KINETICS400_V1
[docs]class R2Plus1D_18_Weights(WeightsEnum):
KINETICS400_V1 = Weights(
url="https://download.pytorch.org/models/r2plus1d_18-91a641e6.pth",
transforms=partial(VideoClassification, crop_size=(112, 112), resize_size=(128, 171)),
meta={
**_COMMON_META,
"num_params": 31505325,
"_metrics": {
"Kinetics-400": {
"acc@1": 57.50,
"acc@5": 78.81,
}
},
},
)
DEFAULT = KINETICS400_V1
[docs]@handle_legacy_interface(weights=("pretrained", R3D_18_Weights.KINETICS400_V1))
def r3d_18(*, weights: Optional[R3D_18_Weights] = None, progress: bool = True, **kwargs: Any) -> VideoResNet:
"""Construct 18 layer Resnet3D model.
.. betastatus:: video module
Reference: `A Closer Look at Spatiotemporal Convolutions for Action Recognition <https://arxiv.org/abs/1711.11248>`__.
Args:
weights (:class:`~torchvision.models.video.R3D_18_Weights`, optional): The
pretrained weights to use. See
:class:`~torchvision.models.video.R3D_18_Weights`
below for more details, and possible values. By default, no
pre-trained weights are used.
progress (bool): If True, displays a progress bar of the download to stderr. Default is True.
**kwargs: parameters passed to the ``torchvision.models.video.resnet.VideoResNet`` base class.
Please refer to the `source code
<https://github.com/pytorch/vision/blob/main/torchvision/models/video/resnet.py>`_
for more details about this class.
.. autoclass:: torchvision.models.video.R3D_18_Weights
:members:
"""
weights = R3D_18_Weights.verify(weights)
return _video_resnet(
BasicBlock,
[Conv3DSimple] * 4,
[2, 2, 2, 2],
BasicStem,
weights,
progress,
**kwargs,
)
[docs]@handle_legacy_interface(weights=("pretrained", MC3_18_Weights.KINETICS400_V1))
def mc3_18(*, weights: Optional[MC3_18_Weights] = None, progress: bool = True, **kwargs: Any) -> VideoResNet:
"""Construct 18 layer Mixed Convolution network as in
.. betastatus:: video module
Reference: `A Closer Look at Spatiotemporal Convolutions for Action Recognition <https://arxiv.org/abs/1711.11248>`__.
Args:
weights (:class:`~torchvision.models.video.MC3_18_Weights`, optional): The
pretrained weights to use. See
:class:`~torchvision.models.video.MC3_18_Weights`
below for more details, and possible values. By default, no
pre-trained weights are used.
progress (bool): If True, displays a progress bar of the download to stderr. Default is True.
**kwargs: parameters passed to the ``torchvision.models.video.resnet.VideoResNet`` base class.
Please refer to the `source code
<https://github.com/pytorch/vision/blob/main/torchvision/models/video/resnet.py>`_
for more details about this class.
.. autoclass:: torchvision.models.video.MC3_18_Weights
:members:
"""
weights = MC3_18_Weights.verify(weights)
return _video_resnet(
BasicBlock,
[Conv3DSimple] + [Conv3DNoTemporal] * 3, # type: ignore[list-item]
[2, 2, 2, 2],
BasicStem,
weights,
progress,
**kwargs,
)
[docs]@handle_legacy_interface(weights=("pretrained", R2Plus1D_18_Weights.KINETICS400_V1))
def r2plus1d_18(*, weights: Optional[R2Plus1D_18_Weights] = None, progress: bool = True, **kwargs: Any) -> VideoResNet:
"""Construct 18 layer deep R(2+1)D network as in
.. betastatus:: video module
Reference: `A Closer Look at Spatiotemporal Convolutions for Action Recognition <https://arxiv.org/abs/1711.11248>`__.
Args:
weights (:class:`~torchvision.models.video.R2Plus1D_18_Weights`, optional): The
pretrained weights to use. See
:class:`~torchvision.models.video.R2Plus1D_18_Weights`
below for more details, and possible values. By default, no
pre-trained weights are used.
progress (bool): If True, displays a progress bar of the download to stderr. Default is True.
**kwargs: parameters passed to the ``torchvision.models.video.resnet.VideoResNet`` base class.
Please refer to the `source code
<https://github.com/pytorch/vision/blob/main/torchvision/models/video/resnet.py>`_
for more details about this class.
.. autoclass:: torchvision.models.video.R2Plus1D_18_Weights
:members:
"""
weights = R2Plus1D_18_Weights.verify(weights)
return _video_resnet(
BasicBlock,
[Conv2Plus1D] * 4,
[2, 2, 2, 2],
R2Plus1dStem,
weights,
progress,
**kwargs,
)
# The dictionary below is internal implementation detail and will be removed in v0.15
from .._utils import _ModelURLs
model_urls = _ModelURLs(
{
"r3d_18": R3D_18_Weights.KINETICS400_V1.url,
"mc3_18": MC3_18_Weights.KINETICS400_V1.url,
"r2plus1d_18": R2Plus1D_18_Weights.KINETICS400_V1.url,
}
)
