def _construct_network()

in timesformer/models/video_model_builder.py [0:0]


    def _construct_network(self, cfg):
        """
        Builds a single pathway ResNet model.

        Args:
            cfg (CfgNode): model building configs, details are in the
                comments of the config file.
        """
        assert cfg.MODEL.ARCH in _POOL1.keys()
        pool_size = _POOL1[cfg.MODEL.ARCH]
        assert len({len(pool_size), self.num_pathways}) == 1
        assert cfg.RESNET.DEPTH in _MODEL_STAGE_DEPTH.keys()

        (d2, d3, d4, d5) = _MODEL_STAGE_DEPTH[cfg.RESNET.DEPTH]

        num_groups = cfg.RESNET.NUM_GROUPS
        width_per_group = cfg.RESNET.WIDTH_PER_GROUP
        dim_inner = num_groups * width_per_group

        temp_kernel = _TEMPORAL_KERNEL_BASIS[cfg.MODEL.ARCH]

        self.s1 = stem_helper.VideoModelStem(
            dim_in=cfg.DATA.INPUT_CHANNEL_NUM,
            dim_out=[width_per_group],
            kernel=[temp_kernel[0][0] + [7, 7]],
            stride=[[1, 2, 2]],
            padding=[[temp_kernel[0][0][0] // 2, 3, 3]],
            norm_module=self.norm_module,
        )

        self.s2 = resnet_helper.ResStage(
            dim_in=[width_per_group],
            dim_out=[width_per_group * 4],
            dim_inner=[dim_inner],
            temp_kernel_sizes=temp_kernel[1],
            stride=cfg.RESNET.SPATIAL_STRIDES[0],
            num_blocks=[d2],
            num_groups=[num_groups],
            num_block_temp_kernel=cfg.RESNET.NUM_BLOCK_TEMP_KERNEL[0],
            nonlocal_inds=cfg.NONLOCAL.LOCATION[0],
            nonlocal_group=cfg.NONLOCAL.GROUP[0],
            nonlocal_pool=cfg.NONLOCAL.POOL[0],
            instantiation=cfg.NONLOCAL.INSTANTIATION,
            trans_func_name=cfg.RESNET.TRANS_FUNC,
            stride_1x1=cfg.RESNET.STRIDE_1X1,
            inplace_relu=cfg.RESNET.INPLACE_RELU,
            dilation=cfg.RESNET.SPATIAL_DILATIONS[0],
            norm_module=self.norm_module,
        )

        for pathway in range(self.num_pathways):
            pool = nn.MaxPool3d(
                kernel_size=pool_size[pathway],
                stride=pool_size[pathway],
                padding=[0, 0, 0],
            )
            self.add_module("pathway{}_pool".format(pathway), pool)

        self.s3 = resnet_helper.ResStage(
            dim_in=[width_per_group * 4],
            dim_out=[width_per_group * 8],
            dim_inner=[dim_inner * 2],
            temp_kernel_sizes=temp_kernel[2],
            stride=cfg.RESNET.SPATIAL_STRIDES[1],
            num_blocks=[d3],
            num_groups=[num_groups],
            num_block_temp_kernel=cfg.RESNET.NUM_BLOCK_TEMP_KERNEL[1],
            nonlocal_inds=cfg.NONLOCAL.LOCATION[1],
            nonlocal_group=cfg.NONLOCAL.GROUP[1],
            nonlocal_pool=cfg.NONLOCAL.POOL[1],
            instantiation=cfg.NONLOCAL.INSTANTIATION,
            trans_func_name=cfg.RESNET.TRANS_FUNC,
            stride_1x1=cfg.RESNET.STRIDE_1X1,
            inplace_relu=cfg.RESNET.INPLACE_RELU,
            dilation=cfg.RESNET.SPATIAL_DILATIONS[1],
            norm_module=self.norm_module,
        )

        self.s4 = resnet_helper.ResStage(
            dim_in=[width_per_group * 8],
            dim_out=[width_per_group * 16],
            dim_inner=[dim_inner * 4],
            temp_kernel_sizes=temp_kernel[3],
            stride=cfg.RESNET.SPATIAL_STRIDES[2],
            num_blocks=[d4],
            num_groups=[num_groups],
            num_block_temp_kernel=cfg.RESNET.NUM_BLOCK_TEMP_KERNEL[2],
            nonlocal_inds=cfg.NONLOCAL.LOCATION[2],
            nonlocal_group=cfg.NONLOCAL.GROUP[2],
            nonlocal_pool=cfg.NONLOCAL.POOL[2],
            instantiation=cfg.NONLOCAL.INSTANTIATION,
            trans_func_name=cfg.RESNET.TRANS_FUNC,
            stride_1x1=cfg.RESNET.STRIDE_1X1,
            inplace_relu=cfg.RESNET.INPLACE_RELU,
            dilation=cfg.RESNET.SPATIAL_DILATIONS[2],
            norm_module=self.norm_module,
        )

        self.s5 = resnet_helper.ResStage(
            dim_in=[width_per_group * 16],
            dim_out=[width_per_group * 32],
            dim_inner=[dim_inner * 8],
            temp_kernel_sizes=temp_kernel[4],
            stride=cfg.RESNET.SPATIAL_STRIDES[3],
            num_blocks=[d5],
            num_groups=[num_groups],
            num_block_temp_kernel=cfg.RESNET.NUM_BLOCK_TEMP_KERNEL[3],
            nonlocal_inds=cfg.NONLOCAL.LOCATION[3],
            nonlocal_group=cfg.NONLOCAL.GROUP[3],
            nonlocal_pool=cfg.NONLOCAL.POOL[3],
            instantiation=cfg.NONLOCAL.INSTANTIATION,
            trans_func_name=cfg.RESNET.TRANS_FUNC,
            stride_1x1=cfg.RESNET.STRIDE_1X1,
            inplace_relu=cfg.RESNET.INPLACE_RELU,
            dilation=cfg.RESNET.SPATIAL_DILATIONS[3],
            norm_module=self.norm_module,
        )

        if self.enable_detection:
            self.head = head_helper.ResNetRoIHead(
                dim_in=[width_per_group * 32],
                num_classes=cfg.MODEL.NUM_CLASSES,
                pool_size=[[cfg.DATA.NUM_FRAMES // pool_size[0][0], 1, 1]],
                resolution=[[cfg.DETECTION.ROI_XFORM_RESOLUTION] * 2],
                scale_factor=[cfg.DETECTION.SPATIAL_SCALE_FACTOR],
                dropout_rate=cfg.MODEL.DROPOUT_RATE,
                act_func=cfg.MODEL.HEAD_ACT,
                aligned=cfg.DETECTION.ALIGNED,
            )
        else:
            head = head_helper.ResNetBasicHead(
                dim_in=[width_per_group * 32],
                num_classes=cfg.MODEL.NUM_CLASSES,
                pool_size=[None, None]
                if cfg.MULTIGRID.SHORT_CYCLE
                else [
                    [
                        cfg.DATA.NUM_FRAMES // pool_size[0][0],
                        cfg.DATA.TRAIN_CROP_SIZE // 32 // pool_size[0][1],
                        cfg.DATA.TRAIN_CROP_SIZE // 32 // pool_size[0][2],
                    ]
                ],  # None for AdaptiveAvgPool3d((1, 1, 1))
                dropout_rate=cfg.MODEL.DROPOUT_RATE,
                act_func=cfg.MODEL.HEAD_ACT,
            )
            self.head_name = "head{}".format(cfg.TASK)
            self.add_module(self.head_name, head)