def extract_feature_3d(self, x: torch.Tensor) -> torch.Tensor:
        """ get the appearance feature of the image by F
        x: Bx3xHxW, normalized to 0~1
        """
        with torch.no_grad():
            feature_3d = self.appearance_feature_extractor(x)

        return feature_3d.float()
 get the appearance feature of the image by F
        x: Bx3xHxW, normalized to 0~1
        
modules/live_portrait/live_portrait_wrapper.py