CAST: Cross-Attentive Spatio-Temporal feature fusion for Deepfake detection

Abstract: Deepfakes have emerged as a significant threat to digital media authenticity, increasing the need for advanced detection techniques that can identify subtle and time-dependent manipulations. CNNs are effective at capturing spatial artifacts, and Transformers excel at modeling temporal inconsistencies. However, many existing CNN-Transformer models process spatial and temporal features independently. In particular, attention-based methods often use separate attention mechanisms for spatial and temporal features and combine them using naive approaches like averaging, addition, or concatenation, which limits the depth of spatio-temporal interaction. To address this challenge, we propose a unified CAST model that leverages cross-attention to effectively fuse spatial and temporal features in a more integrated manner. Our approach allows temporal features to dynamically attend to relevant spatial regions, enhancing the model's ability to detect fine-grained, time-evolving artifacts such as flickering eyes or warped lips. This design enables more precise localization and deeper contextual understanding, leading to improved performance across diverse and challenging scenarios. We evaluate the performance of our model using the FaceForensics++, Celeb-DF, and DeepfakeDetection datasets in both intra- and cross-dataset settings to affirm the superiority of our approach. Our model achieves strong performance with an AUC of 99.49 percent and an accuracy of 97.57 percent in intra-dataset evaluations. In cross-dataset testing, it demonstrates impressive generalization by achieving a 93.31 percent AUC on the unseen DeepfakeDetection dataset. These results highlight the effectiveness of cross-attention-based feature fusion in enhancing the robustness of deepfake video detection.