Task-Specific Alignment and Multiple Level Transformer for Few-Shot Action Recognition

In the research field of few-shot learning, the main difference between image-based and video-based is the additional temporal dimension for videos. In recent years, many approaches for few-shot action recognition have followed the metric-based methods, especially, since some works use the Transformer to get the cross-attention feature of the videos or the enhanced prototype, and the results are competitive. However, they do not mine enough information from the Transformer because they only focus on the feature of a single level. In our paper, we have addressed this problem. We propose an end-to-end method named "Task-Specific Alignment and Multiple Level Transformer Network (TSA-MLT)". In our model, the Multiple Level Transformer focuses on the multiple-level feature of the support video and query video. Especially before Multiple Level Transformer, we use task-specific TSA to filter unimportant or misleading frames as a pre-processing. Furthermore, we adopt a fusion loss using two kinds of distance, the first is L2 sequence distance, which focuses on temporal order alignment. The second one is Optimal transport distance, which focuses on measuring the gap between the appearance and semantics of the videos. Using a simple fusion network, we fuse the two distances element-wise, then use the cross-entropy loss as our fusion loss. Extensive experiments show our method achieves state-of-the-art results on the HMDB51 and UCF101 datasets and a competitive result on the benchmark of Kinetics and something-2-something V2 datasets. Our code will be available at the URL: https://github.com/cofly2014/tsa-mlt.git