Encoding and Controlling Global Semantics for Long-form Video Question Answering
Thong Thanh Nguyen, Zhiyuan Hu, Xiaobao Wu, Cong-Duy T Nguyen, See-Kiong Ng, Anh Tuan Luu
TL;DR
This work tackles the difficulty of long-form videoQA by introducing a Gated State Space Layer (SSL) within a multi-modal Transformer (GSMT) to inject global video semantics into visual representations. A Cross-modal Compositional Congruence (C^3) objective aligns global visual semantics with the question, enhancing reasoning over extended video sequences. The authors also curate two large-scale long-form benchmarks, Ego-QA and MAD-QA, to rigorously evaluate long-range QA capabilities. Comprehensive experiments, ablations, and qualitative analyses demonstrate substantial gains over strong baselines, highlighting the significance of global semantic integration for real-world, hour-scale videos.
Abstract
Seeking answers effectively for long videos is essential to build video question answering (videoQA) systems. Previous methods adaptively select frames and regions from long videos to save computations. However, this fails to reason over the whole sequence of video, leading to sub-optimal performance. To address this problem, we introduce a state space layer (SSL) into multi-modal Transformer to efficiently integrate global semantics of the video, which mitigates the video information loss caused by frame and region selection modules. Our SSL includes a gating unit to enable controllability over the flow of global semantics into visual representations. To further enhance the controllability, we introduce a cross-modal compositional congruence (C^3) objective to encourage global semantics aligned with the question. To rigorously evaluate long-form videoQA capacity, we construct two new benchmarks Ego-QA and MAD-QA featuring videos of considerably long length, i.e. 17.5 minutes and 1.9 hours, respectively. Extensive experiments demonstrate the superiority of our framework on these new as well as existing datasets. The code, model, and data have been made available at https://nguyentthong.github.io/Long_form_VideoQA.
