Token-Efficient Long Video Understanding for Multimodal LLMs
Authors: name: Jindong Jiang, name: Xiuyu Li, name: Zhijian Liu, name: Muyang Li, name: Guo Chen, name: Zhiqi Li, name: De-An Huang, name: Guilin Liu, name: Zhiding Yu, name: Kurt Keutzer, name: Sungjin Ahn, name: Jan Kautz, name: Hongxu Yin, name: Yao Lu, name: Song Han, name: Wonmin Byeon

Recent advances in video-based multimodal large language models (Video-LLMs)
have significantly improved video understanding by processing videos as
sequences of image frames. However, many existing methods treat frames
independently in the vision backbone, lacking explicit temporal modeling, which
limits their ability to capture dynamic patterns and efficiently handle long
videos. To address these limitations, we introduce STORM
(Spatiotemporal TOken Reduction for
Multimodal LLMs), a novel architecture incorporating a dedicated
temporal encoder between the image encoder and the LLM. Our temporal encoder
leverages the Mamba State Space Model to integrate temporal information into
image tokens, generating enriched representations that preserve inter-frame
dynamics across the entire video sequence. This enriched encoding not only
enhances video reasoning capabilities but also enables effective token
reduction strategies, including test-time sampling and training-based temporal
and spatial pooling, substantially reducing computational demands on the LLM
without sacrificing key temporal information. By integrating these techniques,
our approach simultaneously reduces training and inference latency while
improving performance, enabling efficient and robust video understanding over
extended temporal contexts. Extensive evaluations show that STORM achieves
state-of-the-art results across various long video understanding benchmarks
(more than 5\% improvement on MLVU and LongVideoBench) while reducing the
computation costs by up to 8times and the decoding latency by
2.4-2.9times for the fixed numbers of input frames. Project page is
available at https://research.nvidia.com/labs/lpr/storm