VideoSSM: Autoregressive Long Video Generation with Hybrid State-Space Memory
Authors: name: Yifei Yu, name: Xiaoshan Wu, name: Xinting Hu, name: Tao Hu, name: Yangtian Sun, name: Xiaoyang Lyu, name: Bo Wang, name: Lin Ma, name: Yuewen Ma, name: Zhongrui Wang, name: Xiaojuan Qi
Organization: The University of Hong Kong

Autoregressive (AR) diffusion enables streaming, interactive long-video generation by producing frames causally, yet maintaining coherence over minute-scale horizons remains challenging due to accumulated errors, motion drift, and content repetition. We approach this problem from a memory perspective, treating video synthesis as a recurrent dynamical process that requires coordinated short- and long-term context. We propose VideoSSM, a Long Video Model that unifies AR diffusion with a hybrid state-space memory. The state-space model (SSM) serves as an evolving global memory of scene dynamics across the entire sequence, while a context window provides local memory for motion cues and fine details. This hybrid design preserves global consistency without frozen, repetitive patterns, supports prompt-adaptive interaction, and scales in linear time with sequence length. Experiments on short- and long-range benchmarks demonstrate state-of-the-art temporal consistency and motion stability among autoregressive video generator especially at minute-scale horizons, enabling content diversity and interactive prompt-based control, thereby establishing a scalable, memory-aware framework for long video generation.