PredToken: Predicting Unknown Tokens and Beyond with Coarse-to-Fine Iterative Decoding
Authors: Xuesong Nie, Haoyuan Jin, Yunfeng Yan, Xi Chen, Zhihang Zhu, Donglian Qi

Predictive learning models which aim to predict future frames based on past observations are crucial to constructing world models. These models need to maintain low-level consistency and capture high-level dynamics in unannotated spatiotemporal data. Transitioning from frame-wise to token-wise prediction presents a viable strategy for addressing these needs. How to improve token representation and optimize token decoding presents significant challenges. This paper introduces PredToken a novel predictive framework that addresses these issues by decoupling space-time tokens into distinct components for iterative cascaded decoding. Concretely we first design a "decomposition quantization and reconstruction" schema based on VQGAN to improve the token representation. This scheme disentangles low- and high-frequency representations and employs a dimension-aware quantization model allowing more low-level details to be preserved. Building on this we present a "coarse-to-fine iterative decoding" method. It leverages dynamic soft decoding to refine coarse tokens and static soft decoding for fine tokens enabling more high-level dynamics to be captured. These designs make PredToken produce high-quality predictions. Extensive experiments demonstrate the superiority of our method on various real-world spatiotemporal predictive benchmarks. Furthermore PredToken can also be extended to other visual generative tasks to yield realistic outcomes.