Next Forcing: Causal World Modeling with Multi-Chunk Prediction

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2026年06月09日
自回归视频生成已成为世界动作模型(WAMs)的一种强大范式。然而,现有方法普遍存在训练收敛速度慢、最终收敛精度有限的问题——尤其在高帧率场景下更为突出,其根本原因在于训练监督信号仅局限于当前视频片段,缺乏对后续动态演化的显式建模;此外,由于需通过迭代式视频去噪完成生成,其推理过程也十分缓慢。本文提出“下一帧强制”(Next Forcing)方法,这是一种面向因果世界建模的多片段预测(Multi-Chunk Prediction, MCP)框架,可显著提升训练速度、增强建模精度,并大幅加速推理过程。受大语言模型中多词元预测(multi-token prediction)思想的启发,“下一帧强制”引入了一种新型MCP训练目标:在主干模型基础上,额外添加若干轻量级辅助MCP模块,使其能够同步对多个未来时间步长(即“下一第1段”“下一第2段”“下一第3段”视频片段)进行联合去噪。这些MCP模块按预测深度构成一条因果链:各模块利用来自主干模型多个网络层的中间特征进行融合,从而逐级建模未来动态演化——较近未来的预测结果可为更远未来的预测提供信息支撑,同时向主干模型回传密集、多尺度的时间维度监督信号。在训练阶段,MCP模块显著加快了模型收敛速度并提升了最终收敛精度,尤其在高帧率条件下效果突出:在50 fps帧率下,仅经过5000步训练,“下一帧强制”相较LingBot-VA模型相对性能提升达93.1%,收敛速度提升2.3倍;并在RoboTwin基准测试中刷新了最高纪录(Clean与Random子集得分分别达94.1%和93.5%)。在推理阶段,MCP模块可被保留并用于与当前视频片段并行预测下一个视频片段,从而实现2倍的推理加速。此外,“下一帧强制”在PhyWorld基准测试(用于评估视频生成结果对物理规律的遵循程度)上亦展现出显著性能提升,并在通用视频预训练任务中实现了超过50%的FVD(Fréchet Video Distance)指标下降。
Autoregressive video generation has emerged as a powerful paradigm for World Action Models (WAMs). However, existing approaches suffer from slow training convergence and limited converged accuracy, particularly at high frame rates, as the training supervision is confined to the current chunk without explicit signals about future dynamics; they also suffer from slow inference due to iterative video denoising. In this paper, we present Next Forcing, a multi-chunk prediction (MCP) framework for causal world modeling that enables faster training, higher accuracy, and accelerated inference. Inspired by multi-token prediction in large language models, Next Forcing introduces an MCP training objective that augments the main model with lightweight auxiliary MCP modules to simultaneously denoise video chunks at multiple future temporal horizons (next$^1$, next$^2$, next$^3$ chunks). These MCP modules form a causal chain across prediction depths, where intermediate features fused from multiple layers of the main model are leveraged to predict future dynamics, allowing near-future predictions to inform farther-future ones and providing dense multi-scale temporal supervision back to the main model. During training, the MCP modules significantly accelerate convergence and improve converged accuracy, especially at high frame rates: at 50 fps, Next Forcing achieves a 93.1% relative improvement over LingBot-VA at 5k training steps and 2.3x faster convergence, and establishes new state-of-the-art results on the RoboTwin benchmark (94.1/93.5% on Clean/Random). At inference, the MCP modules can be retained to predict the next video chunk in parallel with the current one, achieving 2x inference acceleration. Next Forcing also demonstrates significant improvements on PhyWorld, a benchmark evaluating adherence to physical laws in video generation, and over 50% FVD reduction on general video pretraining.
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