Glance Forcing: Making Bidirectional Diffusion Autoregressive at a Glance
Organizations: Wuhan University · University of Electronic Science and Technology of China · Sun Yat-sen University · University of Washington ·
Abstract
Autoregressive generation underlies real-time, causal video synthesis and is the backbone of video world models. Today's dominant approach distills a bidirectional diffusion model into a causal few-step student, but existing pipelines make this conversion prohibitively expensive, requiring offline Probability Flow ODE} (PF-ODE) trajectories that cost tens of thousands of GPU-hours and terabytes of storage. We show it can be made dramatically more efficient. Pushing this efficiency to its extreme, we reduce trajectory supervision to a single sample, the strictest setting possible, and find that it causes severe quality collapse. We trace this to the teacher's trajectory geometry: the high-noise regime, governing semantic layout and motion, and the low-noise regime, governing fine texture exhibit fundamentally different curvature and optimization behavior, so a single monolithic student cannot jointly fit both, causing severe representation interference. Motivated by this, we propose Glance Forcing, a lightweight distillation framework that decouples the denoising trajectory into two complementary slow and fast experts, each guided by a tailored, stage-specific objective, while keeping the pretrained teacher entirely frozen. This decoupling further reveals a general mechanism underlying few-step distillation: PF-ODE distillation mainly straightens the few-step trajectory geometry, while the subsequent distribution-matching stage independently governs distributional quality. Using only one PF-ODE trajectory, Glance Forcing already surpasses the fully-trained state-of-the-art baseline, raising the VBench Total score from 84.04 to 84.22 while cutting trajectory-collection cost from thousands of GPU-hours to about one A100-GPU-hour, with markedly larger gains in dynamic degree, VisionReward, and instruction-following, and consistent preference from human raters over strong baselines.
Figures & tables
| Model | Data | Thru. | Latency | Total | Quality | Semantic | Dyn. | Vision. | Instruct. |
| Bidirectional Video Diffusion Models | |||||||||
| Wan2.1-1.3B | - | 0.78 | 103 | 83.37 | 84.30 | 79.65 | 61 | 5.275 | 42 |
| LTX-1.9B | - | 8.98 | 13.5 | 79.83 | 81.88 | 71.62 | 46 | -6.218 | -38 |
| Autoregressive Video Diffusion Models | |||||||||
| SkyReels-V2 | - | 0.49 | 112 | 81.97 | 83.96 | 74.01 | 37 | 3.584 | 32 |
| MAGI-1 | - | 0.19 | 282 | 78.88 | 81.67 | 67.72 | 42 | 0.773 | 8 |
Appendix figures & tables4 assets
Supplementary material from the paper’s appendix.