Train Short, Inference Long: Training-free Horizon Extension for Autoregressive Video Generation

Fuente: arXiv
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Main Authors: Li, Jia, Fu, Xiaomeng, Peng, Xurui, Chen, Weifeng, Zheng, Youwei, Zhao, Tianyu, Wang, Jiexi, Chen, Fangmin, Wang, Xing, So, Hayden Kwok-Hay
Format: Preprint
Published: 2026
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author Li, Jia
Fu, Xiaomeng
Peng, Xurui
Chen, Weifeng
Zheng, Youwei
Zhao, Tianyu
Wang, Jiexi
Chen, Fangmin
Wang, Xing
So, Hayden Kwok-Hay
author_facet Li, Jia
Fu, Xiaomeng
Peng, Xurui
Chen, Weifeng
Zheng, Youwei
Zhao, Tianyu
Wang, Jiexi
Chen, Fangmin
Wang, Xing
So, Hayden Kwok-Hay
contents Autoregressive video diffusion models have emerged as a scalable paradigm for long video generation. However, they often suffer from severe extrapolation failure, where rapid error accumulation leads to significant temporal degradation when extending beyond training horizons. We identify that this failure primarily stems from the spectral bias of 3D positional embeddings and the lack of dynamic priors in noise sampling. To address these issues, we propose FLEX (Frequency-aware Length EXtension), a training-free inference-time framework that bridges the gap between short-term training and long-term inference. FLEX introduces Frequency-aware RoPE Modulation to adaptively interpolate under-trained low-frequency components while extrapolating high-frequency ones to preserve multi-scale temporal discriminability. This is integrated with Antiphase Noise Sampling (ANS) to inject high-frequency dynamic priors and Inference-only Attention Sink to anchor global structure. Extensive evaluations on VBench demonstrate that FLEX significantly outperforms state-of-the-art models at 6x extrapolation (30s duration) and matches the performance of long-video fine-tuned baselines at 12x scale (60s duration). As a plug-and-play augmentation, FLEX seamlessly integrates into existing inference pipelines for horizon extension. It effectively pushes the generation limits of models such as LongLive, supporting consistent and dynamic video synthesis at a 4-minute scale. Project page is available at https://ga-lee.github.io/FLEX_demo.
format Preprint
id arxiv_https___arxiv_org_abs_2602_14027
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle Train Short, Inference Long: Training-free Horizon Extension for Autoregressive Video Generation
Li, Jia
Fu, Xiaomeng
Peng, Xurui
Chen, Weifeng
Zheng, Youwei
Zhao, Tianyu
Wang, Jiexi
Chen, Fangmin
Wang, Xing
So, Hayden Kwok-Hay
Computer Vision and Pattern Recognition
Autoregressive video diffusion models have emerged as a scalable paradigm for long video generation. However, they often suffer from severe extrapolation failure, where rapid error accumulation leads to significant temporal degradation when extending beyond training horizons. We identify that this failure primarily stems from the spectral bias of 3D positional embeddings and the lack of dynamic priors in noise sampling. To address these issues, we propose FLEX (Frequency-aware Length EXtension), a training-free inference-time framework that bridges the gap between short-term training and long-term inference. FLEX introduces Frequency-aware RoPE Modulation to adaptively interpolate under-trained low-frequency components while extrapolating high-frequency ones to preserve multi-scale temporal discriminability. This is integrated with Antiphase Noise Sampling (ANS) to inject high-frequency dynamic priors and Inference-only Attention Sink to anchor global structure. Extensive evaluations on VBench demonstrate that FLEX significantly outperforms state-of-the-art models at 6x extrapolation (30s duration) and matches the performance of long-video fine-tuned baselines at 12x scale (60s duration). As a plug-and-play augmentation, FLEX seamlessly integrates into existing inference pipelines for horizon extension. It effectively pushes the generation limits of models such as LongLive, supporting consistent and dynamic video synthesis at a 4-minute scale. Project page is available at https://ga-lee.github.io/FLEX_demo.
title Train Short, Inference Long: Training-free Horizon Extension for Autoregressive Video Generation
topic Computer Vision and Pattern Recognition
url https://arxiv.org/abs/2602.14027