SpecVLM: Enhancing Speculative Decoding of Video LLMs via Verifier-Guided Token Pruning

Fuente: arXiv
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Autores principales: Ji, Yicheng, Zhang, Jun, Xia, Heming, Chen, Jinpeng, Shou, Lidan, Chen, Gang, Li, Huan
Formato: Preprint
Publicado: 2025
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author Ji, Yicheng
Zhang, Jun
Xia, Heming
Chen, Jinpeng
Shou, Lidan
Chen, Gang
Li, Huan
author_facet Ji, Yicheng
Zhang, Jun
Xia, Heming
Chen, Jinpeng
Shou, Lidan
Chen, Gang
Li, Huan
contents Video large language models (Vid-LLMs) have shown strong capabilities in understanding video content. However, their reliance on dense video token representations introduces substantial memory and computational overhead in both prefilling and decoding. To mitigate the information loss of recent video token reduction methods and accelerate the decoding stage of Vid-LLMs losslessly, we introduce SpecVLM, a training-free speculative decoding (SD) framework tailored for Vid-LLMs that incorporates staged video token pruning. Building on our novel finding that the draft model's speculation exhibits low sensitivity to video token pruning, SpecVLM prunes up to 90% of video tokens to enable efficient speculation without sacrificing accuracy. To achieve this, we performs a two-stage pruning process: Stage I selects highly informative tokens guided by attention signals from the verifier (target model), while Stage II prunes remaining redundant ones in a spatially uniform manner. Extensive experiments on four video understanding benchmarks demonstrate the effectiveness and robustness of SpecVLM, which achieves up to 2.68$\times$ decoding speedup for LLaVA-OneVision-72B and 2.11$\times$ speedup for Qwen2.5-VL-32B. Code is available at https://github.com/zju-jiyicheng/SpecVLM.
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id arxiv_https___arxiv_org_abs_2508_16201
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle SpecVLM: Enhancing Speculative Decoding of Video LLMs via Verifier-Guided Token Pruning
Ji, Yicheng
Zhang, Jun
Xia, Heming
Chen, Jinpeng
Shou, Lidan
Chen, Gang
Li, Huan
Computer Vision and Pattern Recognition
Artificial Intelligence
Computation and Language
Video large language models (Vid-LLMs) have shown strong capabilities in understanding video content. However, their reliance on dense video token representations introduces substantial memory and computational overhead in both prefilling and decoding. To mitigate the information loss of recent video token reduction methods and accelerate the decoding stage of Vid-LLMs losslessly, we introduce SpecVLM, a training-free speculative decoding (SD) framework tailored for Vid-LLMs that incorporates staged video token pruning. Building on our novel finding that the draft model's speculation exhibits low sensitivity to video token pruning, SpecVLM prunes up to 90% of video tokens to enable efficient speculation without sacrificing accuracy. To achieve this, we performs a two-stage pruning process: Stage I selects highly informative tokens guided by attention signals from the verifier (target model), while Stage II prunes remaining redundant ones in a spatially uniform manner. Extensive experiments on four video understanding benchmarks demonstrate the effectiveness and robustness of SpecVLM, which achieves up to 2.68$\times$ decoding speedup for LLaVA-OneVision-72B and 2.11$\times$ speedup for Qwen2.5-VL-32B. Code is available at https://github.com/zju-jiyicheng/SpecVLM.
title SpecVLM: Enhancing Speculative Decoding of Video LLMs via Verifier-Guided Token Pruning
topic Computer Vision and Pattern Recognition
Artificial Intelligence
Computation and Language
url https://arxiv.org/abs/2508.16201