Token Reduction via Local and Global Contexts Optimization for Efficient Video Large Language Models

TL;DR

This paper introduces a novel token reduction method for Video Large Language Models using local and global context optimization via optimal transport, significantly improving efficiency while maintaining performance.

Contribution

It proposes a training-free token anchoring and aggregation approach with local-global optimal transport for efficient video understanding in LLMs.

Findings

Achieves substantial computational efficiency on various video benchmarks.

Maintains high temporal and visual fidelity despite token reduction.

Outperforms existing pruning methods in spatiotemporal reduction.

Abstract

Video Large Language Models (VLLMs) demonstrate strong video understanding but suffer from inefficiency due to redundant visual tokens. Existing pruning primary targets intra-frame spatial redundancy or prunes inside the LLM with shallow-layer overhead, yielding suboptimal spatiotemporal reduction and underutilizing long-context compressibility. All of them often discard subtle yet informative context from merged or pruned tokens. In this paper, we propose a new perspective that elaborates token \textbf{A}nchors within intra-frame and inter-frame to comprehensively aggregate the informative contexts via local-global \textbf{O}ptimal \textbf{T}ransport (\textbf{AOT}). Specifically, we first establish local- and global-aware token anchors within each frame under the attention guidance, which then optimal transport aggregates the informative contexts from pruned tokens, constructing intra-frame token anchors. Then, building on the temporal frame clips, the first frame within each clip will be considered as the keyframe anchors to ensemble similar information from consecutive frames through optimal transport, while keeping distinct tokens to represent temporal dynamics, leading to efficient token reduction in a training-free manner. Extensive evaluations show that our proposed AOT obtains competitive performances across various short- and long-video benchmarks on leading video LLMs, obtaining substantial computational efficiency while preserving temporal and visual fidelity. Project webpage: https://tyroneli.github.io/AOT.