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VideoChat3: Fully Open Video MLLM for Efficient and Generalist Video Understanding

Enables efficient, generalist video understanding by combining an Inflated 3D Vision Transformer and adaptive frame-resolution streaming with a scalable video data synthesis pipeline; ships as a fully open 4B-parameter MLLM that improves general, long-form, and streaming benchmarks.

Introduction

Most video-centric multimodal LLMs trade off generality for compute or hide key components behind partial openness. VideoChat3 addresses both limits by treating model efficiency and dataset breadth as co-design objectives: a spatiotemporal backbone (I3D-ViT) and adaptive frame-resolution strategy reduce per-frame cost, while a scalable synthesis pipeline produces three complementary datasets to broaden domain coverage.

Key Findings
  • Inflated 3D Vision Transformer (I3D-ViT) + Adaptive Frame Resolution — yields lower spatiotemporal compute per token so you can process longer or higher-framerate streams without linear cost increases.
  • Three curated training corpora (VideoChat3-Academic2M, VideoChat3-LV116K, VideoChat3-OL617K) — cover general, long-form, and streaming video regimes so the model generalizes across diverse video types rather than overfitting narrow domains.
  • Competitive efficiency at 4B parameters — matches or outperforms prior open-source video MLLMs with equal or larger parameter counts while reducing inference/training cost, enabling more practical research and deployment.
  • Full openness — training code, strategy, and datasets are released to improve reproducibility and community-driven iteration.
Who it's for & trade-offs

Great fit if you need a single open video MLLM that handles short clips, long videos, and live/streaming inputs with reasonable compute demands; research groups and product teams who value reproducibility will benefit from the released datasets and training recipes. Look elsewhere if your primary goal is highest-accuracy, task-specialized models for niche domains (e.g., medical video), or if you require extreme low-latency on tiny-edge devices—those cases may need task-specific tuning or more aggressive quantization.

Where it fits

Positions as a bridge between heavyweight proprietary video models and lightweight per-task models: useful as a generalist backbone or research baseline for multimodal video tasks, and as a starting point for fine-tuning on long-form and streaming benchmarks.

Information

  • Websitearxiv.org
  • AuthorsXinhao Li, Yuhan Zhu, Xiangyu Zeng, Yuhao Dong, Haoning Wu, Zhiqiu Zhang, Yuandong Yang, Changlian Ma, Qingyu Zhang, Yansong Shi
  • Published date2026/07/16

Categories

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