When and What: Diffusion-Grounded VideoLLM with Entity Aware Segmentation for Long Video Understanding

• URL: http://arxiv.org/abs/2508.15641v1
• Date: Thu, 21 Aug 2025 15:12:14 GMT
• Title: When and What: Diffusion-Grounded VideoLLM with Entity Aware Segmentation for Long Video Understanding
• Authors: Pengcheng Fang, Yuxia Chen, Rui Guo,
• Abstract summary: We present Grounded VideoDiT, a Video LLM designed to overcome limitations by introducing three key innovations.<n>First, a Diffusion Temporal Latent (DTL) encoder enhances boundary sensitivity and maintains temporal consistency.<n>Second, object grounded representations explicitly bind query entities to localized visual evidence, strengthening alignment.<n>Third, a mixed token scheme with discrete temporal timestamp tokens provides explicit modeling, enabling fine grained temporal reasoning.
• Score: 12.410012029024342
• License: http://arxiv.org/licenses/nonexclusive-distrib/1.0/
• Abstract: Understanding videos requires more than answering open ended questions, it demands the ability to pinpoint when events occur and how entities interact across time. While recent Video LLMs have achieved remarkable progress in holistic reasoning, they remain coarse in temporal perception: timestamps are encoded only implicitly, frame level features are weak in capturing continuity, and language vision alignment often drifts from the entities of interest. In this paper, we present Grounded VideoDiT, a Video LLM designed to overcome these limitations by introducing three key innovations. First, a Diffusion Temporal Latent (DTL) encoder enhances boundary sensitivity and maintains temporal consistency. Second, object grounded representations explicitly bind query entities to localized visual evidence, strengthening alignment. Third, a mixed token scheme with discrete temporal tokens provides explicit timestamp modeling, enabling fine grained temporal reasoning. Together, these designs equip Grounded VideoDiT with robust grounding capabilities, as validated by state of the art results on Charades STA, NExT GQA, and multiple VideoQA benchmarks.

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