CodecCap: High-Fidelity Codec-Inspired Residual Modeling for Dense Video Captioning

Fuente: arXiv
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Main Authors: Lin, Zihan, Deng, Songhe, He, Shuwei, Zhu, Danxiang, Zhang, Dan, Lei, Yishu, Luo, Xianlong, Feng, Shikun, Liu, Rui
Format: Preprint
Published: 2026
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author Lin, Zihan
Deng, Songhe
He, Shuwei
Zhu, Danxiang
Zhang, Dan
Lei, Yishu
Luo, Xianlong
Feng, Shikun
Liu, Rui
author_facet Lin, Zihan
Deng, Songhe
He, Shuwei
Zhu, Danxiang
Zhang, Dan
Lei, Yishu
Luo, Xianlong
Feng, Shikun
Liu, Rui
contents Existing video captioning methods struggle to balance visual fidelity and redundancy: holistic captions are compact but lose fine-grained evidence, whereas segment-wise captions improve coverage but introduce heavy redundancy. We propose CodecCap, a codec-inspired framework for high-fidelity dense video captioning. Analogous to video codecs, CodecCap represents videos using keyframe and residual captions. Keyframe captions exhaustively encode stable visual context, while residual captions capture temporally only localized actions, motions and changes. This effectively preserves fine-grained visual evidence while reducing redundant descriptions. To quantify the fidelity of captions, we introduce VidCapQA, a caption-then-QA benchmark with 1,000 questions across 14 capability dimensions. Results on VidCapQA show that captions directly generated by strong VLMs still miss many visual details, highlighting caption representation as a critical bottleneck. Experiments show that CodecCap significantly surpasses direct captioning with the same underlying VLMs, suggesting keyframe-residual captioning a way for high-fidelity video-language supervision. We further use CodecCap to construct CodecVDC-100K, a large-scale dense captioning dataset with anchor, residual, scene-level, and video-level supervision.
format Preprint
id arxiv_https___arxiv_org_abs_2605_26967
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle CodecCap: High-Fidelity Codec-Inspired Residual Modeling for Dense Video Captioning
Lin, Zihan
Deng, Songhe
He, Shuwei
Zhu, Danxiang
Zhang, Dan
Lei, Yishu
Luo, Xianlong
Feng, Shikun
Liu, Rui
Computer Vision and Pattern Recognition
Existing video captioning methods struggle to balance visual fidelity and redundancy: holistic captions are compact but lose fine-grained evidence, whereas segment-wise captions improve coverage but introduce heavy redundancy. We propose CodecCap, a codec-inspired framework for high-fidelity dense video captioning. Analogous to video codecs, CodecCap represents videos using keyframe and residual captions. Keyframe captions exhaustively encode stable visual context, while residual captions capture temporally only localized actions, motions and changes. This effectively preserves fine-grained visual evidence while reducing redundant descriptions. To quantify the fidelity of captions, we introduce VidCapQA, a caption-then-QA benchmark with 1,000 questions across 14 capability dimensions. Results on VidCapQA show that captions directly generated by strong VLMs still miss many visual details, highlighting caption representation as a critical bottleneck. Experiments show that CodecCap significantly surpasses direct captioning with the same underlying VLMs, suggesting keyframe-residual captioning a way for high-fidelity video-language supervision. We further use CodecCap to construct CodecVDC-100K, a large-scale dense captioning dataset with anchor, residual, scene-level, and video-level supervision.
title CodecCap: High-Fidelity Codec-Inspired Residual Modeling for Dense Video Captioning
topic Computer Vision and Pattern Recognition
url https://arxiv.org/abs/2605.26967