VC-Inspector: Advancing Reference-free Evaluation of Video Captions with Factual Analysis

Shubhashis Roy Dipta, Tz-Ying Wu, Subarna Tripathi


Abstract
We propose VC-Inspector, a lightweight, open-source large multimodal model (LMM) for reference-free evaluation of video captions, with a focus on factual accuracy. Unlike existing metrics that suffer from limited context handling, weak factuality assessment, or reliance on proprietary services, VC-Inspector offers a reproducible, fact-aware alternative that aligns closely with human judgments. To enable robust training and interpretable evaluation, we introduce a systematic approach for generating captions with controllable errors, paired with graded quality scores and explanatory annotations. Experiments show that VC-Inspector achieves state-of-the-art correlation with human judgments, generalizing across diverse domains (e.g., VATEX-Eval, Flickr8K-Expert, and Flickr8K-CF benchmarks) and revealing the potential for caption improvement.
Anthology ID:
2026.acl-long.1552
Volume:
Proceedings of the 64th Annual Meeting of the Association for Computational Linguistics (Volume 1: Long Papers)
Month:
July
Year:
2026
Address:
San Diego, California, United States
Editors:
Maria Liakata, Viviane P. Moreira, Jiajun Zhang, David Jurgens
Venue:
ACL
SIG:
Publisher:
Association for Computational Linguistics
Note:
Pages:
33657–33672
Language:
URL:
https://preview.aclanthology.org/ingest-acl/2026.acl-long.1552/
DOI:
Bibkey:
Cite (ACL):
Shubhashis Roy Dipta, Tz-Ying Wu, and Subarna Tripathi. 2026. VC-Inspector: Advancing Reference-free Evaluation of Video Captions with Factual Analysis. In Proceedings of the 64th Annual Meeting of the Association for Computational Linguistics (Volume 1: Long Papers), pages 33657–33672, San Diego, California, United States. Association for Computational Linguistics.
Cite (Informal):
VC-Inspector: Advancing Reference-free Evaluation of Video Captions with Factual Analysis (Dipta et al., ACL 2026)
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PDF:
https://preview.aclanthology.org/ingest-acl/2026.acl-long.1552.pdf
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