MARS: What Retrieval Signals Are Hidden in Multimodal Large Language Models for Text-Video Retrieval?

Uicheol Jung, Juyoung Hong, Geuntaek Lim, Yukyung Choi


Abstract
Text-video retrieval requires representations that can distinguish videos with similar scenes, actions, and temporal patterns. Recent multimodal large language models have been adapted as embedding models, but they often represent each input using a single token from the final layer. This can compress diverse video-text cues into a single vector and limit fine-grained retrieval. To address this limitation, we propose MARS, a multi-layer and multi-slot embedding framework for text-video retrieval. MARS constructs multiple adaptive representation slots by combining hidden states from different decoder layers, compares corresponding text and video slots, and aggregates their similarities for retrieval. To better handle confusing candidates, we further introduce a hard-negative-aware slot specialization objective that encourages the slots to capture discriminative matching cues. Experiments on four text-video retrieval benchmarks show that MARS achieves state-of-the-art results in both direct similarity-based retrieval and reranking settings. Ablation studies and analyses demonstrate that multi-layer fusion, multiple slots, and hard-negative-aware slot specialization provide complementary gains.
Anthology ID:
2026.emnlp-main.1347
Volume:
Proceedings of the 2026 Conference on Empirical Methods in Natural Language Processing
Month:
October
Year:
2026
Address:
Budapest, Hungary
Editors:
Hung-Yi Lee, Sunipa Dev, Jessy Li, Desmond Elliott
Venue:
EMNLP
SIG:
SIGDAT
Publisher:
Association for Computational Linguistics
Note:
Pages:
30716–30730
Language:
URL:
https://aclanthology.org/2026.emnlp-main.1347/
DOI:
Bibkey:
Cite (ACL):
Uicheol Jung, Juyoung Hong, Geuntaek Lim, and Yukyung Choi. 2026. MARS: What Retrieval Signals Are Hidden in Multimodal Large Language Models for Text-Video Retrieval?. In Proceedings of the 2026 Conference on Empirical Methods in Natural Language Processing, pages 30716–30730, Budapest, Hungary. Association for Computational Linguistics.
Cite (Informal):
MARS: What Retrieval Signals Are Hidden in Multimodal Large Language Models for Text-Video Retrieval? (Jung et al., EMNLP 2026)
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https://aclanthology.org/2026.emnlp-main.1347.pdf