MABAN: Multi-Agent Boundary-Aware Network for Natural Language Moment Retrieval.

The amount of videos over the Internet and electronic surveillant cameras is growing dramatically, meanwhile paired sentence descriptions are significant clues to select attentional contents from videos. The task of natural language moment retrieval (NLMR) has drawn great interests from both academia and industry, which aims to associate specific video moments with the text descriptions figuring complex scenarios and multiple activities. In general, NLMR requires temporal context to be properly comprehended, and the existing studies suffer from two problems: (1) limited moment selection and (2) insufficient comprehension of structural context. To address these issues, a multi-agent boundary-aware network (MABAN) is proposed in this work. To guarantee flexible and goal-oriented moment selection, MABAN utilizes multi-agent reinforcement learning to decompose NLMR into localizing the two temporal boundary points for each moment. Specially, MABAN employs a two-phase cross-modal interaction to exploit the rich contextual semantic information. Moreover, temporal distance regression is considered to deduce the temporal boundaries, with which the agents can enhance the comprehension of structural context. Extensive experiments are carried out on two challenging benchmark datasets of ActivityNet Captions and Charades-STA, which demonstrate the effectiveness of the proposed approach as compared to state-of-the-art methods. The project page can be found in https://mic.tongji.edu.cn/e5/23/c9778a189731/page.htm.