Dual-Channel Localization Networks for Moment Retrieval with Natural Language

According to the given natural language query, moment retrieval aims to localize the most relevant moment in an untrimmed video. The existing solutions for this problem can be roughly divided into two categories based on whether candidate moments are generated: i) Moment-based approach: It pre-cuts the video into a set of candidate moments, performs multimodal fusion, and evaluates matching scores with the query. ii) Clip-based approach: It directly aligns video clips and query with predicting matching scores without generating candidate moments. Both frameworks have respective shortcomings: the moment-based models suffer from heavy computations, while the performance of clip-based models is familiarly inferior to moment-based counterparts. To this end, we design an intuitive and efficient Dual-Channel Localization Network (DCLN) to balance computational cost and retrieval performance. For reducing computational cost, we capture the temporal relations of only a few video moments with the same start or end boundary in the proposed dual-channel structure. The start or end channel map index represents the corresponding video moment's start or end time boundary. For improving model performance, we apply the proposed dual-channel localization network to efficiently encode the temporal relations on the dual-channel map and learn discriminative features to distinguish the matching degree between natural language query and video moments. The extensive experiments on two standard benchmarks demonstrate the effectiveness of our proposed method.