Fast Video Moment Retrieval
This paper targets at fast video moment retrieval (fast VMR), aiming to localize the target moment efficiently and accurately as queried by a given natural language sentence. We argue that most existing VMR approaches can be divided into three modules namely video encoder, text encoder, and cross-modal interaction module, where the last module is the test-time computational bottleneck. To tackle this issue, we replace the cross-modal interaction module with a cross-modal common space, in which moment-query alignment is learned and efficient moment search can be performed. For the sake of robustness in the learned space, we propose a fine-grained semantic distillation framework to transfer knowledge from additional semantic structures. Specifically, we build a semantic role tree that decomposes a query sentence into different phrases (subtrees). A hierarchical semantic-guided attention module is designed to perform message propagation across the whole tree and yield discriminative features. Finally, the important and discriminative semantics are transferred to the common space by a matching-score distillation process. Extensive experimental results on three popular VMR benchmarks demonstrate that our proposed method enjoys the merits of high speed and significant performance.