Improving Interpretable Embeddings for Ad-hoc Video Search with Generative Captions and Multi-word Concept Bank
Jiaxin Wu, Chong-Wah Ngo, Wing-Kwong Chan
TL;DR
The paper tackles ad-hoc video search (AVS) by addressing two bottlenecks: limited video-text datasets and out-of-vocabulary queries. It introduces three components—a large-scale synthetic pre-training corpus (WebVid-genCap7M), a syntax-driven multi-word concept bank to capture phrase-level relationships, and a systematic study of advanced textual/visual features within an interpretable embedding framework. The integrated approach yields state-of-the-art results on MSRVTT and TRECVid AVS benchmarks, doubling $R@1$ on MSRVTT and delivering xinfAP improvements ranging from $2\%$ to $77\%$, averaging around $20\%$, across eight TRECVid years. These findings demonstrate that combining scalable pre-training, richer concept representations, and modern features significantly enhances both the interpretability and effectiveness of AVS systems.
Abstract
Aligning a user query and video clips in cross-modal latent space and that with semantic concepts are two mainstream approaches for ad-hoc video search (AVS). However, the effectiveness of existing approaches is bottlenecked by the small sizes of available video-text datasets and the low quality of concept banks, which results in the failures of unseen queries and the out-of-vocabulary problem. This paper addresses these two problems by constructing a new dataset and developing a multi-word concept bank. Specifically, capitalizing on a generative model, we construct a new dataset consisting of 7 million generated text and video pairs for pre-training. To tackle the out-of-vocabulary problem, we develop a multi-word concept bank based on syntax analysis to enhance the capability of a state-of-the-art interpretable AVS method in modeling relationships between query words. We also study the impact of current advanced features on the method. Experimental results show that the integration of the above-proposed elements doubles the R@1 performance of the AVS method on the MSRVTT dataset and improves the xinfAP on the TRECVid AVS query sets for 2016-2023 (eight years) by a margin from 2% to 77%, with an average about 20%.
