Video-text retrieval has been a crucial and fundamental task in multi-modal
research. The development of video-text retrieval has been considerably
promoted by large-scale multi-modal contrastive pre-training, which primarily
focuses on coarse-grained or fine-grained contrast. However, cross-grained
contrast, which is the contrast between coarse-grained representations and
fine-grained representations, has rarely been explored in prior research.
Compared with fine-grained or coarse-grained contrasts, cross-grained contrast
calculate the correlation between coarse-grained features and each fine-grained
feature, and is able to filter out the unnecessary fine-grained features guided
by the coarse-grained feature during similarity calculation, thus improving the
accuracy of retrieval. To this end, this paper presents a novel multi-grained
contrastive model, namely X-CLIP, for video-text retrieval. However, another
challenge lies in the similarity aggregation problem, which aims to aggregate
fine-grained and cross-grained similarity matrices to instance-level
similarity. To address this challenge, we propose the Attention Over Similarity
Matrix (AOSM) module to make the model focus on the contrast between essential
frames and words, thus lowering the impact of unnecessary frames and words on
retrieval results. With multi-grained contrast and the proposed AOSM module,
X-CLIP achieves outstanding performance on five widely-used video-text
retrieval datasets, including MSR-VTT (49.3 R@1), MSVD (50.4 R@1), LSMDC (26.1
R@1), DiDeMo (47.8 R@1) and ActivityNet (46.2 R@1). It outperforms the previous
state-of-theart by +6.3%, +6.6%, +11.1%, +6.7%, +3.8% relative improvements on
these benchmarks, demonstrating the superiority of multi-grained contrast and
AOSM.

本篇论文提出了一种名为 X-CLIP 的多层次对比模型，通过 Attention Over Similarity Matrix 模块将多粒度相似度矩阵聚合到实例级别，大幅度提高了视频 - 文本检索的性能表现。在五个常用的视频文本检索数据集上，X-CLIP 相较于之前最先进的模型提升了 6.3％至 11.1％，证明了多层次对比模型和 AOSM 模块的优越性。