中国科学院自动化研究所机构知识库

Video captioning requires that the model has the abilities of video understanding, video-text alignment, and
text generation. Due to the semantic gap between vision and language, conducting video-text alignment is
a crucial step to reduce the semantic gap, which maps the representations from the visual to the language
domain. However, the existing methods often overlook this step, so the decoder has to directly take the visual
representations as input, which increases the decoder’s workload and limits its ability to generate semantically
correct captions. In this paper, we propose a video-text alignment module with a retrieval unit and an
alignment unit to learn video-text aligned representations for video captioning. Specifically, we firstly propose
a retrieval unit to retrieve sentences as additional input which is used as the semantic anchor between
visual scene and language description. Then, we employ an alignment unit with the input of the video and
retrieved sentences to conduct the video-text alignment. The representations of two modal inputs are aligned
in a shared semantic space. The obtained video-text aligned representations are used to generate semantically
correct captions. Moreover, retrieved sentences provide rich semantic concepts which are helpful for generating
distinctive captions. Experiments on two public benchmarks, i.e., VATEX and MSR-VTT, demonstrate that our method outperforms state-of-the-art performances by a large margin. The qualitative analysis shows
that our method generates correct and distinctive captions.