This paper addresses the problem of self-supervised video representation learning from a new perspective -- by video pace prediction. It stems from the observation that human visual system is sensitive to video pace, e.g., slow motion, a widely used technique in film making. Specifically, given a video played in natural pace, we randomly sample training clips in different paces and ask a neural network to identify the pace for each video clip. The assumption here is that the network can only succeed in such a pace reasoning task when it understands the underlying video content and learns representative spatio-temporal features. In addition, we further introduce contrastive learning to push the model towards discriminating different paces by maximizing the agreement on similar video content. To validate the effectiveness of the proposed method, we conduct extensive experiments on action recognition and video retrieval tasks with several alternative network architectures. Experimental evaluations show that our approach achieves state-of-the-art performance for self-supervised video representation learning across different network architectures and different benchmarks. The code and pre-trained models are available at \url{https://github.com/laura-wang/video-pace}.

本文提出了一种新的自监督视频表示学习方法，即通过视频速度预测的方法来引导网络学习空间-时间特征，通过对相似视频内容最大化协同一致性来使模型区分不同速度的视频。实验表明，该方法在不同网络结构和数据集上均取得了现有最佳结果。

基于运动预测的自监督视频表示学习