We introduce a novel self-supervised learning approach to learn representations of videos that are responsive to changes in the motion dynamics. Our representations can be learned from data without human annotation and provide a substantial boost to the training of neural networks on small labeled data sets for tasks such as action recognition, which require to accurately distinguish the motion of objects. We promote an accurate learning of motion without human annotation by training a neural network to discriminate a video sequence from its temporally transformed versions. To learn to distinguish non-trivial motions, the design of the transformations is based on two principles: 1) To define clusters of motions based on time warps of different magnitude; 2) To ensure that the discrimination is feasible only by observing and analyzing as many image frames as possible. Thus, we introduce the following transformations: forward-backward playback, random frame skipping, and uniform frame skipping. Our experiments show that networks trained with the proposed method yield representations with improved transfer performance for action recognition on UCF101 and HMDB51.

本研究提出了一种新颖的自监督学习方法来学习对于动态运动变化有响应的视频表征，通过训练神经网络来区分不同的时间变换的视频序列，使得无需人工标注数据即可准确地识别视频中的不稳定运动并增强神经网络在小数据集上的训练。该方法经过实验证明，可显著提高UCF101和HMDB51上的动作识别的传递性能。

通过识别时间转换进行视频表示学习