Most online massive open online course platforms (such as China University OCW, Tang Xue Online, Netease Open Class, etc.). ) Support the double-speed playback function of video courses. Users can choose their own playback speed according to their study habits and comprehension ability, and usually provide playback speeds of 0.5 times, 1 times, 1.25 times, 1.5 times, 1.75 times and 2 times. This is very helpful to improve learning efficiency and adapt to the learning rhythm of different students.