说明：  这段代码可以选择一个或多个视频，根据视频名称和帧的序号对图片命名。设定的只能选择avi格式，至于其它格式的视频你可以改改代码的第一句试试
(This code can select one or more video frames based on video name and serial number of the picture naming. Setting can only choose avi format, as other video formats you can change the first sentence to try to change the code)