中文说明：本人用此代码将avi视频文件逐帧转化成了bmp格式的灰度图片。可以直接使用，希望上传后能对大家有帮助，欢迎相互交流。
English Description：
I used this code to frame-by-frame AVI video files into grayscale images in BMP format. Can be used directly, and we hope everyone has to help upload, welcome to communicate.