Hello world test, capture video frame from V4L2 camera, decode and display it to the monitor by SDL.

跟摄像头连接，并读取和分析MJPEG流，使用SDL显示-Read and process a MJPEG stream using C++

ffmpeg视屏库的C++版本使用，音频和视频的同步，使用SDL作为框架。共8课时的源码（打包），添加到工程中就可以使用。-ffmpeg library C++ screen versions, audio and video synchronization, using SDL as a framework. 8 hours of source (packaged), added to the project can be used.