基于ffmpeg的API，从摄像头采集数据并将其保存为mp4或者avi文件。有详细的中文备注，测试可用。-Ffmpeg' s API to collect data from the camera and save it as mp4 or avi file. Detailed Chinese notes, tests are available.

定义c++类，实现ffmpeg 库解码视频文件-use ffmpeg library to decode video stream by a c++ class