树莓派rtsp推流的同时定时抓帧拍照并上传ftp

先做个资料整理，回头再详细写。
参考资料:

1. Mjpeg to jpeg time lapse - Raspberry Pi Forums
2. [Tutorial] Making time-lapse video with Raspberry Pi - Raspberry Pi Forums
3. Capturing a time lapse from an RTSP Stream – My Laboratory
4. Raspberry Pi Zero W as a headless time-lapse camera | Jeff Geerling
5. Achieving high frame rate with a Raspberry Pi camera system – Chris Carey
6. Adding date time stamp to a jpg picture - Raspberry Pi Forums
7. Raspberry Pi MJPEG at ~30fps - lewisroberts.com
8. 【树莓派】树莓派推视频流至上位机,实测延时低至150ms[自带CSI摄像头]
9. 树莓派直播推流—树莓派摄像头推流的几种方式
   10.使用树莓派搭建家庭宠物监控并在B站24小时直播