if cv2.waitKey(1) & 0xff == ord('q'):break的理解

v2.waitKey(1)
1爲參數，單位毫秒ms，表示讀幀間隔時間
ord(’ ')

將字符轉化爲對應的整數（ASCII碼）

關於0xFF

on some systems, waitKey() may return a value that encodes more than just the ASCII keycode. (A bug is known to occur on Linux when OpenCV uses GTK as its backend GUI 
library.) On all systems, we can ensure that we extract just the SCII keycode by reading the last byte from the return value like this: 
keycode = cv2.waitKey(1) o
if keycode != -1: 
keycode &= 0xFF

感謝這些大哥的博客幫助：
https://www.jianshu.com/p/30c40d7ce5dc
https://www.jianshu.com/p/b0d3221b0d81
https://blog.csdn.net/zhaowei5210/article/details/70920711