opencv python基本操作

Python usage
crop frame:

croppedframe = frame[ymin:ymax, xmin:xmax]

resize frame:

reszframe = cv2.resize(frame, (size, size))

read video:
初始化

vid = cv2.VideoCapture(videoname)  

读取方式：

vid.set(read_mode, num or second)
numoframes = vid.get(cv2.CAP_PROP_FRAME_COUNT)
ret, frame = vid.read()	

read_mode:
cv2.CV_CAP_RPOP_POS_MSEC: 按秒
cv2.CV_CAP_PROP_POSE_FRAMES： 按帧数，从0开始