通过cv2读取视频，并在视频上画框

该教程适合做个十几秒的demo，先通过opencv读取视频流并将图片每帧都保存下来，然后在图片上通过labelImg软件进行画框（打标签），并将生成的xml文件保存到同一目录下。

#! encoding: UTF-8

import os
from os import path
import xml.etree.cElementTree as ET 
import cv2

videos = '1.mp4' # 视频路径

cap = cv2.VideoCapture(videos)
count = 0

 while True:
    _, frame = cap.read()
    cv2.imwrite(str(count) + '.jpg', frame)
    xml_file = os.path.join(str(count)+'.xml')
   
    if os.path.exists(xml_file):
        tree = ET.parse(xml_file) 
        root = tree.getroot() 
        object_set = root.findall('object')
        object_bbox = list()
        for Object in object_set:
            bbox = Object.find('bndbox')
            x1 = int(bbox.find('xmin').text.split('.')[0])
            y1 = int(bbox.find('ymin').text.split('.')[0])
            x2 = int(bbox.find('xmax').text.split('.')[0])
            y2 = int(bbox.find('ymax').text.split('.')[0])
            obj_bbox = [x1, y1, x2, y2] 
            cv2.rectangle(frame, (x1, y2), (x2, y1), (0, 0, 255), 2)
            frame = frame
    else:
        frame = frame
    cv2.imshow('res', frame)
    c = cv2.waitKey(5) & 0xff
    if c == 27:
        cap.release()
        break
    count += 1