python3实现视频下载并截图封面

urllib下载文件并保存，cv2打开视频并把第一帧截图

import urllib.request as req
import cv2

def download(url):
    f = req.urlopen(url)
    name="这里自己编.mp4"
    with open(name,'wb') as fd:
        fd.write(f.read())
    return name

def screenShot(name):
    vc = cv2.VideoCapture(name)
    rval,frame = vc.read()
    cv2.imwrite(name.strip('.mp4')+'.jpg',frame)
    vc.release()

if __name__ == '__main__':
    url = '视频url'
    name = download(url)
    screenShot(name)