Python camera record video and save to local

from os import mkdir
from os.path import isdir
import datetime
from time import sleep
from threading import Thread
import cv2

def write():
    while cap.isOpened():
        ret, frame = cap.read()
        if ret:     #写入视频文件
            aviFile.write(frame)
    aviFile.release()
    
cap = cv2.VideoCapture(0)       #参数0为笔记本自带摄像头
now = str(datetime.datetime.now())[:19].replace(':', '_')       #当前日期时间，如2019-05-24 23:11:00
dirName = now[:10]      #目录名
tempAviFile = dirName+'\\'+now+'.avi'       #视频文件名
if not isdir(dirName):      #创建目录
    mkdir(dirName)

#创建视频文件
aviFile = cv2.VideoWriter(tempAviFile,cv2.VideoWriter_fourcc('M','J','P','G'),25, (640,480))  #帧速和视频宽度、高度

t=Thread(target=write).start()
input('Press any key to end the recording.')
cap.release()