【P14 3-6 】OpenCV Python——视频加载、摄像头调用、视频基本信息获取（宽、高、帧率、总帧数）

P14 3-6

1 读取本地视频

1.1 绝对路径 4种方式

#cap=cv2.VideoCapture('E:\\Python\\opencv-master源码\\opencv-master\\opencv\\轮廓\\video.mp4')
#cap=cv2.VideoCapture("E:\\Python\\opencv-master源码\\opencv-master\\opencv\\轮廓\\video.mp4")
#cap=cv2.VideoCapture('E:/Python/opencv-master源码/opencv-master/opencv/轮廓/video.mp4')
cap=cv2.VideoCapture("E:/Python/opencv-master源码/opencv-master/opencv/轮廓/video.mp4")

1.2 相对路径 4种方式

1.3 读取本地视频

import cv2
from cv2 import WINDOW_NORMAL
import numpy as np# cv2.namedWindow('video',WINDOW_NORMAL)
cap=cv2.VideoCapture("E:/Python/opencv-master源码/opencv-master/opencv/轮廓/video.mp4")while True:ret,frame=cap.read()cv2.imshow('video',frame)key=cv2.waitKey(20)#当按下q键，退出视频，qASCII值=113，Q=81，还可以写成ord('q')#if(key & 0xff ==ord('q')):if(key == 113):breakcv2.destroyWindow()

2 视频基本信息

if(cap.read()):w=cap.get(CAP_PROP_FRAME_WIDTH)h=cap.get(CAP_PROP_FRAME_HEIGHT)fps=cap.get(CAP_PROP_FPS)count=cap.get(CAP_PROP_FRAME_COUNT)print('视频中图像宽度：%d' %(w))print('视频中图像高度：%d' %(w))print('视频的帧率：%d' %(fps))print('视频总帧数：%d' %(count))

3 调用摄像头

import cv2#创建VideoWriter为写多媒体文件
fourcc = cv2.VideoWriter_fourcc(*'MJPG')
vw = cv2.VideoWriter('./out.mp4', fourcc, 25, (1280, 720))#创建窗口
cv2.namedWindow('video', cv2.WINDOW_NORMAL)
cv2.resizeWindow('video', 640, 360)#获取视频设备/从视频文件中读取视频帧
cap = cv2.VideoCapture(0)#判断摄像头是否为打开关态
while cap.isOpened():#从摄像头读视频帧ret, frame = cap.read()if ret == True:#将视频帧在窗口中显示cv2.imshow('video', frame)#重新将窗口设备为指定大小cv2.resizeWindow('video', 640, 360)#写数据到多媒体文件vw.write(frame)#等待键盘事件，如果为q，退出key = cv2.waitKey(1)if(key & 0xFF == ord('q')):breakelse:break#释放VideoCapture
cap.release()#释放VideoWriter
vw.release()#vw.release()
cv2.destroyAllWindows()