OpenCV读写视频文件

OpenCV提供了VideoCapture类来支持视频读/写。VideoCapture类通过read()函数来获取每一帧，即一个RGB图像。

本文用到的视频traffic.flv，来源于原作者Github，地址为： 
https://github.com/techfort/pycv/tree/master/chapter8/surveillance_demo

OpenCV读取视频并显示

# -*- coding:utf-8 -*-

import cv2

cap = cv2.VideoCapture('video/traffic.flv')

while True:
    ret, frame = cap.read() # 读
    cv2.imshow("capture", frame) # 显示
    if cv2.waitKey(100) & 0xFF == ord('q'): #键盘按键q，退出
        break

OpenCV写入视频

# -*- coding:utf-8 -*-

import cv2

# Step1. 调用VideoCapture构造器
cap = cv2.VideoCapture('video/traffic.flv')
fps = cap.get(cv2.CAP_PROP_FPS)
size = (int(cap.get(cv2.CAP_PROP_FRAME_WIDTH)), int(cap.get(cv2.CAP_PROP_FRAME_HEIGHT)))

# Step2. 改用YUV颜色编码 写入到另一个视频文件中
# 注意，视频文件的后缀改为.avi，由于I420采用YUV颜色编码，只支持.avi格式
writer = cv2.VideoWriter('video/trafficOutput.avi', cv2.VideoWriter_fourcc('I', '4', '2', '0'), fps, size)
ret, frame = cap.read()
while ret:
    writer.write(frame)
    ret, frame = cap.read()


# Step3.读取新的文件
cap = cv2.VideoCapture('video/trafficOutput.avi')
while True:
    ret, frame = cap.read() # 读
    cv2.imshow("capture", frame) # 显示
    if cv2.waitKey(100) & 0xFF == ord('q'): #键盘按键q，退出
        break