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opencv3/C++实现视频读取、视频写入

yipeiwu_com5年前 (2020-03-06)Python基础

视频读取

视频读取，主要利用VideoCapture类下的方法打开视频并获取视频中的帧，具体示例如下：

#include<iostream>
#include<opencv2/opencv.hpp>
using namespace cv;

int main()
{
  VideoCapture capture;
  Mat frame;
  frame= capture.open("E:/image/a1.avi");
  if(!capture.isOpened())
  {
    printf("can not open ...\n");
    return -1;
  }
  namedWindow("output", CV_WINDOW_AUTOSIZE);

  while (capture.read(frame))
  {
    imshow("output", frame);
    waitKey(10);
  }
  capture.release();
  return 0;
}

capture.open()的参数为0时为读取摄像头：

frame= capture.open(0);

视频写入

通过摄像头获取视频，然后通过capture.get(CV_CAP_PROP_FRAME_WIDTH), capture.get(CV_CAP_PROP_FRAME_HEIGHT)获取当前帧的宽度和高度，创建一个VideoWriter类对象writer进行视频的写入。

写入前可进行视频的简单处理。

#include<iostream>
#include<opencv2/opencv.hpp>
using namespace cv;

int main()
{
  VideoCapture capture;
  capture.open(0);
  if(!capture.isOpened())
  {
    printf("can not open ...\n");
    return -1;
  }

  Size size = Size(capture.get(CV_CAP_PROP_FRAME_WIDTH), capture.get(CV_CAP_PROP_FRAME_HEIGHT));
  VideoWriter writer;
  writer.open("E:/image/a2.avi", CV_FOURCC('M', 'J', 'P', 'G'), 10, size, true);

  Mat frame, gray;
  namedWindow("output", CV_WINDOW_AUTOSIZE);

  while (capture.read(frame))
  {
    //转换为黑白图像
    cvtColor(frame, gray, COLOR_BGR2GRAY); 
    //二值化处理 
    threshold(gray, gray, 0, 255, THRESH_BINARY | THRESH_OTSU);
    cvtColor(gray, gray, COLOR_GRAY2BGR);
    imshow("output", gray);
    writer.write(gray);
    waitKey(10);
  }

  waitKey(0);
  capture.release();
  return 0;
}