[opencv入门笔记] 读视频转图像—读取视频中每一帧图像

#include <opencv2 core="" core="" hpp="">
#include <opencv2 highgui="" highgui="" hpp="">
#include <opencv2 imgproc="" imgproc="" hpp="">
#include <iostream>
using namespace std;
using namespace cv;
int main()
{
//打开视频文件：其实就是建立一个VideoCapture结构  
VideoCapture capture("F:\\6.avi");
//检测是否正常打开:成功打开时，isOpened返回ture  
if (!capture.isOpened())
cout << "fail toopen!" << endl;

//获取整个帧数  
long totalFrameNumber = capture.get(CV_CAP_PROP_FRAME_COUNT);
cout << "整个视频共" << totalFrameNumber << "帧" << endl;

//设置开始帧()  
long frameToStart = 1;
capture.set(CV_CAP_PROP_POS_FRAMES, frameToStart);
cout << "从第" << frameToStart << "帧开始读" << endl;

//设置结束帧  
int frameToStop = 30;
if (frameToStop< frameToStart)
{
cout << "结束帧小于开始帧，程序错误，即将退出！" << endl;
return  - 1;
}
else
{
cout << "结束帧为：第" << frameToStop << "帧" << endl;
}

//获取帧率  
double rate = capture.get(CV_CAP_PROP_FPS);
cout << "帧率为:" << rate << endl;

//定义一个用来控制读取视频循环结束的变量  
bool stop = false;

//承载每一帧的图像  
Mat frame;

//显示每一帧的窗口  
namedWindow("Extractedframe");

//两帧间的间隔时间:  
//int delay = 1000/rate;  
double delay = 1000 / rate;

//利用while循环读取帧  
//currentFrame是在循环体中控制读取到指定的帧后循环结束的变量  
long currentFrame  = frameToStart;

//滤波器的核  
int kernel_size = 3;
Mat kernel  = Mat::ones(kernel_size, kernel_size, CV_32F) / (float)(kernel_size*kernel_size);

while (!stop)
{
//读取下一帧  
if (!capture.read(frame))
{
cout << "读取视频失败" << endl;
return - 1;
}

cout << "正在读取第" << currentFrame << "帧" << endl;
imshow("Extractedframe", frame);

cout << "正在写第" << currentFrame << "帧" << endl;
stringstream str;
str << "sample" << currentFrame  << ".png";
cout << str.str() << endl;
imwrite(str.str(), frame);

//waitKey(intdelay=0)当delay≤ 0时会永远等待；当delay>0时会等待delay毫秒  
//当时间结束前没有按键按下时，返回值为-1；否则返回按键  
int c = waitKey(delay);
//按下ESC或者到达指定的结束帧后退出读取视频  
if ((char)c == 27 || currentFrame > frameToStop)
{
stop  = true;
}
//按下按键后会停留在当前帧，等待下一次按键  
if (c  >= 0)
{
waitKey(0);
}
currentFrame++;

}
//关闭视频文件  
capture.release();
waitKey(0);
return 0;
}
</iostream></opencv2></opencv2></opencv2>