#include<opencv2\opencv.hpp>
#include <iostream>
#include <stdio.h>
#include<fstream> 

using namespace std;
using namespace cv;

//获取视频中的人脸

int main()
{
 //打开视频文件：其实就是建立一个VideoCapture结构 
 VideoCapture capture("1.mp4");
 //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 << currentFrame << ".jpg";
 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);
 int c = waitKey(1000);
 //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;
}