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

using namespace std;
using namespace cv;

//獲取視頻中的人臉

int main()
{
 //打開視頻文件：其實就是建立一個VideoCapture結(jié)構(gòu) 
 VideoCapture capture("1.mp4");
 //檢測是否正常打開:成功打開時，isOpened返回ture 
 if (!capture.isOpened())
  cout << "fail toopen!" << endl;

 //獲取整個幀數(shù) 
 long totalFrameNumber = capture.get(CV_CAP_PROP_FRAME_COUNT);
 cout << "整個視頻共" << totalFrameNumber << "幀" << endl;
 //設置開始幀() 
 long frameToStart = 1;
 capture.set(CV_CAP_PROP_POS_FRAMES, frameToStart);
 cout << "從第" << frameToStart << "幀開始讀" << endl;


 //設置結(jié)束幀 
 int frameToStop = 30;

 if (frameToStop < frameToStart)
 {
  cout << "結(jié)束幀小于開始幀，程序錯誤，即將退出！" << endl;
  return -1;
 }
 else
 {
  cout << "結(jié)束幀為：第" << frameToStop << "幀" << endl;
 }

 //獲取幀率 
 double rate = capture.get(CV_CAP_PROP_FPS);
 cout << "幀率為:" << rate << endl;
 //定義一個用來控制讀取視頻循環(huán)結(jié)束的變量 
 bool stop = false;

 //承載每一幀的圖像 
 Mat frame;

 //顯示每一幀的窗口 
 namedWindow("Extractedframe");

 //兩幀間的間隔時間: 
 //int delay = 1000/rate; 
 double delay = 1000 / rate;


 //利用while循環(huán)讀取幀 
 //currentFrame是在循環(huán)體中控制讀取到指定的幀后循環(huán)結(jié)束的變量 
 long currentFrame = frameToStart;


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

 while (!stop)
 {
  //讀取下一幀 
  if (!capture.read(frame))
  {
   cout << "讀取視頻失敗" << endl;
   return -1;
  }


  cout << "正在讀取第" << currentFrame << "幀" << endl;
  imshow("Extractedframe", frame);

  cout << "正在寫第" << currentFrame << "幀" << endl;
  stringstream str;
  str << currentFrame << ".jpg";
  cout << str.str() << endl;
  imwrite(str.str(), frame);

  //waitKey(intdelay=0)當delay≤ 0時會永遠等待；當delay>0時會等待delay毫秒 
  //當時間結(jié)束前沒有按鍵按下時，返回值為-1；否則返回按鍵 
  //int c = waitKey(delay);
  int c = waitKey(1000);
  //按下ESC或者到達指定的結(jié)束幀后退出讀取視頻 
  if ((char)c == 27 || currentFrame > frameToStop)
  {
   stop = true;
  }
  //按下按鍵后會停留在當前幀，等待下一次按鍵 
  if (c >= 0)
  {
   waitKey(0);
  }
  currentFrame++;

 }
 //關閉視頻文件 
 capture.release();
 waitKey(0);
 return 0;
}