利用攝像頭獲取連續影象

1.設定幀數為30fps

2.讀取攝像頭5秒視訊

2.將讀取到的視訊以每5幀採取一幅影象，共計30張，並儲存。

原始碼如下：

#include <iostream>
#include <opencv2/opencv.hpp>

using namespace std;
using namespace cv;

int main()
{
	VideoCapture cap(0);//開啟電腦攝像頭
	if (cap.isOpened())
	  cout << "camera is opened"<< endl;
	else 
	  cout << "camera is not opened" << endl;
	

    bool stop = false;
	Mat frame;

	
	//設定攝像頭解析度640*480 幀率30fps
	cap.set(CV_CAP_PROP_FRAME_HEIGHT, 480);
	cap.set(CV_CAP_PROP_FRAME_WIDTH, 640);
	cap.set(CV_CAP_PROP_FPS, 30.0);

	//儲存視訊格式為avi, 編碼為MJPG
	VideoWriter writer("test0.avi",CV_FOURCC('M', 'J', 'P', 'G'),30, Size(640,480),true);

	//通過總幀數控制拍攝時間，如果為5s的視訊，迴圈5*30次；
	Mat videoPlay;
	int count = 150;
	namedWindow("videoplay", WINDOW_NORMAL);
	while (count)
	{
		cap >> videoPlay;
		writer << videoPlay;
		imshow("videoplay", videoPlay);
		waitKey(30);
		count --;
	}

	VideoCapture cap0("test0.avi");
	if(!cap0.isOpened())
		cout << "no video" << endl;
	Mat frame0;
	int num = 1;
	string filename;
	char temp_file[5];
	string path = "C:\\Users\\Administrator\\Desktop\\my\\pic";//can change the path
	for (int i = 1; ;i++)
	{
		cap0 >> frame0;
		if(frame0.empty())
			break;
		if(i % 5 == 0)
		{
		   _itoa_s(num, temp_file, 4, 10);
		   filename = temp_file;
		   filename = path + filename + ".jpg";
		   num ++;
		  imwrite (filename,frame0);
		}
	   }
	cap0.release();

	//system("pause");

	return 0;

}