OpenCV读取摄像头

#include <opencv2/core.hpp>
#include <opencv2/imgcodecs.hpp>
#include <opencv2/highgui.hpp>
#include <opencv2/imgproc.hpp>
#include <iostream>
using namespace cv;
using namespace std;
void PrintMs(const char *text = "")
{
	static long long last = 0;
	long long cur = getTickCount();
	if (last == 0)
	{
		last = cur;
		return;
	}
	long long ms = 0;
	ms = ((double)(cur - last) / getTickFrequency()) * 1000;
	if (*text != 0)
	{
		printf("%s = %dms\n", text,ms);
	}
	last = getTickCount();
}

int main(int argc, char *argv[])
{
	VideoCapture video;
	video.open(0);
	if (!video.isOpened())
	{
		cout << "open video failed!" << endl;
		getchar();
		return -1;
	}

	cout << "open video success!" << endl;
	namedWindow("video");
	Mat frame;
	for (;;)
	{
		//if (!video.read(frame))
		//{
		//	break;
		//}
		//读帧，解码
		if (!video.grab())
		{
			break;
		}
		//转换颜色格式
		if (!video.retrieve(frame))
		{
			break;
		}
		if (frame.empty()) break;
		imshow("video", frame);
		waitKey(30);
	}
	getchar();



	return 0;
}