opencv摄像头用法

c++打开摄像头： 

#include
#include
#include
#include
using namespace std;
using namespace cv;
 
int main()
{
	//定义VideoCapture对象选择摄像头
	VideoCapture capture(0);
	//判断是否出错
	if (!capture.isOpened())
	{
		cout << "some thing wrong" << endl;
		system("pause");
		return -1;
	}
	//获取视频相关信息---分辨率（宽、高）
	int  frameHeight = capture.get(CV_CAP_PROP_FRAME_HEIGHT);
	int frameWidth = capture.get(CV_CAP_PROP_FRAME_WIDTH);
	cout << "this video is :" << frameWidth << "*" << frameHeight << endl;
	//定义writer对象
	VideoWriter outputVideo;
	outputVideo.open("save.avi", -1, 25.0, Size(frameWidth, frameHeight), true);
	//判断open writer对象是否出错
	if (!outputVideo.isOpened()){
		cout << "fail to open the videowriter" << endl;
		system("pause");
		return -1;
	}
 
	//循环读取一帧
	Mat frameImg;
	long nCount = 1;
	while (1){
		//输出当前帧数
		cout << "Current frame" << nCount << endl;
		capture >> frameImg;
		//判断是否读完
		if (!frameImg.empty()){
			imshow("frame", frameImg);
		}
		else{
			break;
		}
		//按Q退出
		if (char(waitKey(40) == 'q')){
			break;
		}
		outputVideo << frameImg;//将该帧写入文件
		nCount++;
	}
	//释放摄像头
	capture.release();
	return 0;
}