一、与摄像头建立连接
1.RTSP格式
//格式rtsp://username:password@<address>:<port>/Streaming/Channels<id>?channel=1&subtype=0//举例rtsp://admin:admin123456@10.0.10.21:554/cam/realmonitor?channel=1&subtype=0
2.测试连接可行性（使用VLC media player）
1.打开VLC
2.打开网络串流（Ctrl + N)
3.输入rtsp://admin:admin123456@10.0.10.21:554/cam/realmonitor?channel=1&subtype=0，点击播放
4.观察是否有监控画面显示。如果没有，检查大华摄像头是否正常启动；如果有监控画面，说明连接可正常建立，获取大华监控画面具有可行性。
二、连接、接收视频帧
1.rtsp地址
std::string url = "rtsp://admin:admin123456@10.0.10.21:554/cam/realmonitor?channel=1&subtype=0";
2.声明
cv::VideoCapture m_capture; //!< 用于帧捕获的对象cv::Mat m_frame; //!< 捕获到的帧cv::Mat m_buffFrame; //!< 缓存的非空白帧
3.建立连接
void DefaultCamera::init(){try{m_capture.open(url);}catch (const std::exception &e){std::cerr << e.what() << std::endl;}if (m_capture.isOpened()){std::cout << "[DefaultCamera] is opened" << std::endl;m_run = true;// 捕获成功, 于是开始实时读取帧数据std::thread _t(&DefaultCamera::readFrame, this);_t.detach();}else{std::cout << "[DefaultCamera] is not opened" << std::endl;}}
4.接收帧
void DefaultCamera::readFrame(){bool _error = m_capture.read(m_frame);if (m_frame.empty())m_frame = m_buffFrame;elsem_buffFrame = m_frame;}
5.提供接口
cv::Mat DefaultCamera::getCurrentFrame(){return m_frame.clone();}
三、将视频帧转成图片
1.调用接口获取最新帧
QImage exit_image = cameraToImage(exitCamera->getCurrentFrame());
2.帧转成图片
QImage EntranceExitCamera::cameraToImage(const cv::Mat& cvImg){QImage qImg;int _type = cvImg.type();//int channels = cvImg.channels();if (_type == CV_8UC3) //三通道彩色图像{cv::cvtColor(cvImg, cvImg, CV_BGR2RGB);qImg = QImage((const unsigned char*)(cvImg.data), cvImg.cols, cvImg.rows, static_cast<int>(cvImg.step), QImage::Format_RGB888).copy();}else if (_type == CV_8UC1) //单通道灰度图{qImg = QImage((const unsigned char*)(cvImg.data), cvImg.cols, cvImg.rows, static_cast<int>(cvImg.step), QImage::Format_Grayscale8).copy();}else //默认按照四通道RGBA处理{cv::cvtColor(cvImg, cvImg, CV_BGRA2RGBA);qImg = QImage((const unsigned char*)(cvImg.data), cvImg.cols, cvImg.rows, static_cast<int>(cvImg.step), QImage::Format_RGBA8888).copy();}return qImg;}
