adding openCV Video to QT Widget

mjv817

Hey Folks,

Having a bit of an issue getting a video to display in a QT Widget.

I can get an openCV window to run/function and display video from my webcam just fine,but when I execute a program the openCV window is the only part the will open until I terminate the webcam loop. Once the webcam is disabled my QT GUI will pop up like normal.

Below is a copy of my VideoCapture example and a part of my MainWindow Class.

void VideoHeader::videoCap()
{

    Mat frame;
    VideoCapture cap;

    cap.open(0);
    if(!cap.isOpened())
    {
        cerr << "ERROR! Unable to open camera\n";
    }

    cout << "Start grabbing" << endl;



    for(;;)
    {
        cap.read(frame);
        if(frame.empty())
        {
            cerr << "ERROR! Blank frame grabbed\n";
            break;
        }
        //convertMat(frame);
        //imshow("Live", frame);

        /*
        if(waitKey(5) >= 0)
            break;
        */



    }


}```

MainWindow::MainWindow() : textEdit(new QTextEdit)
{

//createOpenCVWindow();
createCentralWindow();
createDockingWindow_One();
VideoHeader newVideo;
//videoCap();
//createDockingWindow_Two();

}

SGaist

Hi,

That's because you are creating an infinite loop that doesn't let Qt's event loop run.

This post describes an interesting way of using OpenCV capture with a Qt GUI.

Hope it helps

mjv817

Thanks for the response! That link has lead me down the right path I believe. Using QThread to run the VideoCapture function portion and it appears to be working somewhat properly now.

SGaist

Great !

Since you have it working now, please mark the thread as solved using the "Topic Tools" button so that other forum users may know a solution has been found :)