How to Display Multi Webcam with QT + OpenCV + Eclipse?

[thaihoangluu]

hi everybody
I am using two Logitech Webcam. But at my first stage I am unable to view image from 2 webcam

i used QT as my platform

I used the openCv function as follows:

CvCapture *cam1;//structure where camera link is stored
CvCapture *cam2;
 cam1 = cvCaptureFromCAM(2);
    cam2 = cvCaptureFromCAM(1);
 
    cvSetCaptureProperty(cam1, CV_CAP_PROP_FRAME_WIDTH, 640);
    cvSetCaptureProperty(cam1, CV_CAP_PROP_FRAME_HEIGHT, 480);
 
    cvSetCaptureProperty(cam2, CV_CAP_PROP_FRAME_WIDTH, 640);
    cvSetCaptureProperty(cam2, CV_CAP_PROP_FRAME_HEIGHT, 480);
 
    cvSetCaptureProperty(cam1, CV_CAP_PROP_FPS, 8);
    cvSetCaptureProperty(cam2, CV_CAP_PROP_FPS, 8);
 
    IplImage *frame1, *frame2;
 
    while(1)
    {
 
        frame1 = cvQueryFrame(cam1);
        frame2 = cvQueryFrame(cam2);
 
        cvShowImage("Left", frame1);
        cvShowImage("Right",frame2);
        char k;
        if(k==27)
            break;
    }
    cvReleaseCapture(&cam1);
    cvReleaseCapture(&cam2);
    cvDestroyAllWindows();

CvCapture *cam1;//structure where camera link is stored
CvCapture *cam2;
 cam1 = cvCaptureFromCAM(2);
    cam2 = cvCaptureFromCAM(1);

    cvSetCaptureProperty(cam1, CV_CAP_PROP_FRAME_WIDTH, 640);
    cvSetCaptureProperty(cam1, CV_CAP_PROP_FRAME_HEIGHT, 480);

    cvSetCaptureProperty(cam2, CV_CAP_PROP_FRAME_WIDTH, 640);
    cvSetCaptureProperty(cam2, CV_CAP_PROP_FRAME_HEIGHT, 480);

    cvSetCaptureProperty(cam1, CV_CAP_PROP_FPS, 8);
    cvSetCaptureProperty(cam2, CV_CAP_PROP_FPS, 8);

    IplImage *frame1, *frame2;

    while(1)
    {

        frame1 = cvQueryFrame(cam1);
        frame2 = cvQueryFrame(cam2);

        cvShowImage("Left", frame1);
        cvShowImage("Right",frame2);
        char k;
        if(k==27)
            break;
    }
    cvReleaseCapture(&cam1);
    cvReleaseCapture(&cam2);
    cvDestroyAllWindows();

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WHY when I Run Program It show Dialog tell me choose 1 in 2 Webcam?????
a.png

But here I get image frames from one camera only.
how can I solve the problem.....Is it the bandwidth problem??
I am using windows 7. Please help me.
Thanks.