Video capture on MacBook

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Better don't use C-style API anymore, it is more verbose, error-prone, no performance benefits and will be deprecated in the future(deprecate c api).

Here is the codes of c++ api, much easier and cleaner(we don't need goto again, because of the power of RAII, c++ programmers rarely need to use goto in their codes).

#include <iostream>

#include <opencv2/core/core.hpp>
#include <opencv2/highgui/highgui.hpp>
#include <opencv2/video/tracking.hpp>

    int main()
    {
    cv::VideoCapture cap;
    cap.open(0);

    if( !cap.isOpened() )
    {
        std::cerr << "***Could not initialize capturing...***\n";
        std::cerr << "Current parameter's value: \n";
        return -1;
    }

    cv::Mat frame;
    while(1){
        cap >> frame;
        if(frame.empty()){
            std::cerr<<"frame is empty"<<std::endl;
            break;
        }

        cv::imshow("", frame);
        cv::waitKey(10);
    }

    return 1;
}

run on MacOSX 10.8.x

Try this, it worked perfectly for me:

#include <iostream>
#include <highgui.h>
#include <opencv2/imgproc/imgproc.hpp>

using namespace std;

#define CAMERA_OUTPUT_WINDOW_NAME "camera-output"

int main(int argc, char **argv)
{
    CvCapture *camCapture;
    int ret = 0;

    if (!(camCapture = cvCaptureFromCAM(CV_CAP_ANY))) {
        cout << "Failed to capture from camera" << endl;

        ret = 1;

        goto exitCameraOpenFailed;
    }

    cout << "Camera opened successfully" << endl;

    cvNamedWindow(CAMERA_OUTPUT_WINDOW_NAME, CV_WINDOW_AUTOSIZE);

    IplImage *cameraFrame;
    int grabFrameRet;

    while (true) {
        if ((cameraFrame = cvQueryFrame(camCapture))) {
            cvShowImage(CAMERA_OUTPUT_WINDOW_NAME, cameraFrame);
        }

        if (cvWaitKey(60) != -1) {
            cout << "Input" << endl;
            break;
        }
    }

    cout << "Done" << endl;

    cvReleaseCapture(&camCapture);
    cvDestroyWindow(CAMERA_OUTPUT_WINDOW_NAME);
exitCameraOpenFailed:
    return ret;
}

I had the same problem and I see that the following code works:

#include <iostream>
#include <highgui.h>
#include <imgproc/imgproc.hpp>

using namespace std;

#define CAMERA_OUTPUT_WINDOW_NAME "camera-output"

int main(int argc, char **argv)
{
    CvCapture *camCapture;
    int ret = 0;

    if (!(camCapture = cvCaptureFromCAM(CV_CAP_ANY))) {
        cout << "Failed to capture from camera" << endl;

        ret = 1;

        goto exitCameraOpenFailed;
    }

    cout << "Camera opened successfully" << endl;

    cvNamedWindow(CAMERA_OUTPUT_WINDOW_NAME, CV_WINDOW_AUTOSIZE);

    IplImage *cameraFrame;
    int grabFrameRet;

    while (true) {
        if ((cameraFrame = cvQueryFrame(camCapture))) {
            cvShowImage(CAMERA_OUTPUT_WINDOW_NAME, cameraFrame);
        }

        if (cvWaitKey(60) != -1) {
            cout << "Input" << endl;
            break;
        }
    }

    cout << "Done" << endl;

    cvReleaseCapture(&camCapture);
    cvDestroyWindow(CAMERA_OUTPUT_WINDOW_NAME);
exitCameraOpenFailed:
    return ret;
}

The cvQueryFrame appears to be non-blocking and if there's no frame to return, it just returns null.