CODEWITHSUNDEEP
macosopencvvideo-capture
Oliver Chang
Oliver Chang

Reputation: 43

Error when openning built-in Macbook pro camera

I'm trying to read some frames from the built-in camera of a Macbook pro using opencv 4.1.0 with c++. Below is the code I have:

#include "opencv2/opencv.hpp"
#include <opencv2/core/core.hpp>
#include <opencv2/highgui/highgui.hpp>
#include <opencv2/imgcodecs.hpp>
#include <iostream>
#include <unistd.h>

using namespace cv;
using namespace std;


int main(int, char**) {
    VideoCapture cap(0);

    if(!cap.isOpened())
        cerr<<"Error! unable to open camera!";
        return -1;

    cout << "Start grabbing" << endl
    << "Press any key to terminate" << endl;
    Mat frame;
    namedWindow("Live");
    for (;;)
    {
        // wait for a new frame from camera and store it into 'frame'
        cap.read(frame);
        // check if we succeeded
        if (frame.empty()) {
            cerr << "ERROR! blank frame grabbed\n";
            break;
        }
        // show live and wait for a key with timeout long enough to show images
        imshow("Live", frame);
        if (waitKey(5) >= 0)
            break;
    }
    return 0;


}

When calling 

VideoCapture cap(0);

the error I'm getting is:

testApp[11889:464240] +[AVCaptureDevice authorizationStatusForMediaType:]: unrecognized selector sent to class 0x7fff9f79cd50
[ERROR:0] VIDEOIO(AVFOUNDATION): raised unknown C++ exception!

I tried replacing 0 with other indices, but none of them work. Anyone know what is going on?

Upvotes: 1

Views: 850

Answers (2)

Dini_Sarithma
Dini_Sarithma

Reputation: 33

I had the same issue but in python. I wanted to access the webcam and capture images, but continued to get this error. What solved my problem was a simple SMC reset of the macbook.

Upvotes: 0

jojojolin
jojojolin

Reputation: 11

What version of macOS are you running on? I had the exact same issue but in Java. I solved it today by upgrading my OS from High Sierra to Mojave version 10.14 and updating the Xcode command line tools in the terminal using xcode-select --install.

I think the reason we got this problem is that Xcode command line tools - which provides the api (AVFoundation) to access camera on macOS and ios - was too old and therefore not compatible with the newly released OpenCV4.1.0. So my suggestion would be try to update your Xcode command line tools. In my case, I needed to upgrade my OS in order to get a newer version of it.

Upvotes: 1

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