main.cpp

#include <opencv2/opencv.hpp>

/// For the Raspberry Pi 64-bit Bullseye OS

std::string gstreamer_pipeline(int capture_width, int capture_height, int framerate, int display_width, int display_height) {
    return
            " libcamerasrc ! video/x-raw, "
            " width=(int)" + std::to_string(capture_width) + ","
            " height=(int)" + std::to_string(capture_height) + ","
            " framerate=(fraction)" + std::to_string(framerate) +"/1 !"
            " videoconvert ! videoscale !"
            " video/x-raw,"
            " width=(int)" + std::to_string(display_width) + ","
            " height=(int)" + std::to_string(display_height) + " ! appsink";
}

int main()
{
    //pipeline parameters
    int capture_width = 640; //1280 ;
    int capture_height = 480; //720 ;
    int framerate = 15 ;
    int display_width = 640; //1280 ;
    int display_height = 480; //720 ;

    //reset frame average
    std::string pipeline = gstreamer_pipeline(capture_width, capture_height, framerate,
                                              display_width, display_height);
    std::cout << "Using pipeline: \n\t" << pipeline << "\n\n\n";

    cv::VideoCapture cap(pipeline, cv::CAP_GSTREAMER);
    if(!cap.isOpened()) {
        std::cout<<"Failed to open camera."<<std::endl;
        return (-1);
    }

    cv::namedWindow("Camera", cv::WINDOW_AUTOSIZE);
    cv::Mat frame;

    std::cout << "Hit ESC to exit" << "\n" ;
    while(true)
    {
    	if (!cap.read(frame)) {
            std::cout<<"Capture read error"<<std::endl;
            break;
        }
        //show frame
        cv::imshow("Camera",frame);

        char esc = cv::waitKey(5);
        if(esc == 27) break;
    }

    cap.release();
    cv::destroyAllWindows() ;
    return 0;
}