OpenCV setting resolution results failing in reading frames

Question

I've tried to change the resolution on raspicam v2 with my raspberry pi 4 b, but this code gives me false every time I try to read frame... Is there anything I am missing? I can easily read frames without setting those parameters, but then it gives me really poor resolution.

#include "opencv2/opencv.hpp"
using namespace cv;
int main(int argc, char **argv)
{
 VideoCapture cap;
 if (!cap.open(0))
 return 0;
 cap.set(CAP_PROP_FRAME_WIDTH, 1920);
 cap.set(CAP_PROP_FRAME_HEIGHT, 1080);
 cap.set(CAP_PROP_FPS, 1);
 for (;;)
 {
 Mat frame; 
 if(cap.read(frame))
 {
 std::cout << "I'm trying out" << std::endl;
 imwrite("test.jpg",frame);
 return 0;
 } else{
 std::cout << "doesn't went as planned" << std::endl;
 }
 }
 return 0;
}

Answer 1

The problem was in raspi-config, I thought I've enabled the camera through config.txt, but I've not. so when I've got into the interfaces tab and enabled the camera, everything worked perfectly. Thank you guys for help :)