> int main()
> {
> cv::VideoCapture cap(1); //if(!cap.isOpened()) throw std::runtime_error(“Can’t open camera!”);
> cv::Mat frame; // = cv::Mat::zeros(640, 480, CV_8U);
> cv::namedWindow(“Test”);
> while(true) {
> cap >> frame;
> cv::imshow(“Test”, frame);
> ```
> if(cv::waitKey(20) == 27) break;
> }
>
> std::cout << "Hello, World!" << std::endl;
> return 0;
>
> ```
> }
>
> `
> **CMakeLists.txt**
>
> `
>
> cmake_minimum_required(VERSION 3.17)
> project(Test)
> set(CMAKE_CXX_STANDARD 14)
> find_package(OpenCV REQUIRED)
> #message(${CMAKE_MODULE_PATH})
> include_directories({OpenCV_INCLUDE_DIRS})
> #set(OpenCV_LIB_PATH "{OpenCV_DIR}/lib")
> add_executable(Test main.cpp)
> target_link_libraries(Test ${OpenCV_LIBS})
>
> `
>
> _"OpenCV/x64/mingw/bin"_ is in PATH!
---
### Author:  [@saqib](https://forum.opencv.org/u/saqib)
#### Post date: [September 20, 2023, 6:41am UTC](https://forum.opencv.org/t/mingw-build-error-opencv-4-8-0/14597/6 "2023-09-20T06:41:27Z")
I would just like to build modules separately because opencv\_world is just too large to ship with my little projects that use at max two libraries, so if you can help with that i would be pleased, because my system is slow it already took me freaking **8\*\*hours** to build, only to realize it combined all libs into one.
---
### Author:  [@berak](https://forum.opencv.org/u/berak)
#### Post date: [September 20, 2023, 6:44am UTC](https://forum.opencv.org/t/mingw-build-error-opencv-4-8-0/14597/7 "2023-09-20T06:44:21Z")
> [@saqib](#):
>
> if(!cap.isOpened())
indeed, you must check this ! and this:
> [@saqib](#):
>
> cap \>\> frame;
```
if (frame.empty())) // ALARM !
```
most probably, you capture did not open, try index 0 instead
---
### Author:  [@saqib](https://forum.opencv.org/u/saqib)
#### Post date: [September 20, 2023, 11:03am UTC](https://forum.opencv.org/t/mingw-build-error-opencv-4-8-0/14597/8 "2023-09-20T11:03:57Z")
It worked, for some reason Clion shell couldn’t see Environment variables thats why it was crashing, however my question remains same can i build with slight change to config without building it from scratch, i tried modifying Makefile and Cmake files but they are just too many. regenerating obviously starts building from very start.
---
### Author:  [@berak](https://forum.opencv.org/u/berak)
#### Post date: [September 20, 2023, 11:14am UTC](https://forum.opencv.org/t/mingw-build-error-opencv-4-8-0/14597/9 "2023-09-20T11:14:14Z")
> [@saqib](#):
>
> I would just like to build modules separately
easy:
```
cmake -DBUILD_opencv_world=OFF
```
> [@saqib](#):
>
> thats why it was crashing,
i’m afraid, you’re still making wrong guesses.
if the video capture does not open, it’s because of wrong user supplied params (id, backend) _at runtime_, it’s not a linking problem
---
### Author:  [@saqib](https://forum.opencv.org/u/saqib)
#### Post date: [September 20, 2023, 11:16am UTC](https://forum.opencv.org/t/mingw-build-error-opencv-4-8-0/14597/10 "2023-09-20T11:16:12Z")
Thanks that really helped… yes I got that crashing part under control now.