Fragment.java

public class TabLive extends Fragment implements  CameraBridgeViewBase.CvCameraViewListener2 {
 ...
 
 @Override
    public View onCreateView(LayoutInflater inflater, @Nullable ViewGroup container, @Nullable Bundle savedInstanceState) {
        View v =inflater.inflate(R.layout.tab_live,container,false);

        mOpenCvCameraView = (CameraBridgeViewBase) v.findViewById(R.id.live_camera_frame);
        mOpenCvCameraView.setCvCameraViewListener(this);
        
        ...
    }
}