How to rotate image in my camera's video? [closed]

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I want to capture video frm my camera and rotate it at the same times and i've writing the program. But it has 1 error My written program is as below:

#include "opencv2/opencv.hpp"
#include "iostream"
#include "opencv2/imgproc/imgproc.hpp"
using namespace cv;
using namespace std;

int main(int argc, char* argv)
{
    VideoCapture camera(0);

    if (!camera.isOpened())
        return -1;
    int iAngle = 180;
    const char* OriginalWindowName = "Original Video";
    namedWindow(OriginalWindowName,1 );
    const char* RotatingWindowName = "Rotated Video";
    namedWindow(RotatingWindowName, 1);
    createTrackbar("Angle", RotatingWindowName, &iAngle, 360);
  while (1)
    {
        Mat3b frame;
        camera >> frame;
        imshow("video", frame);
        if (waitKey(30) == 's')
        {
            break;
        }
        Mat matOriginalFrame;
        bool bSuccess = cap.read(matOriginalFrame);
        if (!bSuccess)
        {
            cout << "Cannot read the frame from video file" << endl;
            break;

        }
        imshow(OriginalWindowName, matOriginalFrame);
        Mat matRotation = getRotationMatrix2D(Point(matOriginalFrame.cols / 2, matOriginalFrame.rows / 2), (iAngle - 180), 1);
        Mat matRotatedFrame;
        warpAffine(matOriginalFrame, matRotatedFrame, matRotation, matOriginalFrame.size());
        imshow(RotatingWindowName, matRotatedFrame);
        if (waitKey(30) == 27)
        {
            cout << "esc key is pressed by user" << endl;
            break;
        }

    }
  return 0;
}

The error is at the line bool bSuccess = cap.read(matOriginalFrame); it said The identifier "cap" is not defined How can i fix this problem? thank you