Functions in OpenCV - c++

Question

Hi I have written the following code in OpenCV. Basically it reads a video from file. Now, I want to create a function to resize the video but I am unsure how to call the "VideoCapture" class from the main function. I have written a sample function to see if it'll read anything but it compiles fine showing stuff from the main function but nothing from the newly created function. Any help? P.S I'm not very experienced, bear with me LOL.
using namespace cv;
using namespace std;
void resize_video(VideoCapture capture);
int main(int argc, char** argv)
{
VideoCapture capture; //the C++ API class to capture the video from file
if(argc == 2)
capture.open(argv[1]);
else
capture.open(0);
if(!capture.isOpened())
{
cout << "Cannot open video file " << endl;
return -1;
}
Mat frame;
namedWindow("display", CV_WINDOW_AUTOSIZE);
cout << "Get the video dimensions " << endl;
int fps = capture.get((int)CV_CAP_PROP_FPS);
int height = capture.get((int)CV_CAP_PROP_FRAME_HEIGHT);
int width = capture.get((int)CV_CAP_PROP_FRAME_WIDTH);
int noF = capture.get((int)CV_CAP_PROP_FRAME_COUNT);
CvSize size = cvSize(width , height);
cout << "Dimensions: " << width << height << endl;
cout << "Number of frames: " << noF << endl;
cout << "Frames per second: " << fps << endl;
while(true)
{
capture >> frame;
if(frame.empty())
break;
imshow("display", frame);
if (waitKey(30)== 'i')
break;
}
//resize_video();
}
void resize_video(VideoCapture capture)
{
cout << "Begin resizing video " << endl;
//return 0;
}

Answer 1

you want to call your function INSIDE the while loop, not after it (too late, program over)
so, it might look like this:
void resize_video( Mat & image )
{
//
// do your processing
//
cout << "Begin resizing video " << endl;
}
and call it like:
while(true)
{
capture >> frame;
if(frame.empty())
break;
resize_video(frame);
imshow("display", frame);
if (waitKey(30)== 'i')
break;
}