Question

I have a very simple program on OpenCV:

#include <cv.h>
#include <cxcore.h>
#include <highgui.h>

using namespace std;

void showVideo(CvCapture *video)
{
    int width = (int) cvGetCaptureProperty(video, CV_CAP_PROP_FRAME_WIDTH);
    int height = (int) cvGetCaptureProperty(video, CV_CAP_PROP_FRAME_HEIGHT);
    //int fps = (int) cvGetCaptureProperty(video, CV_CAP_PROP_FPS);
    IplImage* frame = cvCreateImage(cvSize(width, height), 8, 1);
    cvNamedWindow("Showing Video:", 0);
    while (true)
    {
        frame = cvQueryFrame(video);
        cvShowImage("Showing Video:", frame);
        cvWaitKey(10);
    }
    //cvDestroyWindow("Showing Video:");
    //cvReleaseImage(&frame);
}
int main()
{
    CvCapture *video = cvCaptureFromCAM(CV_CAP_ANY);
    showVideo(video);
    return 0;
}

I want to have a char ch; and something like this while(ch != 'q') then it still plays the video. There is some ways such as kbhit() or getch() but they are not standard and I want something that whenever the ‘q’ key is pressed, then the showing the video will finish, otherwise video showing will be still running.

How can I do this job?

Answer 1

cvWaitKey() returns 0 if no key was pressed in the allotted time or the key code if a key is pressed. Change your call to cvWaitKey() to test the return value like this:

chr = cvWaitKey(10);
if (chr == 'q')
    break;