how to free the camera - opencv

Question

How can I release the camera when application keeps on running. It is still in on condition. here is the code. I don't know how to release it
#include <cv.h>
#include <highgui.h>
main( int argc, char* argv[] ) {
int i=1;
CvCapture* capture = NULL;
capture = cvCreateCameraCapture( 0 );
IplImage *frames = cvQueryFrame(capture);
while(1) {
if (i==20)
cvReleaseCapture ( &capture );
char c = cvWaitKey(33);
if( c == 27 ) break;
i++;
}
return 0;
}

Answer 1

Your code isn't totally clear so I hope I'm understanding correctly, but I think what you want is something more like this...
#include <cv.h>
#include <highgui.h>
int main( int argc, char* argv[] )
{
int i=1;
CvCapture* capture = NULL;
capture = cvCreateCameraCapture( 0 );
IplImage *frame = cvQueryFrame(capture);
while(1)
{
// if we are on the 20th frame, quit.
if (i==20)
{
cvReleaseCapture ( &capture );
break;
}
// if the user types whatever key 27 corresponds to, quit.
char c = cvWaitKey(33);
if( c == 27 )
{
cvReleaseCapture ( &capture );
break;
}
// do you want to get the next frame? here.
frame = cvQueryFrame( capture );
i++;
}
return 0;
}
Your problem is that you are not breaking after releasing the capture, so you will continue in the loop with a released camera. Also, you had IplImage *frames instead of IplImage *frame. That will only point to a single frame at a time, so I figured renaming it would be helpful for you.