The following code shows, how to count the video frames in an AVI file.

Example

#include "cv.h"
#include <iostream>
#include "highgui.h"
using namespace std;

int main( int argc, char* argv[] ) {
	CvCapture  *capture = cvCaptureFromAVI( "Megamind.avi");
	cvQueryFrame( capture );
	int nFrames = (int) cvGetCaptureProperty( capture , 
        CV_CAP_PROP_FRAME_COUNT );	
	std::cout<<"frames :"<<nFrames;
	getchar();
	return(0);
}