OpenCV Learning: 第2章视频写入遇到的问题

#include "stdafx.h"
#include "cv.h"
#include "highgui.h"

int main( ) {
CvCapture* capture = cvCaptureFromFile( "E:\\test.avi" );
if (!capture)
{printf("unable to load a video");
cvWaitKey(0);
exit(0);
}
cvNamedWindow("haha", 1);
IplImage* frame;
double fps = cvGetCaptureProperty (
capture,
CV_CAP_PROP_FPS);
printf("fps=%d n",(int)fps);
/*
Here with the help cvGetCaptureproperty we are trying to acquire the widht and height of the video… and store it in CvSize structure….Please do not get overwhelmed…
treat CvSize structure as a normal easy to understand structure and read on…
*/
CvSize size = cvSize((int)cvGetCaptureProperty( capture, CV_CAP_PROP_FRAME_WIDTH),
(int)cvGetCaptureProperty( capture, CV_CAP_PROP_FRAME_HEIGHT)
);
printf("frame (w, h) = (%d, %d)n",size.width,size.height);
/*Creating the Video writer If you do not know about the Video writer study this post and come back to tis line*/
CvVideoWriter  *writer = cvCreateVideoWriter(
"partofvideo.avi",/*filename*/
CV_FOURCC('X','V','I','D'), /*codec type*/
fps,
size,
1
);
IplImage* gray_frame = cvCreateImage(size, IPL_DEPTH_8U, 1);
int counter=0;
while( (frame=cvQueryFrame(capture)) != NULL ) {
counter++;
/*discard all the frames before a certain time and accept the frames in a certain time period and write the frames in the new video*/
cvConvertImage(frame, gray_frame, 0);
printf("entered\n");
cvWriteFrame( writer, gray_frame );

cvShowImage("haha", gray_frame);
if((cvWaitKey(100)) == 27)
break;
}
cvReleaseImage(&frame);
cvReleaseImage(&gray_frame);
cvReleaseVideoWriter( &writer );
cvReleaseCapture( &capture );
cvDestroyWindow("haha");
return 0;
}