OpenCV学习笔记之课后习题练习2-3

3.使用例2-10中的视频捕捉和存储方法，结合例2-5中的doPyrDown()创建一个程序,使其从摄像机读入视频数据并将缩放变换后的彩色图像存入磁盘。

例2-10中所用的方法虽然能正常运行，但却不能生成存储的视频，百思不得其解。遂参考了一篇博文：blog.csdn.net/jacke121/article/details/54607863

利用文中的方法实现了上述功能。代码如下

 /*ch2_lx2_3.cpp  2017/11/29
   本程序是learning opencv这本书的课后习题练习
   欢迎提出问题一起讨论*/
 #include "cv.h"
 #include "highgui.h"
 using namespace std;
 IplImage* doPyrDown(
     IplImage* in,
     int filter = IPL_GAUSSIAN_5x5)
 {
 assert(in->width% ==  && in->height% == );

  IplImage* out = cvCreateImage(
         cvSize( in->width/, in->height/ ),
         in->depth,
         in->nChannels
     );
     cvPyrDown(in,out);
     return(out);
 };
 int main( int argc, char** argv )
 {
 cvNamedWindow( "Example2",CV_WINDOW_AUTOSIZE);
 cvNamedWindow( "Example3",CV_WINDOW_AUTOSIZE);
 CvCapture* capture = cvCreateFileCapture(argv[]);
 IplImage* frame;
 IplImage* img;
 CvVideoWriter *video=NULL;
 int i=;
 int n;
 while()
 {
   frame = cvQueryFrame( capture );
   img = doPyrDown( frame );
   if( !frame ) break;

   if(i==)
     video=cvCreateVideoWriter("camera.avi",CV_FOURCC('X', 'V', 'I', 'D'),,cvSize(img->width,img->height));
   if(video)
   {
             cout<<"video writer has created!"<<endl;
   }
   n=cvWriteFrame(video,img);
   printf("cvWriteFrame %d\n", n);
   i++;
         cout<<n<<endl;
   cvShowImage( "Example2", frame );
   cvShowImage( "Example3", img );
   char c = cvWaitKey();
   if( c ==  ) break;

     }
     cvReleaseImage(&frame);
     cvReleaseImage(&img);
     cvReleaseVideoWriter(&video);
     cvReleaseCapture( &capture );
     cvDestroyWindow( "Example2" );
     return ;
 }