Video I/O Functions in OpenCV

Video Capture

CvCapture* capture = NULL;
IplImage *frame = NULL;
if(is_video_file(input))
  capture = cvCreateFileCapture( input );
else if ( isdigit(input[0]) )
  capture = cvCreateCameraCapture( atoi(input) );
//cvGetCaptureProperty( capture, CV_CAP_PROP_FRAME_WIDTH);
//cvGetCaptureProperty( capture, CV_CAP_PROP_FRAME_HEIGHT);
if(capture)
{
   for(;;)
   {
     if(!frame = cvQueryFrame( capture ))
       continue;//break;
     process_frame(frame);
     if( cvWaitKey( 10 ) >= 0 )
       break;
   }
}
cvReleaseImage( &frame );
cvReleaseCapture( &capture );

Video Writing

CvVideoWriter *writer = cvCreateVideoWriter(
            const char* filename, int fourcc, double fps, CvSize frame_size, int is_color=1);
IplImage *frame = NULL;
if(writer)
{
  for(;;)
  {
    if(!frame = get_frame();
      continue;
    cvWriteFrame(writer, frame);
    if( cvWaitKey( 10 ) >= 0 )
      break;
  }
}
cvReleaseImage( &frame );
cvReleaseVideoWriter( &writer );