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Video capturing with OpenCV

ebnhuseyin
ebnhuseyin asked
on
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Last Modified: 2011-10-03
I found a simple code on the net about video capturing with opencv functions. However, when i compiled it, it didnt work, cvQueryFrame didnt grab a frame. Actually my camera doesnt a usb camera just connect the pc through DV Capture + Tv Tuner card.
Doesnt OpenCV support Microsoft DV camera VCR driver or do you have any idea about how to correct or change following code?


#include "stdafx.h"
//---------------------------------------------------------
//Open Source Computer Vision Library
//File Name : sample.cpp
//   OS     : WindowsXP
//Library   : OpenCV for MS-Windows ƒÀ4a
// Camera   : USBcamera PMC-30
// Auther   : NAKANO Michiki
//Time-stamp:<November 02, 2004; 22:18>
//---------------------------------------------------------

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


IplImage* src = NULL;      


int _tmain(int argc, _TCHAR* argv[])
{


  int key;      
  CvCapture* capture = NULL;

 
  if(NULL==(capture = cvCaptureFromCAM(-1)))
  {
    printf("\nError on cvCaptureFromCAM");
    return -1;
  }

  //-----
  cvNamedWindow("Capture", CV_WINDOW_AUTOSIZE);
  cvNamedWindow("Capture2", CV_WINDOW_AUTOSIZE);
 
  cvMoveWindow("Capture", 50, 50);
  cvMoveWindow("Capture2", 320, 50);
 
  for(;;){
 
    if(NULL==(src=cvQueryFrame(capture))){
      printf("\nError on cvQueryFrame");
      break;
    }

   
    cvShowImage("Capture", src);

   
    key = cvWaitKey(10);
   
    if(key==0x1b)
      break;
  }
 
  cvReleaseCapture(&capture);
  cvDestroyWindow("Capture");

  return 0;

}
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Dariusz DziaraProgrammer

Commented:
I found info that WDM video sources are mapped to VFW through VFW-to-WDM mapper. This shows as "Microsoft WDM Image Capture" VFW driver as enumerated by capGetDriverDescription() function. If you have more than one such source (WDM) you can switch them with capDlgVideoSource() macro in VFW application.

Theoretically it should work. You can use simple VFW application to select different source for "Microsoft WDM Image Capture" driver - i.e. switch between camera and TV tuner.

Author

Commented:
At the begining i had two camera system, but i uninstalled to usb one to avoid confusion. Now i have only one camera in my system connected trough DV Capture + Tv Tuner card.  How can i write a VFM application with opencv for it. Is there any simplest way

On the other hand i can watch the preview video using DirectX AMCap program. Is that meaning it has VFW driver?

Author

Commented:
Moreover,
At that line " capture = cvCaptureFromCAM(-1) ", function doesnt return  NULL value. when the program comes the line "if(NULL==(src=cvQueryFrame(capture)))" error occurs.  Actually its not a error, cvQueryFrame returns NULL value.

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