title: OpenCV 2.4.8 cvCaptureFromAVI loads file, but cv::VideoCapture doesn't
body: <p>I'm using OpenCV 2.4.8 on Windows 7 64. I can load and play my AVI file with the C interface <code>cvCaptureFromAVI</code>, but using the C++ interface <code>cv::VideoCapture</code>, <code>cv::VideoCapture.open()</code> returns always false.</p>
  
  <p>I tried to put <code>ffmpeg</code> (static and shared) in my working folder, same problem. Did I need to recompile OpenCV or am I doing it wrong?</p>
  
  <p>Code with C interface:</p>
  
  <pre><code>IplImage *frame;
  CvCapture *capture = cvCaptureFromAVI("sample.avi");
  if ( capture == NULL )
  {
      std::cout &lt;&lt; "video not ok" &lt;&lt; std::endl;
  }
  else
  {
      std::cout &lt;&lt; "video ok" &lt;&lt; std::endl;
      double videoFPS = cvGetCaptureProperty( capture, CV_CAP_PROP_FPS );        
      while(frame = cvQueryFrame(capture))
      {
          cvShowImage("Video", frame);
          cvWaitKey(1000/videoFPS);
      }
      cvDestroyWindow("Video");
      cvReleaseImage(&amp;frame);
      cvReleaseCapture(&amp;capture);
  }
  </code></pre>
  
  <p>Code with C++ interface:</p>
  
  <pre><code>cv::Mat frame;
  cv::VideoCapture capture;
  cv::namedWindow("Video");
  if(capture.open("sample.avi"))
  {
      std::cout &lt;&lt; "video ok" &lt;&lt; std::endl;
      double videoFPS = capture.get(CV_CAP_PROP_FPS);
      int nbFrames = capture.get(CV_CAP_PROP_FRAME_COUNT);
      for(int i=0;i&lt;nbFrames;i++)
      {
          capture &gt;&gt; frame;
          imshow("Video", frame);
          cv::waitKey(1000/videoFPS);
      }
  }
  else
  {
      std::cout &lt;&lt; "video not ok" &lt;&lt; std::endl;
  }
  </code></pre>
  
  <p>Thank you for your help.</p>