title: an issue with cvGetCaptureProperty on opencv
body: <p>I have a working opencv code that takes feed from my webcam and displays it. (The code is modified from the one <a href="http://www.iis.uni-stuttgart.de/lehre/ss08/ComputerVision/hellovideo.cpp" rel="nofollow">here</a></p>
  
  <p>The only issue is that when I try to print the frames-per-second value, as</p>
  
  <pre><code>int fps = (int) cvGetCaptureProperty(capture, CV_CAP_PROP_FPS);
  printf ("Frames per Second: %d\n",fps);
  </code></pre>
  
  <p>-1 gets printed.</p>
  
  <p>Another (side) issue is that there appears to be some run time errors/warnings</p>
  
  <pre><code>VIDIOC_QUERYMENU: Invalid argument
  VIDIOC_QUERYMENU: Invalid argument
  select timeout
  HIGHGUI ERROR: V4L2: Unable to get property &lt;unknown property string&gt;(5) - Invalid argument
  HIGHGUI ERROR: V4L: Property &lt;unknown property string&gt;(2) not supported by device
  HIGHGUI ERROR: V4L2: Unable to get property &lt;unknown property string&gt;(1) - Invalid argument
  HIGHGUI ERROR: V4L: Property &lt;unknown property string&gt;(2) not supported by device
  </code></pre>
  
  <p>But the code does what it's supposed to do, ie, display video from the webcam.</p>
  
  <p>Any ideas how to sort out the problems? I am using opencv on Eclipse with CDT on Ubuntu 11.10</p>
  
  <p>Thanks in advance.</p>