title: 2 usb cameras not working with opencv
body: <p>I'm working on a project of computer vision and I need to use two cameras using opencv library. I tried this code but with two webcams from USB port it doesn't work while it works if I use one usb camera and the camera of my pc.</p>
  
  <pre><code>CvCapture* capture[2];                      
  
  capture[0] = cvCreateCameraCapture(0);
  capture[1] = cvCreateCameraCapture(1);
  
  if(!capture[0] &amp;&amp; !capture[1])
      printf("Webcam error\n");
  </code></pre>
  
  <p>I'm working on windows 7 on an acer aspire 5742g. Is it a problem of the bus of my computer? The cameras are 2 Philips SPZ2000.
  I tried also to work on the pictures taken by the one of them and from the camera on my pc and when I use the code for calibration and rectification found on the book "Learning opencv" of Bradsky I get a bad result. Can somebody help me?
  Thank you in advance,</p>
  
  <p>Sara</p>