title: OpenCV wont' capture from MacBook Pro iSight
body: <p>Since a couple of days I can't open my iSight camera from inside an opencv application any more. <code>cap = cv2.VideoCapture(0)</code> returns, and <code>cap.isOpened()</code> returns <code>true</code>. However, <code>cap.grab()</code> just returns <code>false</code>. Any ideas?</p>
  
  <p>Example Code:</p>
  
  <pre><code>import cv2
  
  cv2.namedWindow("preview")
  vc = cv2.VideoCapture(0)
  rval = True
  
  while rval:
      rval, frame = vc.read()
      cv2.imshow("preview", frame)
  
      key = cv2.waitKey(20)
      if key == 27: # exit on ESC
          break
  </code></pre>
  
  <ul>
  <li>Mac OS 10.8.5</li>
  <li>Python 2.7.5 (but also not working from inside a C++ app)</li>
  <li>OpenCV 2.4.6.1</li>
  </ul>