title: python HIGHGUI ERROR: V4L/V4L2: VIDIOC_S_CROP
body: <p>I'm using python 2.7, Ubuntu 14.04 and cv2. I'm trying to run this simple code:</p>
  
  <pre><code>import cv2
  
  cam = cv2.VideoCapture(0)
  while True:
      ret, frame = cam.read()
      cv2.imshow("webcam", frame)
      cv2.waitKey(1)
  </code></pre>
  
  <p>I want to take a single picture, but instead my webcam stays activated but it only returns this:</p>
  
  <pre><code>HIGHGUI ERROR: V4L/V4L2: VIDIOC_S_CROP
  </code></pre>
  
  <p>What I need to do to fix the problem?</p>