title: opencv python not enough values to unpack
body: <p>I'm trying to do a gesture controlled smart mirror. But then when I try to run the <code>test.py</code>, the camera was on for one second, and then suddenly closed. This is the output that I got.</p>
  <pre><code>DEBUG:asyncio:Using selector: SelectSelector
  Exception in thread Thread-1:
  Traceback (most recent call last):
    File &quot;C:\Users\admin\AppData\Local\Programs\Python\Python37\lib\threading.py&quot;, line 917, in _bootstrap_inner
      self.run()
    File &quot;C:\Users\admin\AppData\Local\Programs\Python\Python37\lib\threading.py&quot;, line 865, in run
      self._target(*self._args, **self._kwargs)
    File &quot;test.py&quot;, line 85, in ManageMotion
      gesture = motion.GetGesture()
    File &quot;C:\Users\admin\Desktop\SmartMirror\Motion\motion.py&quot;, line 192, in GetGesture
      self.TryToTrackHand()
    File &quot;C:\Users\admin\Desktop\SmartMirror\Motion\motion.py&quot;, line 116, in TryToTrackHand
      foundPalm = search_hand.SearchPalmFromMask(search_hand_mask)
    File &quot;C:\Users\admin\Desktop\SmartMirror\Motion\gesture.py&quot;, line 134, in SearchPalmFromMask
      if self.InitFromMask(search_hand_mask):
    File &quot;C:\Users\admin\Desktop\SmartMirror\Motion\gesture.py&quot;, line 101, in InitFromMask
      (_, contours, _) = cv2.findContours(search_hand_mask, cv2.RETR_TREE, cv2.CHAIN_APPROX_SIMPLE)
  ValueError: not enough values to unpack (expected 3, got 2)
  
  [ WARN:0] global D:\Build\OpenCV\opencv-4.1.2\modules\videoio\src\cap_msmf.cpp (674) SourceReaderCB::~SourceReaderCB terminating async callback
  </code></pre>