title: python opencv does not find raspberry pi camera
body: <p>ive got this error i dont have any idea why, i search all the internet and could not find solution</p>
  <pre><code>[ WARN:0@0.042] global /io/opencv/modules/videoio/src/cap_v4l.cpp (902) open VIDEOIO(V4L2:/dev/video0): can't open camera by index
  Traceback (most recent call last):
    File &quot;/home/pi/Facial-Recgnition/app/test.py&quot;, line 11, in &lt;module&gt;
      cv2.imwrite(&quot;Image.jpg&quot;, frame)
  cv2.error: OpenCV(4.6.0) /io/opencv/modules/imgcodecs/src/loadsave.cpp:801: error: (-215:Assertion failed) !_img.empty() in function 'imwrite'
  
  
    
  </code></pre>