title: Making a video of cropped frames in Python OpenCV
body: <p>In my program I am reading an original video, then cropping every frame and finally I need to make a video of all the cropped frames.<br>
  The frames are cropped with the size I define (top, bottom, left and right), but it doesn't save it to a video.<br>
  What I'm trying is the following:  </p>
  
  <pre><code>input_video = cv2.VideoCapture(videosPath+"/"+video)
  while True:
      ret, frame = input_video.read()
          if not ret:
              break
      for (top, right, bottom, left) in *****
          crop_img = frame[top:bottom, left:right]
          fourcc = cv2.VideoWriter_fourcc(*'XVID')
          output_movie = cv2.VideoWriter('videoPrueba.avi', fourcc, 30, (450, 360))
          output_movie.write(crop_img)
  </code></pre>
  
  <p>Thanks ! </p>