old_contents: from cam import OpenCV_Cam
  import cv2
  
  cam = OpenCV_Cam(0)
  cam.size = (1920, 1080)
  
  KEY_ESC = 27
  KEY_SPACE = ord(' ')
  prevFrame = None
  i = 0 
  
  fourcc = cv2.cv.CV_FOURCC(*'XVID')
  video = cv2.VideoWriter('output.avi',fourcc, 3.0, (1920,1080), isColor =True)
  
  
  while True:
      # Capture frame-by-frame
      frame = cam.read()
  	
      # image processing functions
      
      # Load the frame into a window named as 'Press any key to exit'
  
      if (prevFrame is not None):
          showFrame = cv2.addWeighted(frame,0.7,prevFrame,0.3,0)
      else:
          showFrame = frame
      
      resizeShowFrame = cv2.resize(showFrame, (0,0), fx = 0.5, fy = 0.5 )
      cv2.imshow('Press ESC to exit', resizeShowFrame)
      
      # wait for the key
      key_code = cv2.waitKey(10)
  	
      if key_code is KEY_SPACE:
          cv2.imwrite('frame'+str(i)+'.png', frame)
          video.write(frame)
          prevFrame = frame
          i += 1
      elif key_code is KEY_ESC:
          break
  cv2.destroyAllWindows()	
  cam.release()
  video.release()
  
new_contents: from cam import OpenCV_Cam
  import cv2
  import os.path
  
  
  cam = OpenCV_Cam(0)
  cam.size = (1920, 1080)
  
  KEY_ESC = 27
  KEY_SPACE = ord(' ')
  prevFrame = None
  i = 0 
  
  fname="frame.png"
  if os.path.isfile(fname):
      prevFrame = cv2.imread(fname)
  
  
  fourcc = cv2.cv.CV_FOURCC(*'XVID')
  video = cv2.VideoWriter('output.avi',fourcc, 3.0, cam.size, isColor =True)
  
  
  while True:
      # Capture frame-by-frame
      frame = cam.read()
  	
      # image processing functions
      
      # Load the frame into a window named as 'Press any key to exit'
  
      if (prevFrame is not None):
          showFrame = cv2.addWeighted(frame,0.7,prevFrame,0.3,0)
      else:
          showFrame = frame
      
      resizeShowFrame = cv2.resize(showFrame, (0,0), fx = 0.5, fy = 0.5 )
      cv2.imshow('Press ESC to exit', resizeShowFrame)
      
      # wait for the key
      key_code = cv2.waitKey(10)
      
      if key_code is KEY_SPACE or key_code == 2228224:
          cv2.imwrite('frame'+str(i)+'.png', frame)
          video.write(frame)
          prevFrame = frame
          i += 1
      elif key_code is KEY_ESC:
          break
  cv2.destroyAllWindows()	
  cam.release()
  video.release()
  
subject: Add support for presenter and continuing frame capture