new_contents: from skvideo.io import VideoCapture
  from skvideo.metrics import ssim, psnr, vifp
  import sys
  import json
  
  filename1, filename2 = sys.argv[1], sys.argv[2]
  
  cap1 = VideoCapture(filename1)
  cap1.open()
  print str(cap1.get_info())
  
  cap2 = VideoCapture(filename2)
  cap2.open()
  print str(cap2.get_info())
  
  def rgb_to_y(img):
      return 0.299 * img[:,:,0] + 0.587 * img[:,:,1] + 0.114 * img[:,:,2]
  
  frame_num = 0
  while True:
      retval1, image1 = cap1.read()
      retval2, image2 = cap2.read()
  
      if not retval1 and not retval2:
          break
      elif not retval1 or not retval2:
          print "error: input files have different number of frames"
          break
  
      if image1.shape != image2.shape:
          print "error: input files have different resolutions"
  
      y_image1 = rgb_to_y(image1)
      y_image2 = rgb_to_y(image2)
  
      psnr_metric = psnr.psnr(image1, image2)
      ssim_metric = ssim.ssim(y_image1 / 255.0, y_image2 / 255.0)
      vifp_metric = vifp.vifp_mscale(y_image1, y_image2)
  
      print json.dumps({ "frame_num":frame_num, "psnr":psnr_metric, "ssim":ssim_metric, "vifp":vifp_metric })
      frame_num += 1
  
  cap1.release()
  cap2.release()
  print "done"
  
subject: Add example that compares two files with every metric