sorting a video on brightness

using FFMPEG to make images from video file
using Python PIL to convert every image to a 1x1 pixel image, and give it a brightness value
sorting the output images by brightness value
copying and renaming the images with SHUTIL
using FFMPEG to make a video from the images

inputFilename: input video
outputFilename: output images (frames)
exportFilename: export video

from PIL import Image
import os, shutil
from glob import glob

# ***FROM VIDEO TO IMAGE***
cmd = "ffmpeg -i inputFilename.mpeg -f image2 -r 1 -an -y outputFolder/outputFilename%04d.jpg"
print cmd 
os.system(cmd)

# ***SORTING IMAGES ON BRIGHTNESS (make grayscale, convert to 1x1px image, value the grayscaleness of this pixel) ***
def avg(p):
	pil_im = Image.open(p)
 
	i=pil_im.convert('L')
	i.thumbnail((1,1))
	g=i.getpixel((0,0))
	return g
 
imgs = glob("outputFolder/*.jpg")    
imgs.sort()
 
d = []
for x in imgs:
	d.append((avg(x), x))
d.sort()
print d

os.system(mkdir -p sorted)

i=0
for g, image in d:
	newname='sorted/sorted{0:04d}.jpg'.format(i)
	print "copying", image , "to", newname
	shutil.copyfile(image, newname)
	i=i+1

# ***FROM IMAGES TO VIDEO***
cmd = "ffmpeg -f image2 -r 24 -i sorted/sorted%04d.jpg -y exportFilename.mp4"
print cmd
os.system(cmd)