timelapse.py

from PIL import Image
import os, sys, cv2, numpy

path = sys.argv[1]
filename = sys.argv[2]
blendCount = int(sys.argv[3])

files = os.listdir(path)
files = sorted(files)

previousImage = Image.open(path + '/' + files[0])
height, width, layers = numpy.array(previousImage).shape

video = cv2.VideoWriter(filename, -1, 30, (width, height))

for imageFilename in files:
    image = Image.open(path + '/' + imageFilename)
    if files[0] != imageFilename:
        for i in range(1, blendCount + 1):
            print 'Blending ' + str(i / float(blendCount + 1))
            blendedImage = Image.blend(previousImage, image, i / float(blendCount + 1))
            video.write(cv2.cvtColor(numpy.array(blendedImage), cv2.COLOR_RGB2BGR))

    print 'Adding ' + imageFilename
    video.write(cv2.cvtColor(numpy.array(image), cv2.COLOR_RGB2BGR))

    previousImage = image

video.release()

print width
print height

Usage: timelapse.py ~/Downloads/directory-with-photos-only destination-file.mp4 1