Create an mp4 from the files in the input directory given. If there aren't a ton, make an animated gif. Assumes ImageMagick (for animated gif) or mjpegtools and ffmpeg for H264-encoded mp4.

pngs_to_video.py

from glob import glob
import sys
from tempfile import NamedTemporaryFile


png_dir = sys.argv[1]
wildcard = os.path.join(png_dir, '*.png')
n = len(glob(wildcard))
if n < 100:
    # for short files, animated gifs are preferable
    subprocess.call("convert -delay 2 -loop 0 %s output.gif" % wildcard).split(" "), cwd=png_dir)
else:
    with NamedTemporaryFile(suffix='.yuv') as f:
        # http://wiki.webmproject.org/howtos/convert-png-frames-to-webm-video
        subprocess.call(("png2yuv -I p -f 24 -b 0 -n %d -j %%06d.png" % n).split(" "), cwd=png_dir, stdout=f)
        subprocess.call(("ffmpeg -i %s -vcodec libx264 -tune animation output_video.mp4" % f.name).split(" "), cwd=png_dir)