A simple idiom to gather bitmaps and make a movie using python and ffmpeg

mkanim.py

#!/usr/bin/env python

import os
import glob
import shutil
import subprocess

#ffmepg parameters
# file sequence format
dstform = u'a{seq:08d}.png' # python style
dstform_c = u'a%08d.png' # C and ffmpeg style

# base frame rate per picture (frames)
frpp = 5 

# video framerate (fps)
vfr = 25
# video bandwidth
vbw = '2000k'
# output video
output = u'video.mp4'

def src_yield():
    # source
    srces = sorted(glob.glob('../p????????.png'))
    first = srces[0]
    last = srces[-1]

    leading_count = 5
    # prologue
    for i in range(leading_count):
        yield first

    for i in srces:
        yield i

    # epilogue
    for i in range(leading_count):
        yield last

for i, s in enumerate(src_yield(), 1):
    d = dstform.format(seq=i)
    print(s, '->', d)
    shutil.copy(s, d)

# ffmpeg command line
cmdline = ['ffmpeg',
        '-r', '{frpp:d}'.format(frpp=frpp),
        '-i', '{dstform_c:s}'.format(dstform_c=dstform_c),
        '-b:v', '{vbw:s}'.format(vbw=vbw),
        '-r', '{vfr:d}'.format(vfr=vfr),
        '-vf', '"scale=trunc(iw/2)*2:trunc(ih/2)*2"', # if pix is odd, trancate it (http://stackoverflow.com/questions/20847674/ffmpeg-libx264-height-not-divisible-by-2)
        '-pix_fmt', 'yuv420p', # for compatibility to windows media player; discussion in http://ffmpeg.org/pipermail/ffmpeg-user/2014-March/020455.html
        '{output:s}'.format(output=output)]

try:
    retcode = subprocess.call(cmdline)
    if retcode < 0:
        print('process is aborted by signal', -retcode)
    else:
        print('process is normaly terminated', retcode)
except OSError as e:
    print('os error', e)