def timecode_to_frames(timecode):
    return sum(f * int(t) for f, t in zip((3600 * framerate, 60 * framerate,
        framerate, 1), timecode.split(':')))
print(timecode_to_frames('15:41:08:02') - timecode_to_frames('15:41:07:00'))
How to do timecode calculation?