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'))

def frames_to_timecode(frames):
    return '{0:02d}:{1:02d}:{2:02d}:{3:02d}'.format(frames / (3600 *
        framerate), frames / (60 * framerate) % 60, frames / framerate % 60,
        frames % framerate)
How to do timecode calculation?