Python script to countdown to a specified datetime and write to a file. I use this for OBS countdown timers.

countdown.py

from time import sleep
from datetime import datetime, time

def date_diff(date1, date2):
  timedelta = date2 - date1
  return timedelta.days * 24 * 3600 + timedelta.seconds

def min_sec(seconds):
    minutes, seconds = divmod(seconds, 60)
    return minutes, seconds

leaving_date = datetime.strptime('2020-12-05 12:00:23', '%Y-%m-%d %H:%M:%S')
now = datetime.now()
diff = date_diff(now, leaving_date)
old_min = 0
old_sec = 0

while diff > 0:
    min, sec = min_sec(date_diff(now, leaving_date))

    if old_min != min or old_sec != sec:
        print("{:02d}:{:02d}".format(min, sec))

    old_min = min
    old_sec = sec
    now = datetime.now()
    diff = date_diff(now, leaving_date)
    sleep(0.2)

    with open('countdown.txt', 'w') as file:
        file.write("{:02d}:{:02d}".format(min, sec))