import subprocess

import re

def get_length(filename):

    result = subprocess.Popen(["ffprobe", filename],

                                stdout=subprocess.PIPE,

                                stderr=subprocess.STDOUT)

    for x in result.stdout.readlines():

        if b"Duration" in x:

            print(x)

            x = re.search(rb"Duration.+?\d{2}:(\d{2}):\d{2}", x)

            return int(x.group(1))

print(get_length(r"C:\Users\Administrator\Desktop\1.mp4"))

'''

b'  Duration: 00:17:25.00, start: 0.000000, bitrate: 507 kb/s\r\n'

17

'''