Python script to monitor when a webcamera is activated on Linux

camera-on-air.py

import shutil
import subprocess
import time

COMMANDS = [shutil.which("lsmod")]
MOD_NAME = b"uvcvideo"


def get_uvc_user_count() -> int:
    """
    Obtain the number of users of the UVC Video module
    """
    result = subprocess.check_output(COMMANDS)
    for line in result.splitlines():
        cols = line.split()
        if cols[0] == MOD_NAME:
            return int(cols[2])


def on_air():
    """
    Camera is in use
    """
    print("On Air!")


def off_air():
    """
    Camera is no longer in user
    """
    print("Off Air!")


def monitor_camera(check_frequency: float = 1):
    """
    Monitor state of camera
    """
    is_active = False

    while True:
        user_count = get_uvc_user_count()
        if user_count > 0:
            if not is_active:
                is_active = True
                on_air()
        else:
            if is_active:
                is_active = False
                off_air()

        time.sleep(check_frequency)


def main():
    monitor_camera()


if __name__ == '__main__':
    main()