I need a method to obtain a video file duration in vlc

Question

I am developing a headless application on a Raspberry Pi Zero 2 W, Bullseye OS, and using VLC (Python) to view video files (h264). I have loaded vlc and python-vlc. I am able to view videos using the play/stop commands, but have to put a timer in between the commands, because I don't know the actual length of the videos.

I have seen get_length() used in a couple of online vlc examples, but I get an error on my system.

    AttributeError: 'MediaListPlayer' object has no attribute 'get_length'

Here is my relevant code:

video_file = '/var/tmp/video.h264'

instance = vlc.Instance("--verbose=0","--no-xlib","--vout=mmal_vout")
media_list = instance.media_list_new([video_file])
list_player = instance.media_list_player_new()
list_player.set_media_list(media_list)

duration = list_player.get_length()            # Without this line, the video plays

list_player.play()
time.sleep(TriggerOnTime.seconds + (TriggerOnTime.microseconds / 1000000) + 1)
list_player.stop()

What am I missing?

I expect to load a time in "duration".