I think that you are posting in the wrong forum: How is this a Python question? Ignoring that issue, you are confused again: A "music file" doesn't "play all the way through" because it holds music, but does not play it. In general terms: To have something happen after something else, you create a supervisor program that tells the system what to do in what order, and you run that program.
griswolf
Veteran Poster
1,165 posts since Apr 2010
Reputation Points: 344
Solved Threads: 256
No need for subprocesses to run things in sequence:
import os
os.sytem('music_player loud_music.mp3') # silly example
os.system('video_player spinning_things.mp4') # more silliness
# etc
griswolf
Veteran Poster
1,165 posts since Apr 2010
Reputation Points: 344
Solved Threads: 256