Very simple Python program to control the picam-stream script. Helpful for scripting the livestream. See https://gist.github.com/russfeld/0878b1f8eaf7409136b9125ce5e1458f

picam-stream-control.py

import subprocess
import time
import os
import signal

# Some trigger condition to start stream
process = subprocess.Popen("/home/pi/picam-stream.sh", preexec_fn=os.setsid, shell=True)

# Wait for some condition to stop stream
time.sleep(15)

# Stop Stream
os.killpg(os.getpgid(process.pid), signal.SIGTERM)

print("Done")