Play different videos with omxplayer depending on reported sonar distance

Question

I am a new to Python.

What I want to do is that playing different videos depends on distance using Ultrasonic sensor.

For example,

if the distance <= 20, play movie1.

if the distance > 20, play movie2.

It works, and that seems quite simple.

But I have a problem. The video is not changed instantly. After playing it completely, it responds again.

So even though the distance is <20, the movie1 is still going. After finishing it, movie2 appears.

I want to change the video as soon as the distance is changed, not waiting until the video is finished. Maybe I need some code to kill OMXPlayer? I have no idea.

Below is my code.

#Libraries
import RPi.GPIO as GPIO
import time, sys, os
from subprocess import Popen
import subprocess as sp

distance = 400
zone = 1  
# to know if omxplayer is playing (= None) or not


#GPIO Mode (BOARD / BCM)
GPIO.setwarnings(False)
GPIO.setmode(GPIO.BCM)

#set GPIO Pins
GPIO_TRIGGER = 18
GPIO_ECHO = 24

#set GPIO direction (IN / OUT)
GPIO.setup(GPIO_TRIGGER, GPIO.OUT)
GPIO.setup(GPIO_ECHO, GPIO.IN)

# Videos definitions
movie1 = ('/home/pi/Videos/test1.mp4')
movie2 = ('/home/pi/Videos/test2.mp4')

def distance():
    # set Trigger to HIGH
    GPIO.output(GPIO_TRIGGER, True)

    # set Trigger after 0.01ms to LOW
    time.sleep(0.00001)
    GPIO.output(GPIO_TRIGGER, False)

    StartTime = time.time()
    StopTime = time.time()

    # save StartTime
    while GPIO.input(GPIO_ECHO) == 0:
        StartTime = time.time()

    # save time of arrival
    while GPIO.input(GPIO_ECHO) == 1:
        StopTime = time.time()

    # time difference between start and arrival
    TimeElapsed = StopTime - StartTime
    # multiply with the sonic speed (34300 cm/s)
    # and divide by 2, because there and back
    distance = (TimeElapsed * 34300) / 2

    return distance

if __name__ == '__main__':
    try:
        while True:
            dist = distance()
            print ("Measured Distance = %.1f cm" % dist)
            time.sleep(1)

            if (distance() <= 20):
                zone = 1
            elif (distance() > 20):
                zone = 2
            if (zone == 1):
                Popen(['omxplayer', '-b', movie1])
            if (zone == 2):
                Popen(['omxplayer', '-b', movie2])

    except KeyboardInterrupt:
    # exits when you press CTRL+C
      os.system('killall omxplayer.bin')
      GPIO.cleanup()    

Answer 1

There is no need for blood ;) - when the distance changes, before

Popen(['omxplayer', '-b', movie2])

issue a command to stop the currently playing video

Answer 2

Type the command,

$ ps -A | grep omxplayer 

Into a terminal session while the video is running. It should give you the number of the process that you can kill.

Using the command...

$ kill [processnumber]

Then you can use those same shell commands as sub processes in your Python code once you get it to work on a terminal session.