Trouble calling PyDNG from script

This might be a total noob error, but I'm banging my head against the keyboard for some hours now.

Here's what I am trying to do: I have a script "listen.py" that waits for user input via GPIO or UDP command - then takes an image via raspistill(), converts it via PyDNG and uploads it via ftp.

When I launch said listen.py via ssh everything behaves as intended. But when I launch the script via a script that updates listen.py through systemd service I get a ValueError and exit code 1 for PyDNG.

Does anybody have a clue why this is happening?

listen.py:


if  isTakingImage == False:
        isTakingImage = True
        GPIO.remove_event_detect(BUTTON)
        shutter = 1000000 / fractor       #in microseconds / 1s = 1000000us
        timea = datetime.utcnow()
        print("taking image...")

        subprocess.call(['raspistill -o /home/pi/startup/current.jpg --raw -md 3 -awb flash -q 100 -ex spotlight --timeout 2 --nopreview --shutter ' + str(shutter) +' --ISO 100'], shell=True)

        gc.collect()
        time.sleep(1)
        print("extracting dng...")
      #  subprocess.check_call(['python3.7 /home/pi/PyDNG/examples/utility.py current.jpg'], shell=True)

      # use file string input to the jpeg+raw file. 
        d = RPICAM2DNG()
        d.convert('current.jpg')
        timeb = datetime.utcnow()
        print("uploading image")
        from ftplib import FTP

        [ftp stuff]

start.py:

print("updateing scripts")
try:
    ftp = ftplib.FTP("192.168.178.34", "Medusa", "Medusa")
    ftp.login("Medusa", "Medusa")
    lf = open("/home/pi/startup/listen.py", "wb")
    ftp.retrbinary("RETR " + "listen.py", lf.write, 8*1024)
    lf.close()
    lf = open("/home/pi/startup/focus.py", "wb")
    ftp.retrbinary("RETR " + "focus.py", lf.write, 8*1024)
    lf.close()
    ftp.quit()
except ftplib.all_errors as e:
    print('FTP error:', e)

print("done")

print ("starting listen script")

os.system("sudo python3 /home/pi/startup/start.py")`

systemd service start.service:


[Unit]
Description=My Sample Service
Wants=network-online.target
After=network-online.target

[Service]
Type=simple
User=pi
WorkingDirectory=/home/pi
ExecStartPre=/bin/sh -c 'until ping -c1 google.com; do sleep 1; done;'
ExecStart=/usr/bin/python3.7 /home/pi/startup/start.py > /home/pi/start.log 2>&1

[Install]
WantedBy=multi-user.target`

schoolpost / PiDNG

Trouble calling PyDNG from script #36