python How can I stop an infinite while loop and continue with rest of code?

Question

The problem is that I can not exit the while loop without stopping the entire program.

When I execute the code on my Raspberry Pi, the camera starts recording, but when I want to end the video and press Ctrl+c, the entire program stops instead of continuing after the while loop. I thought the signal handler would catch the keyboard interrupt but it does not.

My code:

import picamera
import signal
from time import sleep
from subprocess import call

def signal_handler(signal, frame):
        global interrupted
        interrupted = True

signal.signal(signal.SIGINT, signal_handler)

interrupted = False

# Setup the camera
with picamera.PiCamera() as camera:
    camera.resolution = (1640, 922)
    camera.framerate = 30

    # Start recording
    camera.start_recording("pythonVideo.h264")

while True:
        sleep(0.5)
        print("still recording")

        if interrupted:
                print("Ctrl+C pressed")
                camera.stop_recording()
                break

# Stop recording
#camera.stop_recording()

# The camera is now closed.

print("We are going to convert the video.")
# Define the command we want to execute.
command = "MP4Box -add pythonVideo.h264 convertedVideo.mp4 -fps 30"
#Execute command.
call([command], shell=True)
# Video converted.
print("Video converted.")

What I tried:

bflag = True
while bflag ==True:
        sleep(0.5)
        print("still recording")

        if interrupted:
                print("Ctrl+C pressed")
                camera.stop_recording()
                bflag = False

Error:

pi@raspberrypi:~/Documents/useThisFolder $ python cookieVideo.py 
still recording
still recording
still recording
still recording
still recording
^Cstill recording
Ctrl+C pressed
Traceback (most recent call last):
  File "cookieVideo.py", line 29, in <module>
    camera.stop_recording()
  File "/usr/lib/python2.7/dist-packages/picamera/camera.py", line 1193, in stop_recording
'port %d' % splitter_port)
picamera.exc.PiCameraNotRecording: There is no recording in progress on port 1

replace the "while True" with while somevar, and change this variable to False when you want to exit the loop — Tamar
– Tamar, Commented Jun 14, 2017 at 20:38
There is no need for things like "Disclaimer: Absolute noob attempting to explain a question.". The onus of asking a proper question is on you regardless of status, and trust me when I say noobishness will show if it's there. No need to apologize for it, just take the time to listen and learn. — Mad Physicist
– Mad Physicist, Commented Jun 14, 2017 at 20:40

mdurant · Accepted Answer · 2017-06-14 20:40:07Z

4

This would do it:

while True:
    try:
        sleep(0.5)
        print("still recording")
    except KeyboardInterrupt:
        print("Ctrl+C pressed")
        camera.stop_recording()
        break

answered Jun 14, 2017 at 20:40

mdurant

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6 Comments

Pytrik Over a year ago

Thank you. However, when I implement your solution, ctrl+c does nothing. The while loop keeps going.

mdurant Over a year ago

You need this code instead of the signal handler stuff.

Pytrik Over a year ago

If I use this code instead, I get the error mentioned in the problem description.

mdurant Over a year ago

Ah, this needs to be within the with picamera.PiCamera() as camera block. I suspect recording stops automatically when you leave that block.

Pytrik Over a year ago

It is fixed. It was an indentation problem. I needed to use 4 spaces instead of tabs, because I am modifying the code using nano (I think that is the reason, don't know for sure). Thank you.

|

Vape Waves · Accepted Answer · 2017-06-14 21:51:05Z

-1

As you can see it works perfectly with @mdurant's code.

edited Jun 14, 2017 at 21:51

answered Jun 14, 2017 at 20:49

Vape Waves

13 bronze badges

2 Comments

Pytrik Over a year ago

When I try this it gives an error, which I added to the question description.

Vape Waves Over a year ago

The code provided by @mdurant works perfectly for me, try it again and see that your indentation is correct.

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