Segmentation fault while using Raspberry Pi 4 and PiCam

Question

I am working on a project for University, and I am attempting to create a program that takes a picture using the PiCam every 4 seconds or so and then calculates the luminosity of the image.

The programs functions on the first loop, but it breaks during the second loop when it gives a Segmentation Fault

the error is as follows:

mmal: mmal_vc_port_enable: failed to enable port vc.null_sink:in:0(OPQV): ENOSPC
mmal: mmal_port_enable: failed to enable connected port (vc.null_sink:in:0(OPQV))0x15fb150 (ENOSPC)
mmal: mmal_connection_enable: output port couldn't be enabled

Backend terminated or disconnected.Fatal Python error: Segmentation fault

Current thread 0xb6f25ad0 (most recent call first):
File "/usr/lib/python3/dist-packages/picamera/mmalobj.py", line 1331 in _get_framesize
File "/usr/lib/python3/dist-packages/picamera/mmalobj.py", line 1325 in __repr__
File "/usr/lib/python3/dist-packages/thonny/backend.py", line 864 in export_value
File "/usr/lib/python3/dist-packages/thonny/backend.py", line 880 in export_variables
File "/usr/lib/python3/dist-packages/thonny/backend.py", line 927 in _export_stack
File "/usr/lib/python3/dist-packages/thonny/backend.py", line 1027 in _prepare_user_exception
File "/usr/lib/python3/dist-packages/thonny/backend.py", line 1218 in wrapper
File "/usr/lib/python3/dist-packages/thonny/backend.py", line 1259 in execute_source
File "/usr/lib/python3/dist-packages/thonny/backend.py", line 815 in _execute_source
File "/usr/lib/python3/dist-packages/thonny/backend.py", line 801 in _execute_file
File "/usr/lib/python3/dist-packages/thonny/backend.py", line 403 in _cmd_Run
File "/usr/lib/python3/dist-packages/thonny/backend.py", line 204 in handle_command
File "/usr/lib/python3/dist-packages/thonny/backend.py", line 146 in mainloop
File "/usr/lib/python3/dist-packages/thonny/backend_launcher.py", line 87 in <module> Use 'Stop/Restart' to restart.

And this is my code:

import PIL
from PIL import Image
from picamera import PiCamera
from time import sleep

def take_picture():
    #setting the camera
    camera = PiCamera()
    #resolution to (min = 64x64)(max = 2592, 1944)
    camera.resolution = (64, 64)
    #camera take picture
    camera.capture('/home/pi/Desktop/image1.jpg')
#END take_picture
    
def current_average_luma():
    take_picture()
    img = Image.open("/home/pi/Desktop/image1.jpg") #opens image
    
    luma=0 #sum of the luma of each pixels
    pixels = img.width*img.height #number of pixels
    
    for x in range(img.width):
        for y in range(img.height):
            (r, g, b) = img.getpixel((x,y))#get colour touple 
            luma += (0.2126*r + 0.7152*g + 0.0722*b) #calculate luma of RGB data, then add to total
        #END for
    #END for
            
    img.close()#ensure to properly close the image
    return luma/pixels #return average of all pixels
#END average_luma

while (1):
    
    print("the average luma of the image is: ", current_average_luma()) #print light value

    sleep(4)
#END while

I am not sure how to solve this problem, or what is causing it. Any advice is appreciated

Picture of entire error message

Is there any other error message or traceback along with the segfault? — MattDMo, Oct 29 '20 at 20:13
Yes, I added a picture of the entire error message at the end of the question — Miller Timlin, Oct 29 '20 at 20:19
Can you please copy that and paste it as formatted text into the question? Images are not searchable, and can not be interpreted by screen readers for those with visual impairments. See [this post](https://meta.stackoverflow.com/q/285551) for details. Thanks. — MattDMo, Oct 29 '20 at 20:30
I would, but the copy and paste function is not working. I will type it out, but it will take a moment — Miller Timlin, Oct 29 '20 at 20:31
Are you sure that your script is the _only_ thing trying to access the camera? See [this](https://raspberrypi.stackexchange.com/questions/95261/raspberry-pi-camera-failed-to-enable-connection) post. — Random Davis, Oct 29 '20 at 20:36
the only thing i can think of is that it doesnt like the fact that I call it again, so its like creating a new instance of the camera object? — Miller Timlin, Oct 29 '20 at 20:50

score 0 · Answer 1 · answered Oct 29 '20 at 20:53

the code was fixed by doing this:

from PIL import Image
from picamera import PiCamera
from time import sleep
    
def current_average_luma(camera):
    camera.capture('/home/pi/Desktop/image1.jpg')#camera take picture
    img = Image.open("/home/pi/Desktop/image1.jpg") #opens image
    
    luma=0 #sum of the luma of each pixels
    pixels = img.width*img.height #number of pixels
    
    for x in range(img.width):
        for y in range(img.height):
            (r, g, b) = img.getpixel((x,y))#get colour touple 
            luma += (0.2126*r + 0.7152*g + 0.0722*b) #calculate luma of RGB data, then add to total
        #END for
    #END for
            
    img.close()#ensure to properly close the image
    return luma/pixels #return average of all pixels
#END average_luma


#MAIN
camera = PiCamera()#setting the camera
camera.resolution = (64, 64)#set resolution

while (1):   
    print("the average luma of the image is: ", current_average_luma(camera)) #print light value

    sleep(4)
#END while

The issue was that the repeated function call of take_picture() created multiple camera objects, and thus created a conflict.

Segmentation fault while using Raspberry Pi 4 and PiCam

1 Answers1