Issue with picamera library - Unable to find libmmal.so

[Minoloi]

Description

I am experiencing an issue with the picamera library on my Raspberry Pi. When running the classify_capture.py script from the google-coral examples, I encounter the following error:

Traceback (most recent call last):
File "/home/admin/coral/pycoral/google-coral/examples-camera/raspicam/classify_capture.py", line 24, in
import picamera
File "/usr/lib/python3/dist-packages/picamera/init.py", line 72, in
from picamera.exc import (
File "/usr/lib/python3/dist-packages/picamera/exc.py", line 41, in
import picamera.mmal as mmal
File "/usr/lib/python3/dist-packages/picamera/mmal.py", line 49, in
_lib = ct.CDLL('libmmal.so')
OSError: libmmal.so: cannot open shared object file: No such file or directory

I have already performed the following steps to address the issue:

Installed the required packages using sudo apt-get install libraspberrypi0 libraspberrypi-dev libraspberrypi-bin.
Verified that the libmmal.so file exists in the /opt/vc/lib/ directory.
Checked the permissions of the libmmal.so file and ensured that it is readable by the executing user.
Upgraded the picamera library using sudo pip3 install --upgrade picamera.
Despite these efforts, the issue persists, and the script is still unable to locate libmmal.so. I would appreciate any guidance or assistance in resolving this problem.

Thank you for your help!

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Issue Type

Bug

Operating System

Linux

Coral Device

USB Accelerator

Other Devices

Rapsberry Pi 4

Programming Language

Python 3.9

Relevant Log Output

Traceback (most recent call last):
  File "/home/admin/coral/pycoral/google-coral/examples-camera/raspicam/classify_capture.py", line 24, in <module>
    import picamera
  File "/usr/lib/python3/dist-packages/picamera/__init__.py", line 72, in <module>
    from picamera.exc import (
  File "/usr/lib/python3/dist-packages/picamera/exc.py", line 41, in <module>
    import picamera.mmal as mmal
  File "/usr/lib/python3/dist-packages/picamera/mmal.py", line 49, in <module>
    _lib = ct.CDLL('libmmal.so')
OSError: libmmal.so: cannot open shared object file: No such file or directory

[Axxoul]

Are you running Bullseye?
Bullseye uses libcamera and therefor the example here is not valid anymore since picamera uses Raspberry Pi's legacy camera stack. picamera2 uses the new libcamera stack. Unfortunately I have not been able to make it work myself. You could try to enable the legacy stack in raspi-config.
Did you find a solution in the meantime?