Python Bindings on Bullseye

[fiepfiep]

Steps to reproduce:

start from raspberry pi os Bullseye (lite) 64 bit.

python3 
import libcamera

works fine now

then, remove libcamera from apt, because we want to build our own:

sudo apt remove libcamera0

install libcamera according to:
rpi documentation

python3
>>> import libcamera
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
ModuleNotFoundError: No module named 'libcamera'

errors out.

why does this happen...:

...
installing symlink pointing to libcamera-base.so.0.5.2 to /usr/local/lib/aarch64-linux-gnu/libcamera-base.so.0.5
Installing symlink pointing to libcamera-base.so.0.5 to /usr/local/lib/aarch64-linux-gnu/libcamera-base.so
Installing symlink pointing to libpisp.so.1.2.1 to /usr/local/lib/aarch64-linux-gnu/libpisp.so.1
Installing symlink pointing to libpisp.so.1 to /usr/local/lib/aarch64-linux-gnu/libpisp.so
Installing symlink pointing to libcamera.so.0.5.2 to /usr/local/lib/aarch64-linux-gnu/libcamera.so.0.5
Installing symlink pointing to libcamera.so.0.5 to /usr/local/lib/aarch64-linux-gnu/libcamera.so
Running custom install script '/home/pi/libcamera/src/ipa/ipa-sign-install.sh /home/pi/libcamera/build/src/ipa-priv-key.pem lib/aarch64-linux-gnu/libcamera/ipa/ipa_rpi_vc4.so lib/aarch64-linux-gnu/libcamera/ipa/ipa_rpi_pisp.so'

libcamera shared objects are in : /usr/local/lib/aarch64-linux-gnu but this is not in python path.
libcamera package is in: /usr/local/lib/python3/dist-packages/libcamera/

where does python look for packages?

>>> import sys
>>> sys.path
['', '/usr/lib/python39.zip', '/usr/lib/python3.9', '/usr/lib/python3.9/lib-dynload', '/usr/local/lib/python3.9/dist-packages', '/usr/lib/python3/dist-packages', '/usr/lib/python3.9/dist-packages']

the libcamera location is not there.

how to solve this? Add another folder to the python path:
export PYTHONPATH=/usr/local/lib/python3/dist-packages:$PYTHONPATH

now libcamera import works.

why is the current behavior like this? why not install to a folder that is part of the python sys path?

[kbingham]

Hi @fiepfiep

Are you on the latest libcamera master branch or a release from raspberry pi?

Recent commits to master not yet in a release touch this area.

For instance

https://git.libcamera.org/libcamera/libcamera.git/commit/?id=d54e5537ca0909339bb6950f3a565c9077406a3c

https://git.libcamera.org/libcamera/libcamera.git/commit/?id=a2b21d60c7bf1d4539da89aaca49b5575e8a4549

And

https://git.libcamera.org/libcamera/libcamera.git/commit/?id=91365356bdcc7aa2525d871c12f35320a805a37a

I'm curious if you got this issue with these commits or without them.

[fiepfiep]

indeed looks like your team is doing some work - but it's not quite ready!!
In any case I've always had to work around this issue, even before these recent commits.

BUT there is a difference.

using an old commit, libcamera binding is installed to:
/usr/local/lib/aarch64-linux-gnu/python3.9/site-packages/libcamera
whilst now it is installed to:
/usr/local/lib/python3/dist-packages/libcamera/

so still wrong, but different.

[naushir]

@davidplowman for visibility.

@fiepfiep yes, we have also noticed this problem with local builds/installations. To be honest, I'm not entirely sure when this behavior changed either. It may be that the upstream libcamera changes will revert this, but I've not tested this yet.

In the interim, there is a workaround where you can set the meson python.platlibdir manually to /usr/local/lib/aarch64-linux-gnu/python3.9/site-packages/libcamera.

[naushir]

I'm going to close this down as there is no active work happening with the above workaround. Shout if you need any more information.