[OTHER] libcap development headers required for python-prctl

Running the installation commands in the README yields an error when attempting to install the python-prctl dependency:

Collecting python-prctl
  Using cached python-prctl-1.8.1.tar.gz (28 kB)
  Preparing metadata (setup.py) ... error
  error: subprocess-exited-with-error
  
  × python setup.py egg_info did not run successfully.
  │ exit code: 1
  ╰─> [1 lines of output]
      You need to install libcap development headers to build this module
      [end of output]
  
  note: This error originates from a subprocess, and is likely not a problem with pip.
error: metadata-generation-failed

× Encountered error while generating package metadata.
╰─> See above for output.

This can be solved by installing the libcap development headers. It might be worth including this in the README installation instructions, changing this:

sudo apt install -y python3-libcamera python3-kms++

to:

sudo apt install -y python3-libcamera python3-kms++ libcap-dev

[davidplowman]

The Lite version of the OS doesn’t include Qt or OpenGL, so it’s still quite small (and those features of Picamera2 won’t work unless you fetch those dependencies explicitly).

I would also caution a bit about updating Picamera2 on the fly. libcamera doesn’t have a stable API yet so it’s very easy for libcamera and Picamera2 to get out of sync. In fact we’ve just been through another bout of this (bugs to do with “Jpeg” and “Sycc”) and it’s just pain all round. If you can stick to sudo apt upgrade then you’ll always get packages that work together.

[davidplowman]

Or is it related to the fact that you were installing prctl with pip? I generally have more trouble with pip because stuff tends not to be available pre-compiled which causes all sorts of headaches. Does installing from apt work correctly for you? This is normally what I would recommend.