Packages are built from source on RPi instead of a wheel installation

[asenyaev]

Expected behaviour

Installed OpenCV on Raspberry Pi 4 using a wheel, but not from source.

Actual behaviour

When the opencv-python package is installing on RPi it usually builds from source using opencv-python-4.5.3.56.tar.gz instead of a wheel (e.g. opencv_python-4.5.3.56-cp36-cp36m-manylinux2014_aarch64.whl)

Steps to reproduce

• Example code:

python3 -m pip install --no-cache --force-reinstall opencv-python==4.5.3.56

• operating system: Raspbian GNU/Linux 10 (buster)
• opencv-python version: 4.5.3.56

Issue submission checklist

• [x] This is not a generic OpenCV usage question (looking for help for coding, other usage questions, homework etc.)
• [x] I have read the README of this repository and understand that this repository provides only an automated build toolchain for OpenCV Python packages (there is no actual OpenCV code here)
• [x] The issue is related to the build scripts in this repository, to the pre-built binaries or is a feature request (such as "please enable this additional dependency")
• [x] I'm using the latest version of opencv-python

[abhiTronix]

@asenyaev Raspbian(or Raspberry Pi OS) is available only in a 32-bit version. So opencv_python-4.5.3.56-cp36-cp36m-manylinux2014_aarch64.whl will not work.

However, There is a 64-bit version in development(raspios_arm64 download at https://downloads.raspberrypi.org/), but it's not stable yet or hasn't been updated since 2020.

[theyosh]

I think this is related to https://www.piwheels.org/project/opencv-python-headless/

The builds failed, so no wheel packages for the RPI. Maybe related to #571 ?