ZBar is an open source software suite for reading bar codes from various sources, including webcams. As its development stopped in 2012, I took the task of keeping it updated with the V4L2 API. This is the main repository for it. There's a clone at at LinuxTV.org, and another one at gitlab.
Would be cool to have support for that in
zbar
! See https://jabcode.org/ and the reference implementation https://github.com/jabcode/jabcode.