[cjbgkagh]

I think many places roll their own. QR codes have a finder pattern of alternating black and white with relative spacing of 1-1-3-1-1 for any line that goes through the center of it. This has a low false positive rate so this step is the most important for performance. Since orientation doesn’t change the pattern horizontal scans are sufficient, once the center, scale, and rotation has been found the rest is fairly straight forward. There isn’t really a good reason why this set up couldn’t be rotation invariant, the processing power required is pretty low.