I've been experimenting with barcodedetector and associated Vision APIs for a week or so and - unfortunately - the conclusion is that they are unreliable. I've tested them with ~10 devices: Samsung and Nexus tablets/phones with Android 4.4 to 6.01.
The common problem was that I could not decode certain QR codes - other apps based on zxing library as well as iPhone had no problems decoding them. The problematic QR codes had one of the following 'flaws': somewhat distorted timing (due to scaling), no quiet zone, or their bitmap data had a bottom/left origin (i.e. image was mirrored).
Also troubling is that the associated APIs (e.g. CameraSource) appear to be buggy. Fortunately, the barcode reader sample comes with open source version so it can be fixed if necessary. The most obvious bug is the way camera resolutions are matched to view sizes without taking into account current orientation. You can clearly see the side effects in the sample - camera preview never fills the containing activity area, especially in the landscape orientation.
Has anyone run into similar problems? Are there any workarounds for the show stoppers - i.e. decoding qr codes?
Thanks.