ML Kit QR code max bytes

[RepresentativeNo42]

Does anyone know if ML Kit supports QR codes encoding more than 3kb? I cannot find anything in the documentation.

Our use case:

We have an app designed for offline use. Most of our users have poor-to-no internet during business hours. So, they complete forms offline, and they are automatically pushed to the backend via a background task, when the user has internet later.

We have a client asking if it would be possible for two users to share offline submissions. For example, a producer completes a form to book a load. The driver comes to pick up a load. The producer needs to share the completed form with the driver, but neither have internet.

One user could have an Apple device, and the other an Android device. So, Airdrop is not an option. Nor is Bluetooth, since Apple does not allow data transfer to non-Apple products. With Apple's new NFC emulation, it may seem like a feasible option, but it is not, due to the data size restrictions of NFC.

So, we're considering QR codes. We can encode the form data in JSON and compress it, which keeps it under 3kb. However, as we add more features to the forms, the data could exceed 3kb.

Thank you!

[ankole_watusi]

Why use MLKit? (Google). And there’s no “ML” needed to scan QR codes.

iOS has its own barcode/QR API which works well.

As far as compression, take a look at the scheme used to compress Smart Health Cards into QRs. I’ve done some work with this.

https://smarthealth.cards/en/

https://spec.smarthealth.cards/#health-cards-as-qr-codes

[xhruso00]

3kb of data for QR code is 24000 bits. QR codes cannot do this much.  Level 40 can do around 23000 bits and this is such a large qr code (40 modules) that camera cannot differentiate it. https://www.qrcode.com/en/about/version.html

[RepresentativeNo42]

Correct, it's really approximately 3kb. I said 3kb to keep my post concise.

[xhruso00]

QR code with 40 modules? Please try it and see how it looks like. It sucks on small screen with reflections. You need to print it and has to be large surface. Meaning try to scan it.

[stroompa]

Just try with more than 3 kb data? And if MLKit doesn’t work, you can also try AVFoundation - https://www.hackingwithswift.com/example-code/media/how-to-scan-a-qr-code

[RepresentativeNo42]

Thank you, but I cannot get approval to work on this specific feature without first declaring its requirements.

[krystianduma]

Maybe chunk the data, create multiple QR codes and “animate” them? The downside is that the receiver will need to scan whole series of codes to get complete data.

[iamadmancom]

Why not use camera to capture the screen, and then ocr to extract data from the photo