No barcode scanning on Samsung Galaxy Tab2 - Android 4.4.2

[mayuricmarix]

No Barcode scanning on: Galaxy Tab 2 - (but working on MI and Moto)

On some phones (e.g. Galaxy Tab 2), it didn't detect barcode .

[alexzaitsev]

Affirmative. Doesn't detect on 4.1.2 devices: Samsung Galaxy Young Duos GT-S6312 - 2023, Samsung S3 Mini (GT-I8190) - 2088, Sony XPERIA P - 2015 as well. Vision versions tested: 9.2.0, 9.4.0

[pchx-zz]

Does adb logcat return anything interesting when you attempt to use the Barcode API?

Specifically, any messages with the "Vision" tag, like: Vision: Supported ABIS: [...]

[alexzaitsev]

@pchx As side effect the preview is slightly stretched on these devices. I investigated how it works on these devices and I discovered that it actually scans but not all QR codes.

I have 2 QR codes. This one is original QR code . And this is the same but generated with [http://www.qr-code-generator.com/](this generator) (Text -> "EAAAAAZGXSV98XJMOijICTUjAg5%2FfPwYnrgtQ%2BrBtO%2Ba9M9TCdDD8GQ38cFaxZyVOdXSxw%3D%3D||ST1477" without quotes). .

Both of them are successfully recognized on Nexus 5 and other high end devices. format: 256 displayValue:EAAAAAZGXSV98XJMOijICTUjAg5%2FfPwYnrgtQ%2BrBtO%2Ba9M9TCdDD8GQ38cFaxZyVOdXSxw%3D%3D||ST1477

But on the devices listed above it doesn't recognize the original qrcode but recognizes the generated one. I see that they differ however I cannot instantiate what's the difference because Nexus 5 shows that they have the same format (256).

Also I logged this method to be sure that it's called.

@Override
            public void receiveDetections(Detector.Detections<Barcode> detections) {
                final SparseArray<Barcode> barcodes = detections.getDetectedItems();
                Log.d("qrcode", "detector is operational: " + detections.detectorIsOperational());
                Log.d("qrcode", "metadata: " + (detections.getFrameMetadata() == null ? "null" :
                        (detections.getFrameMetadata().getId() +  " " + detections.getFrameMetadata().getFormat()+
                        " " + detections.getFrameMetadata().getWidth() +
                        "x" + detections.getFrameMetadata().getHeight())));
                if (barcodes.size() != 0) {
                    Log.d("qrcode", "barcodes size: " + barcodes.size());

I'm able to see the logs on the devices where the original qr code cannot be scanned:

11-01 10:48:50.121 12702-13233/com.talk D/qrcode: detector is operational: true
11-01 10:48:50.121 12702-13233/com.talk D/qrcode: metadata: 263 -1 240x320

however barcodes.size() is 0.

And if I scan generated one:

11-01 11:23:31.159 28282-31184/com.talk D/qrcode: detector is operational: true
11-01 11:23:31.159 28282-31184/com.talk D/qrcode: metadata: 394 -1 720x960
11-01 11:23:31.159 28282-31184/com.talk D/qrcode: barcodes size: 1
11-01 11:23:31.710 28282-28282/com.talk D/qrcode: format: 256 value:EAAAAAZGXSV98XJMOijICTUjAg5%2FfPwYnrgtQ%2BrBtO%2Ba9M9TCdDD8GQ38cFaxZyVOdXSxw%3D%3D||ST1477

It's definitely the library problem because the same code recognized correctly on the Nexus 5. Please give me some advice what to do. Also please note the existing of the stretch effect.

[pchx-zz]

The preview frames returned by the Nexus 5 are 720x960 (691200 px^2) while the other device you tested on only returns 240x320 (76800 px^2). In other words, the Nexus 5 gives us 9x the number of pixels -- this doesn't make a difference on a clean image (such as the version you generated), but it does when the QR code is printed on a small receipt.

Basically, the Barcode API requires a higher resolution image to properly read QR codes that are of low quality or are damaged.

[alexzaitsev]

@pchx in this way we should have some error callback which is called in such situation. It's better to show at least error message to user than not to react for his actions at all. If it's possibly to detect such situation of course. Thank you for explanation.

[pchx-zz]

In this case, the QR code probably wasn't detected at all. It's very unlikely that an error callback would provide any useful information in such a situation.

[alexzaitsev]

Yes, it's an actual behavior. But it's confusing. On high-end devices it recognises QR code as expected but on low-end ones it doesn't work. I see that it's really hard to do anything with this.