qr code animations

Abstract

I did a proof of concept for scanning animated qrs automatically (without buttons): https://github.com/gorazdko/specter-diy/tree/animiated_qr_video

• scanner is scanning in continuous mode with the following parameters:

# 100ms
INTERVAL_OF_SCANNING = 0x01
# 0x32 - enable 5 second delay
DELAY_OF_SAME_BARCODES = 128 + 0x32

Animations can be played with https://github.com/gorazdko/specter-desktop/tree/qr_animation

• def qr_animate(qrtext, max_len=100): max_len determines the maximum chunk size of the frame
• interval of animating can be set in window.setInterval(function(){full_psbt.qra_next()}, 250)
• qrs are set for high recovery level (30%): QRCode.CorrectLevel.H

Results

Its feasible, though results arent nearly as good as in https://divan.dev/posts/animatedqr/ where

The best result was 1.4 secs, which is almost 9KB/s! This result has been recorded at a rate of 11 frames per second and chunk size of 850 bytes with Medium recovery level

Here, one setting that works ok is 250 ms interval with 100 byte frames. For optimal settings one should play with parameters

Should we prefer this method over the one with buttons?

[stepansnigirev]

I think we should use animated QR codes only when it is super necessary - rare transactions with many inputs and outputs, very large multisig wallets.

With current PSBT optimizations even a large multisig fits in one QR codes if there are not too many inputs and outputs. And if people want to make a huge transaction, they should be ready to hold their wallet still for quite some time )))

Let’s make it into a pull request. For specter-desktop I suggest to add a checkbox or button animate QR code. So normally QR code is large and shows full data, but if you check the checkbox it becomes smaller and animated.

The same for signed psbt QR code in specter-diy - we have enough space to add a checkbox that would animate the QR code. By default let’s keep it static.

[gorazdko]

I tried it out, specter-desktop part works great

the qrcode library is not ok. it has a bug: https://github.com/davidshimjs/qrcodejs/issues/220

You will notice it when changing max_len when having QRCode.CorrectLevel.H

I need to look into your code and understand the logic

i will write a couple of sentences later about how this works, the limitations and other things i noticed…