Ever wondered what that wavy thing under shareable spotify images were? They're scannable codes the scanner is the camera icon in the search bar on mobile. Apparently launched in 2017, but who knows, I never discovered the feature.
Recently they appeared under Start a group session in the connect menu, (the thing you click to play music on another device).
23 bars, I'm guessing bars 1, 12, 23 (first, middle, last) are for calibration, that leaves 20 bars. Each bar has a top and bottom section with 8 states each = 6 bits per bar. Total 120 bit id.
spotify ids are 22 base62 chars, which appears to be a 128bit uuid (128/log2(62)=21.497) or better explained on stack overflow
so where did 8 bits go? idk.