February 23, 2026
Barcode bops, cardboard ops
QRTape – Audio Playback from Paper Tape with Computer Vision (2021)
Paper Tape Music? Internet Split Between Retro Genius and Reinventing the Reel
TLDR: QRTape plays audio from a printed paper strip of QR codes using a webcam and software magic. Comments split between calling it old cinema tech (sound-on-film/Dolby), artsy demands for spectrogram glitchiness, and nerds pushing Data Matrix—showing retro DIY storage can spark big debates over practicality versus playful creativity.
Someone just built a cardboard “tape deck” that plays music from a long strip of paper covered in QR codes—yes, the little square barcodes—read by a webcam. The audio comes out thanks to clever software compression and computer vision. It’s called QRTape, and the internet immediately split into camps.
On one side, the history buffs cried, “This is basically sound-on-film!” Others piled on with “Dolby did this on movie reels,” complete with tiny barcode-like marks between sprocket holes. The arts crowd pushed back: ditch QR, print a spectrogram (a picture of sound) and embrace the glitches—make the tape an instrument, not just a storage format. One shared a trippy video.
Meanwhile, the practical nerd squad nitpicked the code choice: swap QR for Data Matrix (another barcode that packs more into less space) for smoother scanning. And the jokesters? They begged for an app to wave your phone over a vinyl record and auto-play, and dubbed it the ultimate “mixtape you can print at Staples.”
The vibe: delightfully chaotic. Some see a quirky retro flex; others see a clever remix of old cinema tech. And everyone agrees the cardboard, rubber-band, Arduino setup is peak maker energy—equal parts genius and garage band.
Key Points
- •QRTape encodes audio as sequential QR codes on a continuous paper tape.
- •A webcam reads the codes while a stepper motor and Arduino advance the tape at a constant speed.
- •The hardware is built from simple materials: cardboard, paper towel core spools, and a rubber-band belt.
- •Software uses the ZBar library for barcode decoding and the Opus codec for audio compression.
- •Potential improvements include tape centering, dual-motor transport for rewinding, and closed-loop control for error correction.