I built a QR code with my bare hands to see how it works

I built a QR code with my bare hands to see how it works

by Veritasium

Formal & Physical Sciences Computing & Cybersecurity UComputing and Information TechnologyUYComputer science
🎙 Veritasium 👥 21.1M 📅 September 30, 2024 ⏱ 35 min 👁 9.6M 📄 science communication 🧭 2026-08-27
Available in: English (current) Français

Keywords

QR codeerror correctionReed-SolomonMorse codebarcode

Summary

In this video, Veritasium’s Derek Muller explores the history and inner workings of QR codes, from their conceptual origins in Morse code to their modern ubiquity. He begins with the story of Samuel Morse, whose personal tragedy motivated him to develop the electric telegraph, and then traces the evolution of barcodes, from the linear UPC to the 2D matrix codes that preceded QR codes. The core of the video is a hands-on demonstration: Muller builds a QR code on a Go board, explaining how data is encoded in binary, how the code is structured with position and alignment patterns, and how error correction works. He introduces the concept of Hamming distance and Reed-Solomon error correction, showing how redundant data allows QR codes to be read even when damaged. The video also covers the history of QR codes’ development by Masahiro Hara at DENSO, their open patent policy, and their rise to global popularity with smartphones and the COVID-19 pandemic. Finally, it touches on security concerns and the future of QR codes.

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Critical Evaluation

Value of the Information & Strength of the Argument

The video provides a comprehensive and engaging explanation of QR code technology, combining historical narrative with technical detail. The argumentation is solid, building from basic concepts to more complex ideas like error correction. The use of a physical Go board to construct a QR code is an effective pedagogical tool, making abstract concepts tangible. The explanation of Reed-Solomon codes is particularly clear, using a simple polynomial example to illustrate the principle before discussing its real-world applications. The video also benefits from interviews with Masahiro Hara, the inventor of QR codes, adding authenticity and depth.

Scientific Rigor, Source Quality, Title Accuracy

The video demonstrates high scientific rigor, with references to primary sources and historical documents. The explanation of error correction is technically accurate, and the video correctly attributes the development of QR codes to Masahiro Hara and DENSO. The title accurately reflects the content, as the video indeed shows the process of building a QR code. The video also includes a brief sponsored segment, which is clearly disclosed. The description provides a comprehensive list of references, including links to images and videos used, as well as a dedicated references page.

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Title / Content Match

The title accurately reflects the video's content, as Derek Muller physically builds a QR code and explains its inner workings.

Quality & Reliability

9/10

High-quality explanation of QR code technology, with direct interviews with the inventor and references to primary sources. The content is technically accurate and well-structured, though some simplifications are made for accessibility.

Chapters

Cited Sources

  • References page — Comprehensive list of references cited in the video.
  • 1940's grocery store — Historical footage of a grocery store in the 1940s, illustrating the checkout process before barcodes.
  • Alfred Vail portrait — Portrait of Alfred Vail, collaborator of Samuel Morse.
  • Bernard Silver portrait — Portrait of Bernard Silver, co-inventor of the barcode.
  • Norman Joseph Woodland portrait — Portrait of Norman Joseph Woodland, co-inventor of the barcode.
  • Masahiro Hara portrait — Portrait of Masahiro Hara, inventor of the QR code.
  • Damaged barcode 1 — Example of a damaged barcode, illustrating the need for error correction.
  • Damaged barcode 2 — Another example of a damaged barcode.
  • QR Code with Drones | Firefly Drone Show — Example of a QR code formed by drones, showing a creative application.
  • Testing a nano-barcodes marking technology — Academic paper on matrix codes, providing context on alternative 2D codes.
  • Snake in a QR code — Video of a computer game (Snake) encoded in a QR code, demonstrating data capacity.
  • Scratched CD — Image of a scratched CD, illustrating the need for error correction in optical media.
  • 5 needle telegraph — Image of a 5-needle telegraph, a precursor to Morse's simpler system.
  • NASA Celebrates 40 Years of the Voyager Mission — NASA page about Voyager mission, which used Reed-Solomon error correction.
  • Apollo footage — Apollo mission footage, used to illustrate the data capacity of QR codes.

Concurring Sources

External References

Contribution & Novelties

The video offers a unique hands-on approach to explaining QR code technology, making complex concepts accessible through a physical demonstration. It provides a clear and detailed explanation of Reed-Solomon error correction, which is often treated as a black box. The historical narrative, from Morse code to modern QR codes, provides valuable context. The interview with Masahiro Hara adds a personal dimension and insights into the design choices.

Pour aller plus loin :

  • Reed-Solomon error correction — Wikipedia article on the error correction method used in QR codes.
  • QR code — Wikipedia article on QR codes, including technical specifications and history.
  • Hamming distance — Wikipedia article on the concept of Hamming distance, fundamental to error detection and correction.
  • Galois field — Wikipedia article on finite fields, used in Reed-Solomon encoding.

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Radar Profile

The radar profile shows high scores across all dimensions, with particularly strong performance in information quality and reliability. The video is dense with accurate information, presented in an engaging and technically sound manner, making it an excellent educational resource.

Reliability 9/10

💬 Très positif. Sur les 30 commentaires analysés, les spectateurs expriment une admiration quasi unanime pour la clarté de l'explication, la qualité de la narration et l'aspect pratique de la construction d'un QR code, avec quelques remarques sur des erreurs de traduction dans l'interview.