为什么值得关注

它演示了一种实用的无网络文件传输方式，无需应用或配对，并分享了针对浏览器兼容性和鲁棒解码的硬核细节。

适合谁使用

探索离线数据传输方法的开发者
研究光通信与喷泉编码的研究人员
构建气隙或安全敏感系统的创客
寻求无追踪本地传输的隐私倡导者

典型使用场景

在无网络连接的两台设备间传输文件
在气隙环境中安全交换敏感数据
用喷泉编码原型化并测试光通信信道
展示二维码流与浏览器视觉API的交互式教学示例

项目优势

无需网络、应用或权限（仅需摄像头访问）
喷泉编码保证即使丢帧也能正确解码；接收者可中途加入
自描述帧实现自动会话恢复与重启
MIT开源许可，附带详细实现说明

使用前须知

概念验证，吞吐量有限（仅支持512KB或2MB图像）
需要明亮屏幕、稳定摄像头和HTTPS；iOS摄像头帧率存在兼容性问题
QR纠错等级设为最低（L）——依赖喷泉层处理擦除而非纠正错误

README 快速开始

Decimen Optical Transfer: fountain-coded QR file transfer

Send a file between two devices using nothing but a screen and a camera. One page displays the file as an endless stream of animated QR codes; another device points its camera at it and reconstructs the file. No network path between the devices, no app, no pairing, no permissions beyond the camera. The payload travels as light.

This is a minimal proof of concept extracted from a larger experiment that reached 128 KB/s phone-to-phone with denser frames, multi-code grids, and an error-corrected color channel. This PoC keeps only the essential trick and transmits a 512 KB image (or a 2 MB one, selectable in the sender's settings) at a comfortable rate.

Mid-transfer: a phone pulling a 2 MB image out of the air at 129 KB/s.

Try it

npm install
npm run dev

On the sending device (a laptop is ideal): open https://localhost:5173/send/ and it starts streaming immediately. Max screen brightness helps.
On the receiving device (a phone): open the Network URL Vite prints (https://:5173/receive/), accept the certificate warning once, tap Start camera, and point it at the code.
A few seconds later: Transfer Complete! and the received image, verified by hash.

Why the dev server is https-only: the receiver uses getUserMedia, and browsers remove that API entirely on insecure origins: a phone reaching your dev server over plain http has no camera, full stop (localhost is exempt, but your phone isn't localhost). That's a web platform rule, not a choice. The dev server therefore ships with a self-signed certificate (@vitejs/plugin-basic-ssl); the browser will warn on first visit. Tap "Show Details" then "visit this website" (iOS) or "Advanced" then "Proceed" (Android/desktop), and the page is still a secure context, so the camera works. The odd-looking lvh.me hosts Vite prints are a public convenience domain that resolves to 127.0.0.1 (same machine, nothing extra running).

Hold the phone steady, or better, prop it against something. Camera autofocus hunting from hand tremor is the #1 throughput killer.

How it works

The one-way channel problem. A screen-to-camera link has no back-channel: the receiver can't ask for retransmission, and it will inevitably miss frames (blur, refresh straddling, autofocus). Looping the frames and h

decimen-optical-transfer