LocalDrop (Veltrix) · P2P LAN File Transfer & Media Cinema

Experience the Native Architecture

Widescreen Living Room Cinema Player for laptops & TVs, and an edge-to-edge remote controller for mobile phones.

Desktop File Transfer Hub: Drag-and-drop zone, target peer selector, multi-file queue, and received files center. ● 78.4 MB/s LAN Speed Active

📤

Universal File Drop Zone

Drag and drop documents (PDF, Word), Android APKs, photos, lossless audio, and ZIP archives with no file size limits.

🛡️

On-the-Fly SHA-256 Checksums

Every 8 MB slice is hashed dynamically in memory. Corrupt bytes or aborted transfers are caught and reconciled immediately.

📥

Received Files Center

All files transferred over Wi-Fi appear in a dedicated download center with file extension badges and 1-click attachment downloads.

AirDrop Cinema Widescreen Player: Full 1400px widescreen TV playback with instant zero-wait range streaming and remote handoff. ● HTTP 206 Partial Content Stream

⚡

Zero-Wait Playback (<200ms)

HTTP 206 range streaming allows video to play on the receiving screen immediately without waiting for the full file download.

⏱️

Exact Frame Resume Memory

Pause on phone at 04:18 → switch to TV → continues playback from the exact second with zero position loss.

🎛️

On-Screen Cinema HUD Controls

Direct on-screen receiver controls: interactive scrubber, volume slider, +/-10s skip, subtitle switcher, and fullscreen.

Mobile File Transfer: Touch-optimized drop zone & file history.

Mobile Remote Controller: Silent remote controls TV screen.

🔇

Strict Single-Audio Routing

When casting to TV, the phone automatically mutes its local speaker to eliminate audio echo and duplicate sound.

🍎

iOS Safari WebKit Optimized

Built with webkit-playsinline, safe audio session unlocking, and tap-to-unmute prompts that prevent iOS audio ducking.

🔋

0% Background Battery Drain

Timestamps are written atomically to disk on pause. Zero 24/7 background CPU or RAM consumption when idle.

High-Performance Rust CLI & Core Engine

Written in Rust with Tokio async networking, Postcard binary framing, and streaming SHA-256 validation.

# Start receiver daemon on port 8080
cargo run --release -p localdrop_cli -- receive --port 8080 --out ./inbox

# Send any file over local network
cargo run --release -p localdrop_cli -- send 192.168.0.105:8080 ./path/to/movie.mp4

Payload Size	Chunk Size	Wall Clock Time	Measured Throughput	Memory Footprint	SHA-256 Integrity
100 MB	1 MB	1.36s	73.15 MB/s	< 25 MB RSS	Verified
1 GB	1 MB	14.23s	71.93 MB/s	< 25 MB RSS	Verified
Web LAN Slices	8 MB	Variable	78.40 MB/s	Zero-Copy Stream	Verified

Under the Hood Architecture

Engineered with rigorous networking guarantees, zero-copy buffers, and intelligent audio routing.

Data Pipeline

Dual-Mode Execution Flow

How bytes flow across the LAN for file drops versus live cinema streams:

FILES Drop Zone → 8 MB Slice Chunks → SHA-256 Checksum → SSE Broadcast → Received Files Center

STREAM Media File → HTTP 206 Range Stream → Frame Memory Atomic Cache → Target Screen HUD

HANDOFF Pause at 04:18 → Cache exact timestamp → Tap switch → Sub-200ms resume on TV

Audio Engineering

Single-Audio Source Routing

Eliminating the delayed repeated audio echo across sender and receiver:

PHONE Automatically muted (muted=true, volume=0) when streaming to TV. Functions as a silent controller.

TV Active speaker output with on-screen volume slider and mute controls.

IOS Optimized with webkit-playsinline and gesture-unlocked audio sessions to prevent audio ducking.

Reliability

Zero Cloud & Bounded Memory

Strict system guarantees across mobile devices and low-spec smart TVs:

RAM Flat < 25 MB RSS memory footprint. Never loads entire multi-gigabyte files into RAM.

BATTERY Timestamps written to non-volatile disk. Zero background daemon battery drain when idle.

SECURITY Strict path normalization protects against directory traversal and reserved OS device names.

🏆 Devpost Hackathon Submission Suite

The Story Behind LocalDrop (Veltrix)

Solving cross-platform file transfers and video streaming with zero cloud dependence.

💡 The Inspiration & The Anime Dilemma

LocalDrop started with a technical blueprint: a Rust-powered P2P file transfer engine with Tokio and streaming SHA-256 to escape cloud relays. But while building it, I ran into a personal frustration: I am a huge anime fan. I download episodes onto my phone, but watching on a tiny screen when a big TV is right there felt limiting. Searching for cables, enabling MTP, and waiting 15 minutes to copy a 3 GB anime episode killed the vibe. Then the breakthrough hit: Why wait for the whole file to transfer before pressing play? What if we stream video slices over the LAN so it plays immediately on the big screen, with exact frame memory?

⚡ The Dual-Engine Breakthrough

That epiphany transformed the project into a dual-engine architecture: 📁 P2P AirDrop File Transfer (78.4+ MB/s, multi-file queue, SHA-256 verification) + 🎬 AirDrop Cinema (HTTP 206 chunked range streaming, <200ms TTFP, and frame-accurate device handoff between phone and TV).

🛠️ How We Built It

The backend engine is engineered in Rust with Tokio asynchronous networking and Postcard binary framing. The presentation layer is a responsive Web PWA with pure CSS/JS, Server-Sent Events (SSE), and a standalone Android APK container.

🧗 Real Technical Hurdles Solved

We resolved the delayed audio echo bug using strict single-audio routing (the phone automatically mutes to act as a silent remote while the TV takes active audio); conquered iOS Safari WebKit autoplay policies with webkit-playsinline and gesture unlocking; and bounded RAM to $O(\text{chunk})$ with zero heap bloat.

🌟 Accomplishments We're Proud Of

Delivering 78.4 MB/s LAN throughput, sub-200ms frame-accurate resume memory, standalone APK v1.0, and 100% peer-to-peer privacy with zero external servers, cloud accounts, or 24/7 battery drain.

🔮 Future Horizons

QUIC transport integration, multi-peer synchronized anime watch parties on the local network, and automatic Wi-Fi Direct peer grouping when no shared router is present.

Deployment & GitHub Pages Guide

How to host this documentation on GitHub Pages and run LocalDrop on your own network.

Open Repo Settings

Go to your GitHub repository at github.com/Hellnight2005/Veltrix and click on the Settings tab.

Select Pages

In the left-hand sidebar under Code and automation, click on Pages.

Set Source to /docs

Under Build and deployment, set Source to Deploy from a branch. Select main or your active branch and folder /docs.

Save & Launch

Click Save. In 1–2 minutes, your live site will be live at https://hellnight2005.github.io/Veltrix/!

Run Web & Mobile Cinema App

cd apps/localdrop_web
npm install
npm run dev

Open http://localhost:5173/ for Widescreen Cinema Player, or switch to Mobile Remote on phone view.

Run Rust Core Daemon

cargo run --release -p localdrop_cli -- receive --port 8080 --out ./inbox

Starts high-performance TCP receiver daemon on port 8080 with streaming SHA-256 integrity verification.

🎨 Design Engineering Skills

npx skills add emilkowalski/skill

Installs Emil Kowalski's 15 design engineering & animation skills for building interfaces that feel right.

📚 Complete Documentation Hub

Detailed guides and technical references included in the repository:

README.md

Main repo overview & benchmarks

→

ARCHITECTURE.md

System layers, audio routing & API

→

PRODUCT_GUIDE.md

500-line exhaustive specification

→

DEPLOYMENT_GUIDE.md

Installation & Pages deploy guide

→

DEVPOST.md

Hackathon pitch & project story

→

LICENSE (MIT)

Open source license terms

→

AirDrop for Everyone. Cinema Stream for Everything.