Frame-Jack

Low-latency browser-based game streaming over LAN. Captures raw GPU frames via DirectX 11 hook, encodes with NVENC H.264, and delivers via WebRTC — no cloud provider, no SDK dependencies.

Architecture

Demo

Overview

Spec	Implementation
Capture	DirectX 11 API hook (MinHook)
Transport	Named Pipe → FFmpeg → WebRTC
Latency Target	< 50ms end-to-end
Input	Virtual Xbox 360 controller (ViGEm)

Tech Stack

Capture & Injection

Encoding & Transport

Input & Hardware

Client

Architecture

Frame Capture (dllmain.cpp)

• Injects into game process via LoadLibraryW remote thread
• Hooks IDXGISwapChain::Present (vtable index 8) using MinHook
• Copies back buffer → staging texture → CPU-mapped RGBA
• Lock-free ring buffer (3 slots, atomic) for frame queuing
• Consumer thread serializes to Named Pipe with 40-byte header

FrameHeader Structure (40 bytes, packed): magic(4) | headerSize(4) | frameId(8) | writeTimeNs(8) | width(4) | height(4) | rowPitch(4) | payloadSize(4) plain Copy

Streaming Server (index.js)

• Parses binary pipe stream by magic number (0x4D415246)
• 4-frame queue priming prevents encoder starvation
• FFmpeg NVENC: RGBA stdin → RTP/UDP (127.0.0.1:5000)
• UDP intercept rewrites SSRC, forwards via WebRTC SRTP
• Socket.IO signaling (offer/answer/ICE)
• ViGEm virtual controller for input injection

Browser Client

• RTCPeerConnection with forced H264 (profile-level-id=42e02a)
• playoutDelayHint = 0 for minimal buffering
• Unreliable DataChannel (maxRetransmits: 0) for input
• Vanilla JS + HTML5 <video>

Quick Start

Requirements

• Windows 10/11 x64
• NVIDIA GPU (NVENC support)
• Node.js 18+
• ViGEm Bus Driver
• Visual Studio 2022

Build

# Build capture DLL and injector
msbuild dll/Dx11Hook/Dx11Hook.sln /p:Configuration=Debug /p:Platform=x64
msbuild Injector/injector/injector.sln /p:Configuration=Debug /p:Platform=x64
Run
bash
Copy
cd backend
npm install
# Run as Administrator (required for ViGEm)
node index.js
Open http://127.0.0.1:3000

RUN

cd backend
npm install
# Run as Administrator (required for ViGEm)
node index.js

Limitations

• LAN only — no STUN/TURN implementation
• Single client — no reconnection handling
• Timing — cyclic stutter every 3-5s (keyframe/RTP reorder investigation pending)