ARCADE3

ARCADE3 — WHEP Streaming Cabinet

WebRTC/WHEP replaces the JPEG-over-WebSocket frame streaming from ARCADE2.

What changed

	ARCADE2	ARCADE3-WHEP
Video path	page.screenshot() JPEG → base64 → WS → <m-image> swap	ffmpeg rawvideo → wrtc RTCVideoSource → WebRTC → <m-video>
Audio path	ffmpeg Opus chunks → base64 → WS → MediaSource JS buffer	ffmpeg PCM → RTCAudioSource → WebRTC (same peer connection)
Transport	TCP WebSocket	UDP WebRTC
Latency	~200–500ms	~30–80ms
Screen flicker	Yes (image element swap per frame)	No (native video texture)
Input path	WS → server → Puppeteer (unchanged)	Same

How it works

Player presses E
  → cabinet opens WebSocket to /input?rom=...&session=SESSION_ID
  → server spawns Puppeteer + ffmpeg video + ffmpeg audio
  → server replies { type: "session_ready", whepUrl: "whep://server/stream/SESSION_ID" }
  → cabinet sets <m-video src="whep://...">
  → MML client POSTs SDP offer to https://server/stream/SESSION_ID
  → server feeds offer into RTCPeerConnection, returns SDP answer (201)
  → WebRTC handshake completes over UDP
  → video+audio stream appears on cabinet screen in ~1-2s
  → gamepad inputs flow: Gamepad API → WS → Puppeteer keyboard (unchanged)

Files

File	Purpose
server-whep.js	Main server — Puppeteer + ffmpeg + wrtc + WHEP endpoint + MML doc server
arcade-wario-whep.html	MML cabinet — <m-video> instead of <m-image> swap
Dockerfile	Chromium + ffmpeg + PulseAudio + wrtc deps
start.sh	Boots Xvfb + PulseAudio + Node
default.pa	PulseAudio virtual sink config
package.json	Adds @roamhq/wrtc to deps

Deploy to Railway

1. Push these files to your Arcade3 repo
2. Railway detects Dockerfile → builds automatically
3. After deploy, copy your Railway domain (e.g. arcade3-production.up.railway.app)
4. In arcade-wario-whep.html update:

   var SNES_SERVER_WS = "wss://arcade3-production.up.railway.app";
   

5. Commit and push — Railway redeploys

WHEP URL format

MML uses whep:// protocol which it converts to https:// for the SDP POST:

<m-video src="whep://arcade3-production.up.railway.app/stream/SESSION_ID">

becomes:

POST https://arcade3-production.up.railway.app/stream/SESSION_ID
Content-Type: application/sdp
Body: [SDP offer]

Response: 201 Created + SDP answer → WebRTC connected.

wrtc on Railway

@roamhq/wrtc ships prebuilt binaries for Linux x64 — Railway’s default environment. No compilation needed. It just works with npm install.

One session per player

Each player who presses E gets their own:

• Puppeteer browser instance
• ffmpeg video + audio capture process
• RTCPeerConnection

This is the same model as ARCADE2. Railway’s free tier handles ~2-3 concurrent sessions. Upgrade to a paid Railway plan for more concurrent players.