⬡ polycast

Distributed immersive playback — replace Resolume Arena with a cluster of cheap nodes.

One mini PC per projector. Short HDMI. Long Ethernet. Pre-rendered video. Automatic sync. No expensive license.

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The Problem

Running a single pre-rendered video on loop for 4 months across 4 projectors shouldn't require:

• A R$15k workstation
• A R$2.5k Resolume Arena license
• Expensive fiber HDMI cables

Polycast is the alternative for fixed installations where the content is already rendered.

Architecture

authoring machine (Windows/Mac/Linux)
  └── polycast-export → splits master video into per-node slices

network (Ethernet)
  ├── master server → sync server + web dashboard
  ├── node-1 (mini PC) → mpv → projector 1 [HDMI]
  ├── node-2 (mini PC) → mpv → projector 2 [HDMI]
  ├── node-3 (mini PC) → mpv → projector 3 [HDMI]
  └── node-4 (mini PC) → mpv → projector 4 [HDMI]

Packages

Package	Description
@polycast/exporter	CLI: splits master video into node slices with baked edge blending
@polycast/node-agent	Daemon on each mini PC: controls mpv, syncs with master
@polycast/master	Sync server + web dashboard

Quick Start

1. Export content

npm install
node packages/exporter/src/index.js \
  --input master.mp4 \
  --config examples/aya-studio-4p.json \
  --output ./dist

2. Deploy to nodes

node packages/exporter/src/deploy.js \
  --config examples/aya-studio-4p.json \
  --dist ./dist \
  --user polycast

3. Start master

cd packages/master
npm install
npm start
# Dashboard at http://localhost:3000

4. Setup each node

See docs/setup-node.md for full Ubuntu setup guide.

# On each mini PC (Ubuntu 22.04)
sudo apt install mpv nodejs npm
git clone https://github.com/sztlink/polycast /opt/polycast/app
npm install --prefix /opt/polycast/app
# Edit /opt/polycast/config.json
sudo systemctl enable --now polycast-node

Layout Config

The layout.json defines your canvas and projector geometry:

{
  "canvas": { "width": 7200, "height": 1080, "fps": 25 },
  "master": { "host": "192.168.1.100", "port": 3001 },
  "nodes": [
    {
      "id": "node-1",
      "host": "192.168.1.101",
      "crop": { "x": 0, "y": 0, "w": 2080, "h": 1080 },
      "blend": { "right": 160 }
    }
  ]
}

See examples/aya-studio-4p.json for the full 4-projector AYA Studio layout.

Sync Model

• Software sync via WebSocket (no genlock/framelock hardware required)
• Master broadcasts timecode every 1s
• Nodes self-correct if drift > 200ms
• Typical drift in practice: 50–150ms — imperceptible for contemplative video

Edge Blending

Blend is baked into the exported video via ffmpeg geq filter:

• Linear luminance ramp at overlap zones
• No runtime processing on nodes (dumb players)
• Re-export needed if blend needs adjustment (usually once per installation)

Requirements

Component	Requirements
Exporter	Node.js 18+, ffmpeg in PATH
Node agent	Ubuntu 22.04+, Node.js 18+, mpv
Master	Node.js 18+, any OS

Hardware for AYA 4-Projector Setup

Recommended mini PC: Beelink S12 Pro (~R$800)

• Intel N100, 16GB RAM, 500GB SSD
• HDMI 2.0 output
• Fanless / low noise
• Proven at AYA (already used for kiosks)

4 nodes + switch + cables ≈ R$3.500 total vs. workstation + Arena license ≈ R$18.000+

Status

MVP — built for AYA Studio 4-projector installation, April 2026.

• Exporter with crop + blend
• Node agent with mpv IPC + watchdog
• Master sync server
• Web dashboard
• Field test with real projectors (pending hardware)

License

MIT — AYA Studio / Felipe Sztutman