DeckLink AV Test Pattern Generator

Web interface to send video test patterns and audio tones to a Blackmagic DeckLink SDI output.

Built for macOS. Requires a custom FFmpeg build with DeckLink support — see installation below.

---

Color bars with logo overlay, NTP-synced clock and settings overlay

Main controls: background, text, logo, animations, video format, DeckLink device

8-channel audio: per-channel enable, ID cycle, 1-frame flash, 400Hz force

---

What it does

• Outputs test patterns to a DeckLink card via SDI
• Video formats: 1080i50, 1080i60, 1080p25/30, 720p50/60, 576i50
• Test sources: SMPTE bars, PAL bars, color bars, gradients, fractals, custom image upload
• 8-channel audio with configurable tone (frequency + level), ID cycling, 1-frame flash
• On-screen text, logo overlay (PNG upload), NTP-synchronized clock
• Preset save/load, real-time FFmpeg log, web monitor (HLS preview)
• Auto-start on server launch via env var

---

Requirements

• macOS (Catalina or later)
• Blackmagic Desktop Video drivers — download here
• A DeckLink card connected (UltraStudio, Mini Monitor, etc.)
• FFmpeg compiled with --enable-decklink — see below
• Node.js >= 18

---

FFmpeg

The Homebrew FFmpeg does not include DeckLink support. You need to compile it yourself.

1. Download the Blackmagic DeckLink SDK (free, same support page as the drivers above).

2. Compile FFmpeg:

./configure \
  --enable-gpl \
  --enable-nonfree \
  --enable-decklink \
  --enable-libfreetype \
  --enable-libfontconfig \
  --extra-cflags="-I/path/to/decklink-sdk/include" \
  --extra-ldflags="-F/Library/Frameworks -framework DeckLinkAPI"
make -j$(sysctl -n hw.ncpu)

Compilation takes 15–30 minutes. Put the binary somewhere stable (e.g. ~/ffmpeg-4.4.4/build/bin/ffmpeg) and set FFMPEG_PATH in .env.

Verify DeckLink support:

ffmpeg -hide_banner -sinks decklink
# Should list your connected card

---

Install

git clone https://github.com/stephanebhiri/decklink-AV-test-pattern-generator.git
cd decklink-AV-test-pattern-generator
bash install.sh

The script checks Node.js, installs npm dependencies, verifies FFmpeg and drivers, and creates a .env template.

---

Configuration

Edit web-interface/.env (created by install.sh):

# Path to your FFmpeg binary (required, must have DeckLink support)
FFMPEG_PATH=/path/to/ffmpeg

# Path to your logo PNG (optional, transparent background recommended)
LOGO_PATH=/path/to/logo.png

# Server port (default: 3000)
PORT=3000

# Auto-start broadcast when the server starts
AUTO_START_BROADCAST=false
AUTO_START_DELAY_MS=5000

---

Run

cd web-interface
node server.js

Open http://localhost:3000.

---

Notes

• Tested with UltraStudio Mini Monitor and UltraStudio 4K
• NTP sync runs on startup and every 15 minutes (Cloudflare, Google, NIST)
• Uploaded logos and backgrounds persist in web-interface/uploads/
• FFmpeg logs stream live in the web UI
• SIGINT and SIGTERM both cleanly stop the FFmpeg child process

---

Troubleshooting

"Unknown input format: decklink" — FFmpeg was compiled without --enable-decklink.

No DeckLink sinks detected — Check that Desktop Video is installed, the card is connected, and run ffmpeg -hide_banner -sinks decklink.

Blank output / crash on start — Check the FFmpeg log in the web UI. Usually a format mismatch with the card.