VLC DeckLink Plugin

A Rust-based VLC video output plugin for Blackmagic DeckLink devices, specifically targeting the Intensity Pro 4K.

Overview

This plugin enables VLC media player to output video through Blackmagic DeckLink capture/playback cards. It's designed for professional video workflows requiring SDI or HDMI output to external monitors, broadcast equipment, or video routers.

Hardware Support

• Primary Target: Blackmagic Design Intensity Pro 4K (PCIe)
• Other DeckLink Cards: Should work with other DeckLink devices that support video output

Features

• Video Output: Send VLC video to DeckLink HDMI/SDI outputs
• Multiple Resolutions: Support for SD, HD, and 4K output modes
• Pixel Formats: UYVY 8-bit, v210 10-bit, ARGB, BGRA
• Scheduled Playback: Frame-accurate video output timing
• Frame Buffering: Configurable buffer pool for smooth playback

Requirements

• Docker: All builds run inside Docker containers for reproducibility
• Blackmagic DeckLink SDK 15.3: Automatically downloaded during Docker build
• Make: For running build commands

Installation

Download the SDK from https://www.blackmagicdesign.com/developer/products/capture-and-playback/sdk-and-software into the root of this repository.

# Install release build (requires root)
make release

# Copy the plugin to /usr/lib/vlc/plugins/video_output/

GStreamer Plugin

The workspace also builds libgstrsdecklink.so, a GStreamer plugin providing the rsdecklinkvideosink video sink element (named distinctly from gst-plugins-bad's stock decklinkvideosink so both can coexist). It accepts UYVY, BGRA and ARGB at any resolution and scales to the best card mode.

# Build (same `make release`), then install for the current user:
make install-gst-local        # ~/.local/share/gstreamer-1.0/plugins/
# or system-wide:
sudo make install-gst         # /usr/lib/<arch>/gstreamer-1.0/

# Smoke test inside Docker (no card needed):
make gst-inspect

# Test pattern to the card:
gst-launch-1.0 videotestsrc ! video/x-raw,format=UYVY,width=1920,height=1080,framerate=30/1 ! rsdecklinkvideosink

# As UxPlay's video sink (AirPlay -> DeckLink):
uxplay -vs rsdecklinkvideosink

Element properties: device-index, device-name, mode (auto/1080p60/…), scaling (nearest/bilinear/bicubic/lanczos/lanczos-gpu), position (center/fit-width/fit-height/stretch/corners), buffer-count, gpu, gpu-device, db-path. GPU zero-copy scaling engages with scaling=lanczos-gpu and BGRA input; everything else uses the CPU scaler. Video only for now — the decklink crate has no audio output API yet.

Control Plane (decklink-gui)

A SQLite database is the interface between the GStreamer sink and decklink-gui, a native desktop control panel. Settings saved in the GUI override the element properties and are re-applied live — the running sink notices the change and reopens the output without a pipeline restart (this is also the only way to configure the sink under uxplay -vs, which cannot pass element properties). The sink writes status, per-second metrics (fps, frame time, GPU time), logs, the hardware inventory and — every ~2 s — preview thumbnails of the incoming frame and the composed frame sent to the card, back to the same database; the GUI renders them in Settings / Preview / Devices / Metrics / Logs / Status tabs.

make gui            # build the GUI on the host (SDK-free, needs GL/X11 only)
make run-gui        # launch it
make scan           # inventory the cards + probe supported modes into the DB
                    # (docker-built binary, runs on the host with the card)

The database lives at $DECKLINK_DB or $XDG_STATE_HOME/decklink/decklink.db (local filesystem required — WAL). The sink's db-path property overrides it; db-path="" disables the control plane entirely, restoring pure property-driven behavior. One sink per database: point concurrent sinks at different db-paths.

Architecture

The repository is a Cargo workspace with six crates:

• crates/decklink — a reusable, VLC-free DeckLink output library: device discovery, display-mode selection, frame pools, scheduled playback, pixel formats, subtitle blending and CPU scaling. GPU scaling (wgpu compute Lanczos + Linux DMA-BUF zero-copy) is behind the optional gpu cargo feature. DeckLinkDisplay is the high-level entry point.
• crates/vlc-decklink-plugin — the VLC plugin: module descriptor and config helpers (ffi/vlc_module.c), the vout_display_t entry points (plugin.rs) and VLC error mapping. Builds the libdecklink_plugin.so cdylib that VLC loads.
• crates/gst-decklink-plugin — the GStreamer plugin: a GstVideoSink subclass (videosink/imp.rs) driving DeckLinkDisplay, registered as rsdecklinkvideosink. Builds the libgstrsdecklink.so cdylib that GStreamer loads. Its videosink/db.rs worker thread connects the sink to the control-plane database.
• crates/decklink-db — the SQLite control plane: schema, typed API (settings/status/metrics/logs/devices/commands) and the string vocabulary shared by producers and the GUI. SDK-free.
• crates/decklink-gui — the eframe/egui control panel. Depends only on decklink-db, so it builds anywhere (make gui).
• crates/decklink-scan — small CLI that writes the device inventory and mode-support grid into the database without a running pipeline (make scan; --watch services rescan requests from the GUI).

Other applications can reuse the core library without VLC, e.g.:

[dependencies]
decklink = { git = "https://github.com/simukka/vlc-decklink", features = ["gpu"] }

┌─────────────────────────────────────────────────────────────┐
│                      VLC Media Player                        │
└─────────────────────────────────────────────────────────────┘
                              │
                              ▼
┌─────────────────────────────────────────────────────────────┐
│              VLC Video Output Plugin API                     │
│                  (vout_display_t)                            │
└─────────────────────────────────────────────────────────────┘
                              │
                              ▼
┌─────────────────────────────────────────────────────────────┐
│         crates/vlc-decklink-plugin (VLC glue)                │
│  ┌────────────┐  ┌──────────────┐  ┌────────────────────┐   │
│  │  plugin.rs │  │ vlc_module.c │  │  error.rs (codes)  │   │
│  │  (entry)   │  │ (descriptor) │  │                    │   │
│  └────────────┘  └──────────────┘  └────────────────────┘   │
└─────────────────────────────────────────────────────────────┘
                              │
                              ▼
┌─────────────────────────────────────────────────────────────┐
│           crates/decklink (reusable library)                 │
│  ┌─────────────┐  ┌─────────────────────────────────────┐   │
│  │ display.rs  │──│  device.rs │ output.rs │ frame.rs   │   │
│  │ (high-level)│  │  blend.rs  │ scaling.rs │ gpu/      │   │
│  └─────────────┘  └─────────────────────────────────────┘   │
│                         │                                    │
│                         ▼                                    │
│  ┌──────────────────────────────────────────────────────┐   │
│  │              FFI Layer (ffi/)                         │   │
│  │   C wrapper for DeckLink C++ SDK                      │   │
│  └──────────────────────────────────────────────────────┘   │
└─────────────────────────────────────────────────────────────┘
                              │
                              ▼
┌─────────────────────────────────────────────────────────────┐
│              Blackmagic DeckLink SDK (C++)                   │
└─────────────────────────────────────────────────────────────┘
                              │
                              ▼
┌─────────────────────────────────────────────────────────────┐
│                  Intensity Pro 4K Hardware                   │
│                      (PCIe 42:00.0)                          │
└─────────────────────────────────────────────────────────────┘

Technical Details

• Rust Edition: 2021
• DeckLink SDK: 15.3 (Linux)
• VLC API: 3.0 plugin interface
• FFI: bindgen for Rust bindings, C++ wrapper for DeckLink COM API

License

This project is licensed under the LGPL-2.1-or-later license, compatible with VLC's licensing requirements.

Acknowledgments

• VLC media player team
• Blackmagic Design for the DeckLink SDK
• The Rust community