Luma is a lightweight, multi-instance LV2 host for Linux designed for clarity, correctness, and debugging.

It supports real-world LV2 plugins including X11 and GTK2 user interfaces, advanced LV2 extensions such as data-access, and a fully functional terminal-based NO-GUI mode.

Luma is intentionally compact, readable, and suitable as both:

• a minimal plugin launcher
• a reference LV2 host implementation
• a development and debugging tool
• a headless LV2 runner
• a testbed for LV2 UI and Atom interaction

• Loads and runs LV2 plugins
• Multi-instance support
• Independent plugin engines
• JACK audio integration
• Proper LV2 feature negotiation
• Clean shutdown handling
• Signal-safe exit

• X11-based LV2 UIs
• GTK2-based LV2 UIs
• Drag and Drop support
• Resize handling
• UI idle interface support
• NO-GUI mode via terminal interface
• Basic terminal control interaction (accessibility-friendly)

Luma can run plugins entirely without graphical UI.
This makes it usable in:

• SSH sessions
• minimal desktop setups
• accessibility-driven workflows
• headless systems

• LV2 State extension
• LV2 Preset discovery and restore
• LV2 Worker extension
• LV2 Atom support
• LV2 data-access extension (required for Calf plugins)
• URID mapping and resolution
• Patch message handling
• Full feature injection system

Luma includes a dedicated debug mode using a DummyEngine.

In debug mode:

• The real JACK engine is replaced
• All Atom events (DSP → UI and UI → DSP) are logged
• Control change messages are printed
• Patch:Set messages are decoded
• URIDs are resolved to readable symbols
• Feature negotiation becomes visible

This makes Luma useful as:

• an LV2 debugging tool
• a development inspection host
• a protocol analysis tool

• Interactive terminal plugin browser
• Paged navigation
• Preset selection
• Search by name or URI
• Clean terminal restore on exit

• Linux
• JACK
• X11
• GTK2 (for GTK-based UIs)
• Lilv (LV2 host library)
• C++17 compatible compiler

Install dependencies (Debian/Ubuntu):

sudo apt install libjack-jackd2-dev liblilv-dev libx11-dev libgtk2.0-dev pkg-config

make

Manual:

g++ main.cpp -o luma \
    `pkg-config --cflags --libs jack lilv-0 x11 gtk+-2.0` \
    -ldl -pthread

Start Luma by passing:

./luma <string>

If no argument is provided:

./luma

You get an interactive plugin browser.

Controls:

• ENTER → next page
• ↑ / ↓ → page navigation
• number → select plugin
• q → quit

If presets are available:

[0] OrangeCrunch
[1] PreEQ

Select preset (ENTER = default):

• Enter number → load preset
• ENTER → default state

Each plugin instance consists of:

LV2Host
 ├── Engine (JACK or DummyEngine)
 ├── UI Backend (X11 / GTK2 / NO-GUI)
 ├── Worker Thread
 ├── Atom Buffers
 └── State / Preset Handling

Multiple instances are managed by:

MultiHost
 └── owns multiple LV2Host instances

Each plugin runs independently and can be routed freely via JACK (e.g. qjackctl).

Luma intentionally avoids becoming a DAW.

Instead, it focuses on:

• correctness over feature bloat
• minimal, readable code
• real-world LV2 compliance
• debugging visibility
• predictable behavior

It is designed as a compact and understandable reference host.

BSD-3-Clause

Luma is a compact LV2 host created as a reference implementation and experimentation platform.

Enjoy summoning your plugins 🧙