Halo

A DJ app with a built-in lighting console.

About

⭕️ Halo is a DJ app with a built-in lighting console, designed for solo performers who want to deliver immersive live shows.

Mix across two decks while Halo drives the lighting rig in sync with your set. Lighting cues can be prepared per track, then shaped and overridden live from a console-style programmer—so one performer can control the music, the lights, and the energy of the room from a single app, without relying on a dedicated lighting operator.

Halo is designed to integrate seamlessly with the Ableton Push 2, providing hands-on real-time control and visual feedback without forcing you to perform through a mouse and keyboard.

Built for macOS in Rust, Halo uses the timestretch engine for real-time tempo and pitch control.

Warning

This project is still in heavy development and unsuitable for production use (even though I'm using it for shows).

Features

DJ

• Dual decks powered by one timestretch engine each: warm-start seeks, gapless loop wrap, and keylocked tempo control.
• Full mixer chain per deck: trim → 3-band isolator EQ (full-kill) → resonant LP/HP filter → channel fader, into a constant-power crossfader, master fader, and soft limiter.
• CDJ-style transport: play/pause and cue (set while paused, hold to preview, release to return).
• Hot cues — 8 per deck, with Normal and Gated modes and optional quantize to the beat grid.
• Loops — manual in/out, 4-beat quantized autoloop, and halve/double controls from 1/16 up to 16 beats.
• Tempo & sync — tempo slider with ±8/±16/±50% ranges, keylock, pitch-bend nudges, and one-button sync that locks BPM and beat phase to a master deck.
• Audible scrub with momentum — grab the waveform and hear it, like dragging a platter.
• Rich waveforms — 3-band RGB overview strip and a zoomed, centered-playhead view with beat/bar marks, rendered from background track analysis.
• Track library — SQLite-backed browser with playlists, search, sortable columns (BPM, key, duration, …), folder import, and background analysis. BPM comes from analysis; musical key is read from file tags.
• Prepare & Perform views — audition tracks on an independent third channel and edit cues in Prepare, then play the show in Perform.
• Meters everywhere — per-deck and master levels plus an audio-callback CPU meter.

Lighting

• Per-track cue lanes (Lighting / Pixels / FX) under the waveforms, edited directly and persisted in the library alongside the track.
• Console-style programmer — fixture grid, group selects, and Intensity/Color/Position/Beam/Pixel FX views with beat-synced effects; latch or flash overrides sit above track cues, with STORE-from-live.
• Real fixture engine — a default rig patched from real fixture profiles, editable live in the PATCH tab (profile, universe, address, grid position) and persisted to the library.
• Art-Net output — a dedicated 44 Hz engine thread resolves cues + programmer state into per-universe DMX frames and sends them over Art-Net (broadcast or unicast to a node), independent of the UI.

See ROADMAP.md for the full feature arc and what's next.

Requirements

• macOS 12+ (Core Audio via cpal; the UI uses the wgpu backend)
• Rust toolchain (stable for building/testing; nightly only for cargo +nightly fmt)
• timestretch-rs cloned alongside this repo (path dependency)
• Optional: an Art-Net node and DMX fixtures for the lighting rig

Installation

Halo depends on the timestretch crate by local path, so clone the two repos side by side:

git clone https://github.com/robmorgan/halo.git
git clone https://github.com/robmorgan/timestretch-rs.git
cd halo
cargo build --release

To build a macOS app bundle (Halo.app):

cargo install cargo-bundle
cargo bundle --release

Usage

cargo run --release

Load tracks through the in-app library or file dialog, or pass a file directly to load it on launch:

cargo run --release -- path/to/track.mp3

• Prepare view — import folders into the library, build playlists, audition tracks, and edit per-track lighting cues.
• Perform view — two decks, mixer, and the lighting programmer.
• Art-Net — configure broadcast or unicast-to-node output in the in-app settings window; the choice is persisted with the library.
• Logs — set RUST_LOG=debug (or another filter) when launching from a terminal.

Documentation

• ROADMAP.md — architecture overview, phased feature plan, and current status.

License

Halo is licensed under the Fair Core License, Version 1.0, ALv2.

Contributing

Contributions are welcome! Please feel free to submit a Pull Request.