Quadrature

A four-channel audio player for broadcast studios, written in C with GTK4.

4-track audio player	Fast full-text search engine
Full artist, recording, and instrumentalist data via MusicBrainz	Library credits, appears-on, and featuring UI

Features

• 4-Channel Playback — independent transport, monitoring, and cue per channel
• Broadcast Console Integration — start/stop via GPIO, serial, and network
• Preview/PFL — monitor audio before going live
• Professional Formats — FFmpeg-based decoding (MP3, FLAC, WAV, OGG, AAC, BWF)
• Music Library — SQLite-backed with full-text search and MusicBrainz enrichment

Install

Flatpak (recommended for most users)

Download the bundle for your architecture from the latest release and install it directly:

# x86_64
wget https://github.com/elicbarbieri/quadrature/releases/latest/download/quadrature-x86_64.flatpak
flatpak install --user quadrature-x86_64.flatpak

# aarch64
wget https://github.com/elicbarbieri/quadrature/releases/latest/download/quadrature-aarch64.flatpak
flatpak install --user quadrature-aarch64.flatpak

Updates: re-download the latest bundle and run flatpak install --user

The Flatpak distribution only has the MusicBrainz REST API (rate-limited ≤0.91 req/sec) and AcoustID REST API (rate-limited ≤2.86 req/sec). For large libraries and self-hosted musicbrainz postgresql mirrors or self-hosted AcoustID, use the native build below.

Native build (studios, large libraries, low-latency)

Native builds avoid Flatpak's sandbox and FUSE overhead and can talk directly to a self-hosted MusicBrainz Postgres mirror — orders of magnitude faster than the public HTTP API for large library scans.

Recommended when:

• Library exceeds ~50,000 tracks
• Studio environment requiring tight audio latency (sub-5ms)
• You operate your own MusicBrainz mirror or AcoustID dataset

Install via Nix flakes:

# Install Nix
curl --proto '=https' --tlsv1.2 -L https://nixos.org/nix/install | sh -s -- --daemon

# Enable flakes (one-time, non-NixOS only)
mkdir -p ~/.config/nix && echo "experimental-features = nix-command flakes" >> ~/.config/nix/nix.conf

# Install
nix profile install github:elicbarbieri/quadrature

# Or run directly
nix run github:elicbarbieri/quadrature

Or build from source:

git clone https://github.com/elicbarbieri/quadrature.git
cd quadrature
nix develop
make production
sudo make install

Configuration

Settings are stored in ~/.config/quadrature/settings.ini (or ~/.var/app/org.quadrature.Player/config/quadrature/settings.ini under Flatpak).

MusicBrainz backend selection

Quadrature picks its MB backend automatically based on settings:

Configuration	Backend used
[MusicBrainz] pg_conninfo=host=... set (native build only)	PostgreSQL — direct queries to a self-hosted MB mirror
pg_conninfo empty or missing	HTTP — public musicbrainz.org REST API (1 req/sec)