EqualizerCast

EqualizerCast is a small, dependency-free web control panel for a Liquidsoap equalizer running in AzuraCast. Band count, frequency, Q, gain, and output changes reach the stream immediately and are persisted locally. It includes more than 40 built-in presets and a sweepable sine tone that overlays the music and automatically stops after 30 seconds.

Safety and privacy

• The server binds to 127.0.0.1 by default. Put authentication in front of it before exposing it through a reverse proxy.
• The request header used by the browser is a CSRF guard, not authentication.
• Keep the Liquidsoap API key in a root-readable file or environment variable.
• Runtime settings, snapshots, .env, logs, database data, and keys are ignored by Git. No station-specific credentials or data are included in this repo.
• The tone is transmitted on air. It is capped by Liquidsoap and automatically disabled after 30 seconds and after every service restart.

Requirements

• AzuraCast with Liquidsoap's HTTP/telnet bridge enabled
• Liquidsoap 2.4 or newer
• Python 3.11 or newer
• Docker access for the service account, if using automatic container discovery

Install

1. Add the generated Liquidsoap block after your station's combined radio source exists and before its encoders:

   python3 generate_liquidsoap.py > equalizercast.liq
   

   Copy the contents into AzuraCast's custom Liquidsoap configuration. The generated block creates the interactive variables expected by the web app.

2. Store the Liquidsoap API key without a trailing newline:

   sudo install -d -m 750 /etc/equalizercast
   sudo install -m 600 /dev/null /etc/equalizercast/liquidsoap-api-key
   sudoedit /etc/equalizercast/liquidsoap-api-key
   

   Paste only the key into the editor. This keeps it out of shell history.

3. Install and adapt the example service:

   sudo cp examples/equalizercast.service /etc/systemd/system/
   sudo systemctl daemon-reload
   sudo systemctl enable --now equalizercast
   

4. Reverse proxy http://127.0.0.1:8767 behind your existing authenticated admin site. Do not expose the loopback service directly to the public.

Configuration

controls.json defines the installed band curve and safe customization ranges. The web panel can use 1–32 bands, edit every center frequency and Q, and apply a preset either to the current layout or to the standard 10-band layout. presets.json contains the built-in preset curves and their research provenance. The curves were newly authored within the app's conservative ±6 dB range; the referenced Audacious/Winamp collection and AWA guide were used for established names and intended tonal profiles, not copied gain data. Presets may also contain a complete bands layout and an optional output_gain; these exact-layout presets restore band count, frequencies, Q, gains, and output instead of interpolating onto the current layout.

Changing from an earlier EqualizerCast release requires regenerating and replacing the Liquidsoap block once. The new block creates a 32-slot filter pool whose active count, frequency, gain, and Q are runtime controls. After that, layout changes do not require another regeneration or a Liquidsoap restart.

The app accepts these environment variables:

Variable	Default	Purpose
LIQUIDSOAP_API_KEY_FILE	/etc/equalizercast/liquidsoap-api-key	Root-readable key file
LIQUIDSOAP_API_KEY	unset	Direct key; useful for containers, less ideal on a host
LIQUIDSOAP_API_URL	auto-discovered	Complete /telnet endpoint override
AZURACAST_CONTAINER	azuracast	Container used for IP discovery
LIQUIDSOAP_API_PORT	8004	Liquidsoap bridge port
EQUALIZERCAST_STATE_DIR	/var/lib/equalizercast	Persistent settings directory
EQUALIZERCAST_HOST	127.0.0.1	Web bind address
EQUALIZERCAST_PORT	8767	Web port

Test

python3 -m unittest discover -s tests
python3 -m py_compile app.py generate_liquidsoap.py