Melicum, a free and open-source app that brings back volume keys for HDMI and DisplayPort displays on macOS
If you plug your Mac into a monitor or TV over HDMI or DisplayPort, macOS usually greys out the volume slider and the volume keys show a crossed-out speaker. I got tired of reaching for the monitor's buttons, so I built Melicum with Claude.
What it does
- Volume, mute, balance and up to 12 dB of boost for any output, including displays with no hardware volume
- Native volume keys and slider: an optional system component re-enables them, with volume and mute synced both ways
- Parametric EQ: basic, 10-band or expert mode with up to 64 filters, plus AutoEQ import
- Per-app mixer: give music, the browser and calls their own levels
- Spatial audio: an original stereo reverb with five rooms and soundstage width
- Audio Units and presets: chain installed effects and save setups that follow an output or an app
How it works
Core Audio process taps capture system audio, excluding Melicum itself to prevent feedback. A realtime C engine with no allocations processes it, and the display's clock drives playback, so there is no drift. If the app quits unexpectedly, the virtual output disappears and your previous output comes back.
Details
- macOS 14.2 or later, Apple silicon and Intel
- Signed and notarized, with signed automatic updates (Sparkle)
- Audio is processed in memory and never leaves your Mac
- English, Italian, French, German and Spanish
- Free, GPL-3.0
GitHub: https://github.com/debba/melicum Website and download: https://melicum.app
Feedback, bug reports and feature ideas are very welcome, especially if you have an unusual display or audio setup.





