MIDI Global Hotkey

A tiny experimental app that sends a MIDI CC toggle on a global hotkey — works even when your DAW has focus.

The Problem

MetricAB is a VST that lets you A/B compare your mix against reference tracks. Its toggle button is inside Cubase, meaning you can't bind it to a system-wide hotkey. Every time you want to switch reference tracks mid-session you have to click into the plugin. This app solves that by sending a MIDI CC message that MetricAB (or any VST) can map to a parameter.

It's worth noting that this is not required for Ableton Live which has awesome keyboard binding support.

How It Works

1. The app registers a global hotkey that fires system-wide, even when Cubase is in focus.
2. On each press it toggles a MIDI CC message (channel 1, CC 102, value 127/0) to a virtual MIDI port.
3. Cubase picks that up via a Remote Control Surface and forwards it to MetricAB.

Setup

Virtual MIDI Port

You need a virtual MIDI port for the app to send messages through.

• macOS: Enable the built-in IAC Driver in Audio MIDI Setup → MIDI Studio.
• Windows: loopMIDI is a free option.
• Linux: Use a virtual ALSA or JACK port.

DAW Setup (Cubase + MetricAB)

1. In the app, select your virtual MIDI port as the output.
2. In Cubase, create a Remote Control Surface (Studio → Studio Setup → Remote Devices) pointing at the same virtual port.
3. Map CC 102 on the surface to MetricAB's A/B toggle via MIDI learn.

Other DAWs

🤷🏻

Usage

• Default hotkey: Cmd+Shift+M (Mac) / Ctrl+Shift+M (Windows/Linux)
• Click the hotkey badge in the UI to rebind it — press your new combo, then Enter to confirm or Esc to cancel.
• Select your MIDI output from the dropdown. Settings are saved across restarts.

Building from Source

Requires Rust + Cargo and Node.js.

npm install
npm run tauri build

For development with hot reload:

npm run tauri dev

Tech Stack

• Tauri 2 — native app shell (Rust backend)
• React + TypeScript — UI
• midir — MIDI output
• tauri-plugin-global-shortcut — system-wide hotkey registration
• tauri-plugin-store — persistent settings

License

MPL-2.0