Knoby

Control Elgato Wave Link channel volume with your keyboard's volume knob.

A tiny Windows tray app (Rust, ~650 KB, no installer) that turns a rotary encoder on a QMK / VIA keyboard into a per-channel volume knob for Elgato Wave Link: turn for volume, click to mute, double-click to pick which channel you are controlling.

Why

A keyboard volume knob sends the standard media keys, so it only moves the Windows master volume. If you mix with Wave Link (and maybe a Stream Deck) you want the knob to drive the channel you are actually listening to: music, game, browser or voice chat. Knoby makes that happen.

Features

• Per-channel volume on any Wave Link software channel: turn for volume, click to mute / unmute.
• Channel picker: double-click the knob, turn to move between your channel icons, click to confirm. An unobtrusive overlay slides in at a screen corner and never steals focus, so it is safe to use mid-game.
• Always in sync: stays consistent with Wave Link and Stream Deck, with no polling.
• Your channels, your icons: names, colours and icons come straight from Wave Link, and new channels show up automatically.
• Tiny and quiet: ~650 KB, ~13 MB of RAM, about 0.3% of one core when idle.
• Tray icon with status, Start with Windows, Open config file, Reload config and Quit.
• Configurable: volume step, picker speed, double-click timing, overlay corner and margin.

Quick start

1. Install Elgato Wave Link 3 and create the channels you want.

2. In VIA (or QMK), map the knob to unused keys:

   Knob	Key
   counter-clockwise	F14
   clockwise	F15
   click	F13

3. Download knoby.exe (or the .zip) from the latest release and run it. There is no window: look for the knob icon in the notification area.

4. Turn the knob. Double-click to open the channel picker.

Tip: use the tray menu to enable Start with Windows. Move knoby.exe to a permanent folder first: the startup entry points at the file you ran.

The executable is not code-signed, so Windows SmartScreen may warn the first time you run a downloaded copy.

How it works

• A global low-level keyboard hook (WH_KEYBOARD_LL) intercepts the three knob keys, so the system volume never moves.
• Wave Link is controlled through the local JSON-RPC WebSocket it exposes: Knoby reads the channel list (names, levels, icons) and writes level / isMuted. It follows channelChanged notifications to stay in sync with any other controller.
• The overlay is a software-rendered layered window (per-pixel alpha, anti-aliased, animated) with no GPU or UI framework, which keeps the binary tiny. The selection ring takes the colour of the selected icon.

Deeper dive, including the verified Wave Link protocol notes and the decisions made along the way, in docs/DESIGN.md.

Configuration

Settings live in %APPDATA%\Knoby\config.toml, created with commented defaults on first run. Use the tray menu: Open config file to edit it, Reload config to apply changes without restarting.

Setting	Default	Meaning
volume_step	3	Volume change per knob detent, in percent (1-20)
select_detents	1	Detents needed to move the picker by one icon (1-6); 1 = every detent moves one icon
select_min_ms	90	Speed limit: detents sooner than this after the last move are ignored (0-500)
double_click_ms	250	Double-click window; a single click (mute) fires after this delay (100-600)
select_timeout_ms	4000	The picker closes after this long without input (1000-15000)
overlay_corner	"top-right"	top-right, top-left, bottom-right or bottom-left
overlay_margin	24	Distance from the screen edge, in pixels (0-200)

Invalid values are ignored (the default is used) and reported on stderr in debug builds.

Build from source

Requires a recent stable Rust toolchain (MSVC) on Windows.

cargo build --release     # target\release\knoby.exe, no console window
cargo run                 # debug build: keeps the console for logging
cargo test

Developer switches (environment variables): KNOBY_DEBUG=1 logs every intercepted key, KNOBY_PREVIEW=<file.png> opens the overlay and saves one frame, KNOBY_ACCEPT_INJECTED=1 lets scripted key presses drive Knoby (used for automated testing).

Compatibility and limitations

• Windows 11 and Elgato Wave Link 3.x (developed against 3.4.0). Wave Link 2 uses a different protocol.
• The Wave Link WebSocket protocol is not covered by a public stability guarantee, so a future Wave Link update could require changes.
• The overlay is a topmost, non-activating window: it is designed to show over windowed and borderless games, but exclusive fullscreen is not guaranteed.

Related topics

Elgato Wave Link, volume knob, rotary encoder, QMK, VIA, custom keyboard, Stream Deck, per-app volume control, audio mixer, Windows tray utility, Win32, low-level keyboard hook, Rust.

Important

Disclaimer: Knoby is an independent project and is not affiliated with or endorsed by Elgato or Corsair. Wave Link and Stream Deck are trademarks of their respective owners.

License

MIT © 2026 Flavio De Musso.