KDE Plasma Audio Pass-Through

A Plasma 6 widget that lets you route live audio from any available input device to any output device with a single click. Perfect for quick monitoring, ad-hoc routing, and accessibility scenarios.

Key Features

• Toggle pass-through instantly from your panel
• Keep your preferred input/output devices persistent across sessions
• Optional auto-start to enable routing as soon as Plasma loads
• Visual feedback: green when active, red on error, animated indicator while routing
• Friendly tooltips with device names and status
• Configurable widget size (24–128 px) to fit any panel layout
• Graceful handling of device changes and errors, with logging for debugging

Requirements

• KDE Plasma 6.0+
• PipeWire or PulseAudio (with the PulseAudio compatibility layer when using PipeWire)
• pactl available in PATH

Installation

One-liner

plasmapkg2 --install org.kde.plasma.audiopassthrough.plasmoid

(Generate the plasmoid package with plasmapkg2 --pack package --output org.kde.plasma.audiopassthrough.plasmoid if you prefer manual packaging.)

Using the included script

cd org.kde.plasma.audiopassthrough
./install.sh

Manual setup

mkdir -p ~/.local/share/plasma/plasmoids/org.kde.plasma.audiopassthrough
cp -r package/* ~/.local/share/plasma/plasmoids/org.kde.plasma.audiopassthrough/

Restart Plasma or log out/in if the widget list doesn’t refresh automatically.

Adding the Widget

1. Right-click your panel → Add Widgets…
2. Search for Audio Pass-Through
3. Drag it onto your panel and release

Configuration

Open Configure Audio Pass-Through… from the widget’s context menu to adjust:

• Input Device and Output Device (pulls live data from PipeWire/PulseAudio)
• Auto-start on load
• Widget width/height with live validation and reset-to-default option

Changing devices while pass-through is active will restart the loopback with the new selection.

How It Works

Under the hood the widget issues pactl load-module module-loopback source=<input> sink=<output> latency_msec=50. The module index is tracked so that pactl unload-module reverses routing cleanly. Errors are surfaced in the UI and logged to an internal debug file for easier troubleshooting.

Troubleshooting

• Please configure input and output devices first: open the config dialog and pick devices.
• Failed to enable …: usually indicates PipeWire/PulseAudio could not load the loopback module—check if the devices are in use elsewhere.
• Widget disappeared? Make sure you’re running Plasma 6 and refresh your panel: systemctl --user restart plasma-plasmashell.

Packaging for KDE Store

1. Update metadata.json with accurate Version, Website, and BugReportUrl values.
2. Run plasmapkg2 --pack package --output org.kde.plasma.audiopassthrough.plasmoid.
3. Prepare screenshots, changelog, and a short description.
4. Upload the .plasmoid archive to the KDE Store.

Development Notes

Project layout:

org.kde.plasma.audiopassthrough/
├── package/
│   ├── metadata.json
│   ├── contents/
│   │   ├── ui/
│   │   │   ├── main.qml
│   │   │   └── configGeneral.qml
│   │   └── config/
│   │       ├── config.qml
│   │       └── main.xml
├── install.sh
└── README.md (this file)

main.qml manages toggle logic, status UI, and loopback module handling. configGeneral.qml builds the device selection and sizing UI, issuing live pactl queries via Plasma’s DataSource executable engine.

License

Copyright © 2025

This program is free software: you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation, either version 3 of the License, or (at your option) any later version.

This program is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details.

You should have received a copy of the GNU General Public License along with this program. If not, see https://www.gnu.org/licenses/.