https://github.com/rahix/pavu-mixer

"Hardware Mixer" for PulseAudio
https://github.com/rahix/pavu-mixer

Last synced: over 1 year ago
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"Hardware Mixer" for PulseAudio

• Host: GitHub
• URL: https://github.com/rahix/pavu-mixer
• Owner: Rahix
• License: other
• Created: 2021-08-16T10:28:12.000Z (almost 5 years ago)
• Default Branch: main
• Last Pushed: 2025-01-05T02:35:25.000Z (over 1 year ago)
• Last Synced: 2025-03-14T18:59:55.683Z (over 1 year ago)
• Language: Rust
• Homepage:
• Size: 28.2 MB
• Stars: 15
• Watchers: 3
• Forks: 2
• Open Issues: 8
• Metadata Files:
  • Readme: README.md
  • License: LICENSE-HARDWARE

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README

          
![](Eyecandy/Logo.svg) Pavu Mixer

=================================

_Pavu Mixer_ is a hardware mixing desk for controlling

[PulseAudio](https://www.freedesktop.org/wiki/Software/PulseAudio/) streams on

a connected computer.  Think of it as a hardware version of

[`pavucontrol`](https://freedesktop.org/software/pulseaudio/pavucontrol/).

![Pavu Mixer in Action](Eyecandy/Picture.jpg)

More pictures in [`Eyecandy/`](./Eyecandy).

### Hardware

The _Pavu Mixer_ is currently just a PCB fitted as the front plate of a

[console enclosure][enclosure].  This remedies the need for a custom front

plate.  Beneath it, an [STM32F3DISCOVERY][discovery] eval board is used as the

controller.  Connection to the computer is done over USB.

Following are the capabilities of the current hardware:

- 4 "Application Channels" + 1 "Main" Channel

- [240x240 LCD Display][display-board] (driver available in

  [`waveshare-display/`](./waveshare-display) subdirectory)

- Per channel:

  - Mono Volume Fader

  - Mute Button with green/red indicator LED

  - LED as brightness-based level indicator

  - Red LED as status indicator

- For the main channel, the level indicator is a 20 segment LED-bargraph

  instead.

- USB-B socket for connection to the computer

[enclosure]: https://www.tekoenclosures.com/en/products/family/PU/series/pult-36

[discovery]: https://www.st.com/en/evaluation-tools/stm32f3discovery.html

[display-board]: https://www.waveshare.com/wiki/1.3inch_LCD_Module

### Firmware/Software

The firmware on the [STM32F3DISCOVERY][discovery] board exposes all of the "UI"

(faders, buttons, indicators, display) to the host via a custom USB class.

Messages are serialized using [`postcard`](https://crates.io/crates/postcard).

On the host, a daemon is running which communicates to the hardware and keeps

track of PulseAudio state.  It has a configuration file for selecting which

channel controls which applications.  Streams are then attached to the mixer

channels automatically when they appear.

The firmware and host-side software are still in development - these features

are subject to change.

- New application streams are attached to channels based on a configurable

  property-matching table.  All streams connected to a channel will be forced

  to the volume reported by the fader.

- Main channel controls the currently selected default sink.

- Whenever a channel has an active stream, its reported icon will be displayed

  on the LCD.  For streams which do not properly report an icon, a second

  matching table can be used to select custom icons.

### Alternative Hardware

Right now, only the _Pavu Mixer_ hardware is supported.  As this board is not

commercially available, but a hardware mixer for PulseAudio could be

interesting for other people as well, I am open to extend the host-daemon to

support other boards as well.  For example, there are a lot of MIDI-based

digital audio mixers which would be a good candidate for support.  Please open

an issue on GitHub or contact me directly if interested.

## Project Structure

| Path | Contents |

| -- | -- |

| `Eyecandy/` | Pictures and "rendered" schematic ([`Pavu-Mixer-Schematic.pdf`](Eyecandy/Pavu-Mixer-Schematic.pdf)). |

| `Hardware/` | KiCAD project for the interface board & other hardware related files. |

| `hardware-tests/` | Test-firmware for demonstrating functionality of all parts of the hardware. |

| `common/` | Definitions shared between firmware and host-software (for [`postcard`](https://crates.io/crates/postcard) serdes). |

| `firmware/` | Firmware for the [STM32F3DISCOVERY][discovery] board. |

| `host-daemon/` | Host-side daemon for mixer communication and PulseAudio interaction. |

| `waveshare-display/` | Driver for the LCD screen (see its [README](waveshare-display/README.md) for details). |

## License

It is a difficult story... Individual parts of this project are licensed under

different terms:

- All files in the `Hardware/` directory (exception below) are licensed under

  the [CERN-OHL-W](LICENSE-HARDWARE).

- Files in `Hardware/3D` are licensed under [MIT](Hardware/3D/LICENSE-3D).

- The display driver in `waveshare-display/` is dual licensed under Apache 2/MIT

  as detailed in its own [README](waveshare-display/README.md).

- The remaining files of this project (including `common/`, `firmware/`,

  `hardware-tests/`, and `host-daemon/`) are licensed under the

  [GPL v3](LICENSE-SOFTWARE).

## Contribution

Unless you explicitly state otherwise, any contribution intentionally submitted

for inclusion in the work by you, as defined in the Apache-2.0 license, shall

be licensed as above, without any additional terms or conditions.