sessionmixer

A lightweight, configurable desktop mixer for controlling cue mixes and audio routing on audio interfaces with onboard mixing.

Demo

sessionmixer controlling a Focusrite Scarlett interface with real-time level metering

Overview

sessionmixer provides an ergonomic control surface for audio interfaces that include onboard DSP mixing capabilities. Instead of navigating complex manufacturer software, sessionmixer lets you create a streamlined, personalized mixer layout with just the controls you need.

Whether you're managing monitor mixes in a recording session, routing audio for a podcast, or controlling a live streaming setup, sessionmixer gives you quick access to the controls that matter most.

Supported Hardware

• Focusrite Scarlett (4th generation) - Tested with 16i16 and 18i20
• Additional interface support planned for future releases

Features

• Ganged Faders - Control multiple hardware channels with a single fader (e.g., stereo pairs)
• Configurable Tapers - Choose between logarithmic (dB) or linear fader response
• Level Metering - Real-time signal levels displayed as color-coded fader backgrounds
• Bidirectional Sync - Changes made externally (other software, hardware controls) are reflected in the UI
• YAML Configuration - Simple, human-readable configuration files

Requirements

• Linux with ALSA
• Go 1.21+ (for building from source)
• A supported audio interface

Dependencies

sessionmixer uses scarlettctl to communicate with Focusrite interfaces and dfx for the user interface.

Installation

# Clone the repository
git clone https://github.com/michaelquigley/sessionmixer.git
cd sessionmixer

# Build
go build ./cmd/sessionmixer

# Install (optional)
sudo cp sessionmixer /usr/local/bin/

Configuration

sessionmixer uses a YAML configuration file located at:

~/.config/sessionmixer/session.yaml

Example Configuration

# ALSA card number (use `aplay -l` to find your device)
card: 1

# Define your faders
gang_controls:
  # A single-channel fader
  - name: "Mains"
    controls:
      - "Analogue 1 Playback Volume"
    unit: "db"
    taper_db: 72

  # A stereo gang with level metering
  - name: "Headphones"
    controls:
      - "Mix A Input 01 Playback Volume"
      - "Mix A Input 02 Playback Volume"
    levels:
      - "pcm:0.0/Level Meter[15]"
      - "pcm:0.0/Level Meter[16]"
    unit: "db"
    taper_db: 72

Configuration Reference

Field	Description
card	ALSA card number for your interface
gang_controls	List of fader definitions
name	Display label for the fader
controls	ALSA control names to gang together
unit	Display format: "db" or "raw"
taper_db	dB range for logarithmic taper (omit for linear)
levels	Optional: level meter controls for signal display

Finding Control Names

Use scarlettctl to discover available controls on your interface:

scarlettctl list

Usage

# Run the mixer
./sessionmixer run

# With verbose logging
./sessionmixer run -v

Controls

• Drag faders to adjust levels
• Fader values sync bidirectionally with hardware
• Level meters (when configured) show real-time signal levels:
  • Green = normal levels
  • Yellow = approaching peak
  • Red = high levels

License

MIT