FxLinux

A from-scratch Linux audio enhancer inspired by FxSound (Windows-only) — built on PipeWire and open-source LV2 plugins, not a port or decompilation of FxSound's binary. A simple GTK4 control panel (a few sliders + genre presets) sits on top of a tuned multi-stage DSP chain that runs as a PipeWire virtual sink, so any application's audio gets processed system-wide.

Features

• Live DSP chain, tuned by ear stage by stage:
  • Harmonic bass enhancer and exciter (Calf) for fuller low end and clearer highs
  • Stereo widening + ambience (Calf Stereo Tools + Reverb)
  • Adaptive bass leveling — a multiband compressor gently reins in already-hot bass automatically, so you don't have to retune the Bass slider per track
  • 8-band parametric EQ (LSP), driving each preset's actual frequency-response curve
  • True-peak-safe limiter (LSP) with headroom margin, so nothing clips regardless of how far the sliders are pushed
• 5 presets, each with its own EQ curve, not just slider values:

  Preset	Character
  Flat / Reference	Minimal processing, just the safety limiter — baseline for A/B
  Music	Warm bass, gentle treble lift, moderate width
  Movie	Dialogue-presence boost, stronger bass, wider ambience
  Voice / Podcast	Rumble/proximity cut, articulation boost, dry
  Gaming	Footstep/cue clarity, wide ambience for positional feel

• Live control — dragging a slider or switching presets updates the running audio engine instantly, no restart or audio interruption
• Auto-reconnect — if the audio engine restarts for any reason, the control panel detects it and automatically re-applies your last-selected preset
• Self-installing — one script sets up system packages, builds, and wires everything into PipeWire + your login session

How it works

The DSP chain runs inside PipeWire's own filter-chain daemon (a small process PipeWire ships specifically for this), loading Calf and LSP LV2 plugins per data/filter-chain/99-fxlinux.conf. This creates a virtual sink named FxLinux that any app's audio can be routed through. The GTK4 app (crates/fxlinux-app) is a separate control panel: it talks to the already-running audio engine over PipeWire's native protocol, live-updating plugin parameters — it does not host any audio processing itself.

Requirements

• Ubuntu or another apt-based distro running PipeWire (not PulseAudio-only — check with pactl info | grep -i pipewire or wpctl status)
• sudo access, for one-time package installation

Installation

./install.sh

This installs the required system packages (build tools, GTK4/libadwaita, PipeWire dev headers, the Calf and LSP plugin sets), installs Rust via rustup if not already present, builds FxLinux in release mode, and runs fxlinux-app install to:

• write the DSP chain config to ~/.config/pipewire/filter-chain.conf.d/99-fxlinux.conf (skipped if one already exists, so it won't clobber any hand-tuning)
• enable and start filter-chain.service
• add an autostart entry so the control panel launches at login

Safe to re-run at any time.

After installing

Set FxLinux as your default audio output — GNOME Sound Settings, or:

wpctl status                 # find FxLinux's sink id under "Filters"
wpctl set-default <id>

Then launch the control panel (or just log back in — it autostarts from then on):

./target/release/fxlinux-app

Usage

• The preset dropdown picks a full tuned sound (EQ curve + slider positions) in one go.
• The four sliders — Bass Boost, Fidelity, Ambience, Output — fine-tune on top of whatever preset is selected, live.
• If the banner "Audio engine not connected" appears, filter-chain.service isn't running — check systemctl --user status filter-chain.service.

Project structure

fxlinux/
  install.sh                              # bootstrap: packages, Rust, build, install
  data/filter-chain/99-fxlinux.conf       # the tuned DSP chain (source of truth for the installer)
  crates/fxlinux-app/
    src/main.rs                           # entry point + `install` subcommand
    src/install.rs                        # writes config/service/autostart
    src/audio/controls.rs                 # slider -> plugin control mapping
    src/audio/pw_worker.rs                # PipeWire connection, live control, reconnect handling
    src/presets/model.rs                  # preset schema + the 5 factory presets
    src/presets/store.rs                  # JSON persistence under ~/.config/fxlinux/presets/
    src/ui/window.rs                      # GTK4 + libadwaita UI
    examples/set_control.rs               # debug CLI: poke one control live from the terminal

Development

cargo build                                          # debug build
cargo run --example set_control -- bass:amount 3.0   # poke a live control directly, for debugging

Presets are plain JSON under ~/.config/fxlinux/presets/ (seeded from the factory set on first run) — hand-edit or add files there to experiment with your own.