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rmpd — music player daemon

CI Security Audit License

rmpd is a modern, high-performance, memory-safe music server written in pure Rust. It aims for 100% compatibility with the Music Player Daemon (MPD) protocol while providing first-class extensibility through a plugin architecture.

Features

  • 🎵 MPD Protocol Compatible - Works with existing MPD clients (ncmpcpp, mpc, Cantata)
  • 🦀 Pure Rust - Memory-safe, fast, and reliable
  • 🔌 Extensible - Plugin system for decoders, outputs, and inputs
  • 🎧 High-Quality Audio - DSD support, ReplayGain, gapless playback, crossfade
  • 🎼 Format Support - FLAC, MP3, Ogg Vorbis, WAV, AAC, DSD (DoP and native)
  • 🏠 Multi-Room - Plays to all enabled outputs at once; stream over HTTP (httpd output) or feed an external Snapcast server via FIFO
  • 🖥️ Desktop Integration - Native MPRIS D-Bus interface (media keys, playerctl, GNOME/KDE) plus mDNS auto-discovery
  • 🌐 Remote Libraries - Browse and stream from OpenSubsonic servers (Navidrome, Airsonic, gonic) as a music source, built behind the subsonic Cargo feature
  • ⚡ Efficient - Runs on everything from Raspberry Pi to high-end servers

Architecture

rmpd/
├── rmpd/               # Main binary
├── rmpd-core/          # Core types and traits
├── rmpd-protocol/      # MPD protocol implementation
├── rmpd-player/        # Audio playback engine
├── rmpd-library/       # Music library/database
├── rmpd-plugin/        # Plugin system
└── rmpd-stream/        # Streaming support

Quick Start

Prerequisites

System dependencies:

# Ubuntu/Debian
sudo apt-get install libasound2-dev pkg-config

# macOS
brew install pkg-config

Build

cargo build --release

Run

./target/release/rmpd --bind 127.0.0.1 --port 6600 --music-dir ~/Music

Test with mpc

# Check status
mpc status

# Update library
mpc update

# Add and play music
mpc add /
mpc play

# Play internet radio (any HTTP/HTTPS stream URL)
mpc add https://stream.example/radio.mp3
mpc play
mpc current   # shows the live ICY "now playing" title for streams

Configuration

rmpd does not require you to create a config file. On first start, if no config file is found, rmpd writes a commented starter config to ~/.config/rmpd/rmpd.toml and logs the path it chose. You can also manage this explicitly:

  • --generate-config writes the starter config on demand and refuses to overwrite an existing file.
  • --print-config-path prints the path that would be used, without writing anything.
  • --no-config skips file discovery entirely and runs on built-in defaults.

Search order

When --config is not given, rmpd searches these locations in order and uses the first one that exists:

  1. the path given to --config
  2. $XDG_CONFIG_HOME/rmpd/rmpd.toml (usually ~/.config/rmpd/rmpd.toml)
  3. ~/.rmpd.toml
  4. ~/.rmpd/rmpd.toml
  5. /etc/rmpd/rmpd.toml

This mirrors MPD's own search order ($XDG_CONFIG_HOME/mpd/mpd.conf, ~/.mpdconf, ~/.mpd/mpd.conf, /etc/mpd.conf).

Every section and key is optional — anything omitted uses a built-in default, so a partial config is valid. Paths beginning with ~ are expanded.

A minimal config:

[general]
music_directory = "~/Music"
log_level = "info"

[network]
bind_address = "127.0.0.1"
port = 6600

[audio]
default_output = "alsa"
replay_gain = "auto"

See rmpd.toml for a complete, annotated configuration example.

Diagnostics

Unrecognized keys are reported at startup instead of being silently ignored, with a suggestion when a typo is likely, for example:

unknown config key `general.msic_directory` (did you mean `music_directory`?)

Keys carried over from mpd.conf produce a migration hint pointing at the rmpd equivalent. Unknown keys only warn — they never stop the daemon. An explicitly passed --config file that cannot be read or parsed is fatal, since a config you asked for by name should never be silently substituted with defaults.

A missing or nonexistent music_directory is not fatal: rmpd warns, starts anyway, and skips library scanning, matching MPD's degrade-don't-die behaviour.

log_level under [general] controls logging (trace/debug/info/ warn/error). --verbose forces debug, and the RUST_LOG environment variable overrides both.

The following keys were parsed in older versions but never did anything and have been removed; a config that still sets them gets a startup warning naming each one:

  • audio.gapless — gapless playback is always on
  • the entire [decoder] section, including decoder.enabled — decoders come from a compile-time registry
  • database.cache_size
  • database.fts_enabled

Music Sources (OpenSubsonic)

rmpd can aggregate a remote OpenSubsonic server (Navidrome, Airsonic, gonic, …) into its library as a music source. The remote catalog is synced into the database at startup and on update, and tracks stream on demand through the same HTTP path used for internet radio — so any MPD client browses and plays them like local files (under mount-style paths such as home/Artist/Album/<id>.flac, where the source name is the mount point).

Build with the subsonic feature, then add one or more [[source]] blocks:

cargo build --release --features subsonic
[[source]]
name = "home"                      # becomes the mount point (top-level directory)
type = "subsonic"
enabled = true
url = "https://music.example.com"
username = "alice"
password = "secret"                # or use `api_key = "..."` instead
# max_bitrate = 320                 # optional server-side transcode cap (kbps)
# format = "mp3"                    # optional transcode target ("raw" = no transcode)

Credentials are never written to logs. An unreachable server is skipped at startup without aborting (previously-synced tracks remain browsable).

Desktop Integration (MPRIS)

rmpd exposes a native MPRIS interface on the session D-Bus as org.mpris.MediaPlayer2.rmpd. This lets Linux desktops (GNOME Shell, KDE Plasma), playerctl, lock screens, and multimedia keys discover and control rmpd directly — no external bridge such as mpDris2 required.

It is enabled by default and can be toggled with mpris under [network]. Verify it with:

playerctl -p rmpd metadata
busctl --user introspect org.mpris.MediaPlayer2.rmpd /org/mpris/MediaPlayer2

rmpd also advertises itself over mDNS/Zeroconf so MPD clients on the local network can auto-discover the server.

Audio Format Support

Supported Formats

  • Lossless: FLAC, WAV, ALAC, APE, WavPack, TrueAudio
  • Lossy: MP3, Ogg Vorbis, Opus, AAC, MP4
  • High-Resolution: DSD (DSF, DFF) with DoP and native playback
  • Streaming: HTTP streams, Icecast, internet radio

DSD Support

rmpd includes comprehensive DSD support:

  • DSD64, DSD128, DSD256 and higher sample rates
  • DoP (DSD over PCM) for wider DAC compatibility
  • Native DSD playback for compatible hardware
  • Automatic format detection and conversion
  • DSD-to-PCM fallback decodes to a 44.1 kHz-family rate and resamples to the output device's native rate using the configured resampler_quality, so a sound server (e.g. PipeWire) never resamples internally — avoiding underruns and keeping DSD's ultrasonic noise out of the audible band

Development

Running Tests

cargo test --workspace --all-features

Linting

# Format code
cargo fmt

# Run clippy
cargo clippy --workspace --all-targets --all-features

CI/CD

This project uses GitHub Actions for CI/CD with:

  • Multi-platform testing (Ubuntu, macOS)
  • Multi-architecture builds (x86_64, ARM64)
  • Strict linting with Clippy
  • Security audits with cargo-audit and cargo-deny
  • Code coverage reporting
  • Automated dependency updates via Renovate

See CI.md for detailed CI/CD documentation.

Current Status

Implemented ✅

  • Core Infrastructure

    • MPD protocol server (TCP/Unix sockets)
    • Event bus system
    • Configuration management
    • Logging with tracing

  • Audio Playback

    • Multi-format decoding (FLAC, MP3, Vorbis, WAV, AAC, DSD)
    • High-rate DSD support (DSD128, DSD256+)
    • Multiple output types (ALSA, PulseAudio, PipeWire)
    • Gapless playback
    • Crossfade and MixRamp transitions
    • ReplayGain support
    • Internet radio: HTTP(S) streaming input with Shoutcast/Icecast (ICY) "now playing" metadata
    • httpd output streams to browsers (HTTP/1.0) and to Shoutcast/Icecast clients (ICY 200 OK greeting + interleaved ICY StreamTitle metadata)

  • Library Management

    • Filesystem scanning
    • SQLite database
    • Metadata extraction with lofty
    • Full-text search with tantivy
    • Album art support

  • MPD Protocol

    • Core playback commands (play, pause, stop, seek)
    • Queue management (add, delete, move, shuffle)
    • Database queries (find, search, list)
    • Status and statistics
    • Playlist management (.m3u, .pls, XSPF/ASX; .cue sheets expand into range-restricted virtual tracks)
    • Output control

  • Desktop Integration

    • Native MPRIS D-Bus interface (org.mpris.MediaPlayer2.rmpd)
    • Media keys, playerctl, and GNOME/KDE media controls
    • mDNS/Zeroconf service advertisement for client auto-discovery

  • Remote Libraries

    • OpenSubsonic music sources (Navidrome, Airsonic, gonic) via the subsonic Cargo feature

In Progress 🚧

  • Compressed stream encoders (FLAC / Opus / Vorbis) for the httpd output
  • Network storage backends (SMB / NFS)

Compatibility

Tested MPD Clients

  • ✅ mpc - Command-line client
  • ✅ ncmpcpp - TUI client
  • ✅ Cantata - Qt GUI client
  • ✅ rmpc - Modern TUI client
  • 🚧 MPDroid - Android client (testing in progress)
  • 🚧 MPDluxe - iOS client (testing in progress)

Multi-Room Audio

rmpd plays to all enabled outputs simultaneously, so local audio and a network stream can run at once. Two routes to networked/multi-room playback:

  • HTTP streaming — enable a type = "httpd" output (default port 8000) and point any browser, phone, or another MPD/VLC at http://<host>:8000. Works today, no extra daemon required (encoder = "wav" or "pcm").
  • Snapcast (synchronized) — enable a type = "fifo" output writing to /tmp/snapfifo and run an external Snapcast snapserver reading that FIFO for sample-accurate multi-room sync.

Performance

rmpd is designed for efficiency:

  • Startup time: < 500ms with 100k song library
  • Memory usage: < 20MB idle, < 150MB with 100k songs loaded
  • CPU usage: < 5% during FLAC playback
  • MSRV: Rust 1.75.0+

Project Goals

  1. 100% MPD Compatibility - Drop-in replacement for MPD
  2. Modern Architecture - Clean, modular, testable code
  3. Extensibility - Plugin system for community contributions
  4. Performance - Efficient resource usage
  5. Multi-Protocol - MPD, OpenSubsonic support

Contributing

Contributions are welcome! Please:

  1. Fork the repository
  2. Create a feature branch
  3. Make your changes with tests
  4. Run cargo fmt and cargo clippy
  5. Submit a pull request

See CI.md for development guidelines and CI/CD information.

License

Licensed under either of:

at your option.

Acknowledgments

Links

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Modern, high-performance MPD (Music Player Daemon) server written in pure Rust with DSD support, multi-room audio, and extensible plugin architecture

Topics

audioaudiophiledsdmpdmulti-room-audiomusic-playermusic-serverrustsnapcast

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