MobMusic

Transcodes a music library to lossy formats for portable devices. Syncs Jellyfin playlists as M3U files. Auto-triggers when a registered USB drive is plugged into a headless Debian server.

How it works

Music library ──> transcode (aac/opus/mp3) ──> USB drive
Jellyfin playlists ──> M3U files with rewritten paths ──> USB drive

Source library can contain FLAC, ALAC, APE, WAV, MP3, AAC, OGG, WMA, or Opus files — all are transcoded to the target codec.

Register a USB device once with setup. After that, plugging it in triggers a full sync automatically via udev + systemd: mount, transcode new/changed files (mtime-based — re-transcodes when source is updated), sync playlists, clean orphans, unmount, email notification.

Source library structure is Artist/Album/tracks. Album directories can use any of these year formats: Album (1965), Album [1965], 1965 - Album, [1965] Album, Album - 1965, or no year at all. Artists prefixed with "The" (e.g., The Beatles) are automatically normalized to Beatles, The in the target.

Requirements

• Locally mounted music library (any format ffmpeg can decode)
• Python 3.13+ with ffmpeg-python
• FFmpeg with libfdk_aac (falls back to built-in aac if unavailable)
• Jellyfin server (for playlist sync)
• Linux with udev + systemd (for auto-sync)

Installation

The systemd service file assumes the repo lives at /opt/mobmusic. Clone there and set up the venv:

sudo mkdir -p /opt/mobmusic
sudo chown $(whoami) /opt/mobmusic
git clone https://github.com/kontell/mobmusic.git /opt/mobmusic
cd /opt/mobmusic
python3 -m venv venv
venv/bin/pip install ffmpeg-python

Usage

# Register a USB device interactively
./mobmusic.py setup

# Manual sync
./mobmusic.py sync /path/to/target --codec opus --bitrate 90k

# Dry run
./mobmusic.py sync /path/to/target --dry-run

# Sync playlists only
./mobmusic.py playlists /path/to/target --user conor

# Watch auto-sync logs
journalctl -t mobmusic -f

Configuration

Server (creds.conf): Jellyfin URL/API key, SMTP credentials, default source path and FFmpeg location. Copy the template and fill in your values:

cp creds.conf.example creds.conf
chmod 600 creds.conf
# Edit creds.conf with your settings

Per-device (.mobmusic.conf on USB root): Jellyfin user, email, codec, bitrate, directory structure. Written by setup, travels with the device.

Codecs

Option	Encoder	Extension
aac	libfdk_aac	.m4a
opus	libopus	.opus
mp3	libmp3lame	.mp3

Directory structures

• initial — A/Artist Name/2024 - Album Title/track.m4a
• mirror — preserves source layout as-is

System integration

The setup command writes udev rules and guides you through symlinking the systemd service and polkit rule. After first-time setup:

sudo ln -sf /opt/mobmusic/99-mobmusic.rules /etc/udev/rules.d/
sudo ln -sf /opt/mobmusic/mobmusic-sync@.service /etc/systemd/system/
sudo cp /opt/mobmusic/10-mobmusic-mount.rules /etc/polkit-1/rules.d/
sudo udevadm control --reload-rules
sudo systemctl daemon-reload