meta-sonata

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Automatically fetch and fill missing music metadata, cover art, and synced lyrics for your music folders. Preview the changes, then apply them with one command.

Two Commands

Query and preview the metadata meta-sonata finds. Nothing is written:

meta-sonata enrich "/music/album"

Fetch and write metadata, cover art, and lyrics in one step:

meta-sonata enrich "/music/album" --write

Both commands accept an album folder or a larger music directory. Existing tags, filenames, and folder structure are trusted first; online sources fill the gaps.

Why meta-sonata?

• Local first: existing tags, folder names, and track structure anchor the match.
• Conservative: track count, duration, live/studio, and ambiguity checks prevent risky writes.
• Complete: metadata, cover art, and synced lyrics in one command.
• Automation-ready: dry runs, external incremental state, recursive discovery, and JSON audit plans.

Quick Start

pipx install meta-sonata

Or install it with uv:

uv tool install meta-sonata

macOS App

The macOS app has two modes. Single Track accepts a dropped audio file, completes its metadata, and lets you drag the output copy into Finder. Library opens a local folder in the app's read-only metadata browser. Its helper service binds only to a random local port, with no separate web installation required. The original files are never modified.

The app follows the macOS language by default and can be changed from its language menu. It supports English, Simplified Chinese, Traditional Chinese, Japanese, Korean, French, German, Spanish, and Brazilian Portuguese.

Build the Apple silicon .app and .dmg locally with:

./scripts/build_macos_release.sh

The default build is ad-hoc signed for local validation. Set MACOS_SIGN_IDENTITY to a Developer ID identity and notarize it before public distribution.

Typical output:

scan: root=/music/album files=12 album_groups=1 loose_tracks=0 max_depth=3
resolve: 1/1 /music/album
lyrics: 1/1 /music/album
dry run: 1 plan(s)
- album: Artist / Album: artist=Artist  album=Album  year=2006  tracks=12  confidence=0.96  lyrics=11/12
nothing written; pass --write to apply

enrich enables metadata lookup, cover lookup, and lyrics by default. It scans up to three directory levels; use --max-depth N or --recursive when needed.

What It Can Fill

Album metadata sources: MusicBrainz, iTunes, and NetEase.

Lyric sources: QQ Music, NetEase, KuGou, KuWo, and Migu.

meta-sonata sources

Put It in a Pipeline

Run it after download/extraction/CUE splitting and before the final library sync:

meta-sonata enrich "/staging/new-music" \
  --changed-only \
  --state-dir "/var/lib/meta-sonata" \
  --write

Incremental state stays outside music folders. No marker files are added to albums.

Optional Metadata Browser

meta-sonata web "/music" --host 127.0.0.1 --port 8765

Open http://127.0.0.1:8765/ to browse audio files, core tags, source IDs, technical details, covers, and embedded lyrics. The web UI has no write endpoints.

Shown with CC-licensed audio and artwork from Nine Inch Nails' The Slip. See the asset attribution.

Local data storage

Embedded file tags remain the portable source of truth. The macOS app builds a rebuildable local catalog in the background for cross-folder lookup, match history, and future confirmation workflows. Third-party responses live in a separate disposable cache:

• Durable catalog: ~/Library/Application Support/com.sendinge.meta-sonata/catalog.sqlite3
• API cache: ~/Library/Caches/com.sendinge.meta-sonata/provider-cache.sqlite3

Deleting the API cache does not affect music or catalog data. Catalog failures also never block browsing or enrichment. Real MusicBrainz network requests are limited to one per second across CLI, macOS, and test code paths. Every third-party failure degrades to a warning while local processing and other providers continue.

Safety

• Every write command is a dry run unless --write is present.
• Low-confidence lyrics and ambiguous release identities are skipped.
• Mixed loose tracks are not forced into a fake album.
• Real libraries can be protected with META_SONATA_PROTECTED_PATHS.
• Tests generate silent FLAC files; no copyrighted media is committed.

More

• Detailed guide
• Changelog
• Public test-fixture policy
• MIT License

Python 3.9+ is supported. The project is currently an early 0.2.x release; unofficial provider endpoints may change or be rate-limited.