A woman using the card catalog at the main reading room of the Library of Congress (circa 1940).

Classical Music Metadata Without Tags

Baoshan Sheng
Tonal
Published in
6 min readJul 12, 2023

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Don’t embed music metadata in audio files, and here is why.

Audio files are full of music tags. The original intention was to make them accessible. These tags have been serving the purpose for decades. But this is inelegant. The proofs are in the long, ugly toolchain and workflow:

  • keep local tags up to date with upstream sources like MusicBrainz
  • sync audio filenames with tags
  • edit tags (maybe in batch with scripts) and write back to the audio files (maybe on NAS or cloud-based storage)

What have we finally got? Disconnected islands of redundant and stale information.

Tags Are Dead

Embedded tags are retiring in one way or another: when you watch Apple TV+, you won’t see them; when you listen to Apple Music, you won’t see them; when you browse your local video or music collection in Plex or Roon, there is a big chance you won’t see them.

  • Hosting the same song dozens of times with the language of tags being the only difference is a waste for streaming services. It also harms the user experience — updates to metadata take more steps to propagate.
  • For modern apps like Plex or Roon, their envisioned experience relies on data sources such as TiVo or The Movie Database. They won’t even increase their “surface area” by adding features like tag editing.

Without any embedded tags, audio files become immutable automatically and are suitable for content-addressable storage. Also, the artwork will not be duplicated in every single track. But how about the music metadata? Let’s have some music first.

Ein deutsches Requiem is a choral work composed by Johannes Brahms between 1865 and 1868. It is scored for a soprano, a baritone, a mixed choir, and an orchestra.

Apple Music presenting Brahms’s Ein deutsches Requiem.

How many tags do you need for the 7 tracks? The first track alone needs 9 tags (that’s not counting album-level tags such as album title, genre, artwork, etc.):

9 tags are required for the first track.

To describe all 7 tracks, you need 59 tags. And you have to be extremely careful not to mess up with the ordering of artists like Apple Music did:

Inconsistencies in the ordering of artists found in Apple Music.

Long-Live the Music Metadata

Don’t store music metadata in an opaque format like binary. XML is much better but still not good enough. Simple plain text is the best.

For this album, 59 tags can be reduced to 17 lines — no more redundancy, no need to check over and over, and roles like baritone and soprano are also included:

17 lines are enough to model the Ein deutsches Requiem album.

Tonal Metadata Language

The example text is written in Tonal Metadata Language and is edited in the web-based Tonal Editor. The language is designed for accuracy, brevity, and clarity. The full specifications are defined in the user guide of Tonal.

Take another album as an example:

An album rendered in the new Tonal app.

The corresponding metadata document is presented below — very intuitive because it pays homage to physical albums’ back covers.

Separation of Concern

With the new Tonal app, music metadata is no longer embedded in audio files — you can modify the music metadata anytime without touching the audio files. Save the document in Safari; updates will be pushed to the Tonal app in real time — you will never see stale music metadata again.

Updates to music metadata will be pushed to the app in real time.

A New Era of Music Metadata

From audio players to music streaming apps, music metadata drives music content consumption silently — to some extent, music metadata is the content.

The new Tonal app is designed to prove it is time for a new music metadata database that is simple, open, designed for collaboration, and supports classical music well.

Before You Start

Tonal is a misfit in many waysit does not fit everyone’s needs, and for those who choose Tonal, Tonal won’t be their only player:

  • Due to the always-bit-accurate strategy, you can neither listen to 192 kHz albums on your Mac’s built-in speakers nor play a DSD album on a PCM-only D/A converter.
  • Tonal collects albums into its managed directory, which contains packed lossless audio data in a uniform encoding (but no music metadata). If you cannot make a standalone space for Tonal, whether internal or external, on a NAS or an SD card, there may be a better time for you to experience Tonal.
By 2030, a $50 SSD can store over 30,000 CD-quality albums. Source: Wikibon
  • Tonal accepts lossless and complete discs only. CD-quality discs must also be AccurateRip verified (Tonal uses CUETools to repair broken rips automatically).

You can download Tonal for free from the Mac App Store if such limitations are acceptable. At only 25 MB, Tonal is lightweight. The free version has no restrictions on features or usage. You can add up to 20 (CD-quality or high-res) discs to build a mini collection of your favorite artists.

A one-time (non-subscription) in-app purchase, priced at $99.99 for the introductory period, is offered to remove the limit. There is an even better way to unlock — if you have reviewed Tonal, please contact me for a free coupon; if you have conducted an in-depth review, an additional coupon will be provided to share with your best friend.

Please read the complete User’s Guide before downloading.

Listen Different

A homage to Apple’s “Think Different” slogan.

This article introduces how Tonal invented a metadata language and an editor to separate music metadata from audio files. This may not be the most interesting one in the series of articles on Tonal:

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Baoshan Sheng
Tonal

Founder of International Classical Music Database