User:LordSputnik/Track System Redesign

From MusicBrainz Wiki

This page is a constantly evolving work in progress. It will never be finished! But hopefully it'll get to a point where the ideas are coherent enough to be implemented!

The aim of this wiki page is to present a comprehensive, clear and purposeful system to replace recordings.

Why Recordings are Bad

Consider this: A release is audio that you can buy or obtain in some format in some country. A work is an audio composition. A label is an organization which publishes audio. An artist is a person or group which creates audio. All MusicBrainz entities relate to something concrete and real. All except the Recording entity. A recording is defined as "representing distinct audio". It is an abstract, conceptual entity. This is why it should have no place in MusicBrainz.

What exactly is meant by "distinct audio"? This could refer to the audio created when a performance is recorded in a studio. It could just as easily refer to the audio on a CD track. Both interpretations are equally valid, but the Recording guidelines have nothing to say as to which interpretation is to be used. The recording level is a mixture of two more realistic levels - the mix and the master.

This proposal creates these two new entities, mix and master, to replace the recording with more meaningful levels. It also creates unique track entities which cannot be merged, to remove the need to deal with cases of "unique audio".

As Caller#6 put it:

"It seems clear that some people want to track the minutia of audio-quality data. That's awesome.

And it seems clear that some people don't. Some of us primarily want a place to store personnel-level metadata.

Why are we trying to do those two things in the same place?"


Works, mixes, masters and tracks can all be related to each other. A track can be related to all or none of the higher level entities. There should also be some way of lower level relationships overwriting higher level relationships. For example, both a track and a master are related to the same work. If an editor creates a relationship between the track and the master, the track's work relationship should somehow disappear and be replaced by the master's work relationship. In other words, a relationship on a higher-level entity should be inherited by a lower-level entity. Higher level entities can be related to multiple lower level entities, but lower level entities should generally only be related to one of each type of higher level entity.



A work is an artistic creation. It is the highest level entity of the four. Examples of a work include a song or some form of classical piece. Works are near enough perfect in their current form. They are well defined and already serve the intended purpose.


A mix is a version of a performance of a work. A mix can be made of a studio performance or a live performance. A mix does not refer to changes to the way the audio sounds. It refers to major, structural changes to the audio. For example, the removal of half of the song to create a radio edit, or the separating of instruments into two channels to create stereo audio.

Mixes can be merged, but this will hopefully happen less frequently than for recordings, due to the more objective nature of a mix. An editor must make an edit to associate a track with a mix, and this edit is subject to the voting process, like any other non-auto-edit.

If mixes are to have a length, then this should be set as the average length of all related tracks.

Performance ARs should be attached at the mix level. These relationships will need to be duplicated if parts of the performance feature on two separate mixes.


A master is a mix which has been edited or altered to change the sound, in preparation for the creation of a release. This entity isn't as common as the others mentioned here - relating a track to a master is optional, and should only be done where documented evidence supports the relationship being made. In general, this means that masters should correspond to the original master for a mix, or subsequent remasters of that original master.

Mastering ARs should nearly be attached at the master level, and not at the release level, with the possible exception of the "mastered by..." relationship itself, because that can sometimes apply to a specific format of a release (eg. vinyl mastering).

If masters are to have a length, then this should be set as the average length of all related tracks.


A track is the master after it has been copied onto a particular release. It is the lowest level entity of the four. It is unique to the single release it appears on, and lives and dies with that release. When a release is added, tracks are created, assigned MBIDs, and given titles. A mix could optionally be assigned to a track on release creation: we should have three options here: "Search for mix", "Add new mix", "Don't know" (leaves track with no mix relationship). The last two of these options could be batch applied to tracks.

The track names are displayed on the release main page. Clicking a track name will take the editor to the track.

In an ideal system, AcoustIDs should be related only to tracks. However, this is a matter for luks to decide on, and until he's reviewed any change to the MusicBrainz schema and decided on a course of action, MusicBrainz should stop displaying AcoustIDs on any entity. With no changes to AcoustID, the links in the AcoustID database would still point to recordings, now redefined as mixes.


  1. Create a track entity. Replace all tracks in the db with this new entity, and relate them to recordings attached to releases through the current system.
  2. Create the master entity, and master-* relationship types.
  3. Rename recording entity to mix. Update style guidelines to explain the migration process and the new roles of the entities.
  4. Create a few wizards/scripts to help with moving mastering relationships from mixes to masters, and to move them from releases to masters.
  5. Get editors to redo all the relationships!