|Status: This is proposed style for a recently released feature (24 May 2009), currently under development. It is not yet official.|
A Release Group is a MusicBrainz concept introduced in May 2009 used to group several different releases into a single logical entity. Every release belongs to one, and only one release group.
Both release groups and releases are "albums" in a general sense, but with a slight difference: a release is something you can buy as media, e.g. a CD, a vinyl record etc. on its own, while a release group embraces the concept of an album -- it doesn't matter how many CDs or editions/versions it had. When an artist tells you "We've released our new album", they're talking about a release group. When his publisher says "This new album gets released next week in Japan and next month in Europe", they're talking about the different releases that belong in the release group that the artist told you about.
MusicBrainz automatically considers every release in the database to be part of a release group, even if this group only contains the one release. As an editor you don't have to worry about creating release groups, you will only need to merge existing ones.
There are a number of situations in which merging releases groups is appropriate. All of the following can be part of a single release group:
- Regular releases
- Since every release is inside a release group, some release groups have only a single release.
- International release variations
- Releases are often released with different tracklists in different markets, some may even have additional bonus discs. Due to WhatDefinesAUniqueRelease these would be separate releases at MusicBrainz, but should be merged together into the same release group.
- Deluxe/limited editions and reissues/remasters
- Just like above, a "special" edition of an album, a reissue of an album, or a remaster, should all be part of the same release group.
- Promotional and pirated versions
- Promotional and pirated versions of albums, singles etc should be in the same release group as the regular official release.
- Multi-disc releases
- Each disc in a multi-disc release at MusicBrainz is a separate release (named according to disc number style), but all discs should be part of the same release group.
- Box sets
- A special case of the above; each disc in a box set would normally be part of the same release group.
- Transliterated or translated pseudo-releases should be part of the same release group as the official release.
- Transplant's single "Diamonds and Guns" is a single release inside its own group.
- Weezer's "Weezer (Red Album)" has ten editions in the database, some releases from different countries, some deluxe editions, and one transliteration.
- Franz Ferdinand's "Tonight: Franz Ferdinand" was issued on its own, with a bonus disc, and on two vinyl records.
- A 3 disc self-titled compilation by "Nirvana".
- Mozart's 9 volume, 170 disc "Wolfgang Amadeus Mozart: Complete Works" box set, or Enya's 3 disc box set "A Box of Dreams".
- Blind Guardian's "Nightfall in Middle-Earth" was first released in 1998 and then remastered with a bonus track in 2007
- The musical "My Fair Lady" (Original London Cast) was originally released on vinyl in 1959 and on CD in 1998.
When Not to Group Releases together
There are a number of cases where it is not appropriate for releases to be part of the same group:
- A Series of different volumes that may have been released over time. Typical examples are "Café del Mar", "Hitzone", "Ministry of Sound" and "Now That's What I Call Music!". Each volume's discs belong in a release group though, e.g. "Volume 1" and "Volume 2" of the Trance Voices series.
- Different bootleg recordings of a live show, e.g. bootleg 1 and bootleg 2 of a 1970 Pink Floyd concert in San Francisco.
- For Box Sets or Multi-Disc Releases where each disc has been released separately. If these individual discs have not been duplicated due to the rules outlined at "What Defines A Unique Release", they should not be grouped together as per the normal box set rules noted above.
- "2 in 1" releases should have a third release group. This applies to all Release Types, including 2-in-1 albums and double A-side singles. e.g. ABBA's "Waterloo / Voulez-Vous" should not be merged into "Waterloo" or "Voulez-Vous".
Use of Attributes
The title of a release group should usually be the title of its individual releases, removing Extra Title Information added due to Disc Number Style, Volume Number Style etc. In the case of re-releases with different titles, the principle of Consistent Original Data should be applied to choose the release group's title from one of the linked releases.
The types of a release group are the same as those possible for Release Type and should normally be the same as all of the releases in that group. This may not always be the case. It is OK for a bonus disc EP, remix, live disc etc to be inside the same "Album" release group as the accompanying album disc.