Multi-value Plugin

Multi-values on a tag is useful to provide different and independent information belonging to the same context.

This plugin provides a boosted modify command to also add/remove values in multi-value tag. It can also fix grouping field and add work field.

Installation

pip install beets-multivalue

Pypi: https://pypi.org/project/beets-multivalue

Beet official list tags

A few fields already support native multi-values separated with \␀. Those are always available in the command without a configuration change. The current fields are:

• artists
• albumartists
• artists_sort
• artists_credit
• albumartists_sort
• albumartists_credit
• mb_artistids
• mb_albumartistids

String multi-value tags

Some fields do not support multi-values yet like genre or some may never support it as not a "standard" like grouping.

An example could be to add multiple genres separated by a comma: Rock,Hard Rock

Some external tools also supports custom separator splitting like navidrome since v0.55.0.

By default, no field is considered a string multi-value. Each one must be explicitly defined in the configuration with the expected separator:

multivalue:
  string_fields:
    grouping: ";"
    genre: ","

Multi Modify Command

Usage

# Initial: genre: Rock

# Add a value
beet multimodify grouping+="Hard Rock" <query>
# genre: Rock,Hard Rock

# Add and remove values
beet mmod genre+="Classic Rock" genre-="Hard Rock" <query>
# genre: Rock,Classic Rock

# Original modify command still applies
beet mmod genre+="Classic Rock" genre-="Hard Rock" year! title="Best song"

# Adding the same value is detected and avoided. By default, exact match is applied.
# It is easy to remember, there is the "=", the same used in a regular query.
# Initial: genre: Rock
beet multimodify grouping+="Rock" <query>
# genre: Rock

# For case insensitivity, add "~" as in a regular query.
beet multimodify grouping+=~rock <query>
# genre: Rock

# It is also possible to use the ones from a plugin by adding the equivalent prefix.
# For example with bareasc set to the prefix "#".
# Initial: artists: [Eric]
beet multimodify artists+=#Éric <query>
# no change

# The same work for removing

# Initial: genre: Rock
beet multimodify grouping-="Blues" <query>
# No change

# For case insensitivity, add "~" as in a regular query
# Initial: genre: Rock
beet multimodify grouping-=~rock <query>
# genre: ""

# For bareasc set to the prefix "#"
# Initial: artists: [Éric]
beet multimodify artists-=#Eric <query>
# artists: []

# Removing is also supporting Regex
# Initial: artists: [Eric]
beet multimodify artists-=:E?ic <query>
# artists: []

# Adding can not support regex as else the regex itself would be added. 
# If you want to harmonize the data, you may remove and add at the same time.
# Initial: genre: Rock&Roll
beet multimodify 'genre-=:Rock.+' genre+=Rock <query>
# genre: Rock

# Order of execution
# genre: original
beet mm genre+=base genre-=base genre=base,pivot
# genre: pivot,base

# Deletion always win
beet mm genre! genre+=base genre-=base genre=base,pivot
# genre:

# Reset field first
beet mm  genre= genre+=new genre-=new2
# genre: new,new2

The command is influenced by the modify one and provides the same flags. By default, a confirmation after showing the diff is requested and highly recommended to avoid any data loss.

Order of execution

1. Direct assignment are always run first: genre=Rock. If multiple assignments on the same field are written, the last one win.

2. Values are removed: genre-=Rock. It allows to do some pre-cleaning before adding values in the same run. Always with capital R: genre-=rock genre+=Rock. Values are removed in order from the CLI genre-=Rock genre-=Classic: first Rock then Classic.

3. Values are added in order from the CLI genre+=Rock genre+=Classic: first Rock then Classic.

The order above is not impacted if the CLI options are unordered: genre+=Rock genre=Blues would still do the assignment first.

The deletion genre! is always run last whatever its position. It keeps the compatibility with the actual modify command behavior. To reset a field before adding values, one must use genre= genre+=Rock or artists= artists+=Eric.

Performance

To optimize performance and avoid iterating over a lot of data, the query should prune items as much as possible.

# Only iterate over items without the Rock word in genre
beet multimodify genre+=Rock '^genre:Rock'

# Only iterate over items with the Rock word in genre
beet multimodify genre-=Rock 'genre:Rock'

Limitation

A/ Sub-Optimal Diff

The diff may be sub-optimal as it does not know about the separator. In the following example "Classic Rock" is not highlighted continuously although the final change is still accurate: genre: Hard Rock,**Classic** Rock,**Rock** -> Hard Rock,Rock.

B/ Relation to the original modify command

The modify command has been "copied" and upstream changes won't apply without a port in this plugin.

C/ No order support

I have no need for ordering the values in the tag, as a result, it is always added last.

Grouping/Work fields

mediafile the file level library is using the wrong tag name for MP3 (see issue). As the grouping field was my first motivation to use string multi-value, this plugin is also able to fix the field.

The changes are:

• grouping: for MP3 is changed to GRP1 and ASF does not support it as without a defined value
• work field is added for MP3 (TIT1), MP4 (@wrk), Vorbis (WORK) and ASF (WM/ContentGroupDescription). The values for MP3 and ASF were previously assigned to grouping.

The tags are chosen from Kid3 table.

It is disabled by default so to enable it:

multivalue:
  fix_media_fields: true

It is required to make beets read the tags from the file again as else the kept values in DB are the old ones from the potential wrong fields:

beet update -F work -F grouping

WARNING: As the work field was not saved to the file previously, by reading from the files, it may remove all the work fetched from Musicbrainz and only stored in the DB.