The MusicBrainz database does not contain genre information. Therefore, when importing and autotagging music, beets does not assign a genre. The lastgenre plugin fetches tags from Last.fm and assigns them as genres to your albums and items.
pip install pylast
After you have pylast installed, enable the lastgenre plugin in your configuration (see Using Plugins).
The plugin chooses genres based on a whitelist, meaning that only certain tags can be considered genres. This way, tags like “my favorite music” or “seen live” won’t be considered genres. The plugin ships with a fairly extensive internal whitelist, but you can set your own in the config file using the whitelist configuration value or forgo a whitelist altogether by setting the option to false.
The genre list file should contain one genre per line. Blank lines are ignored. For the curious, the default genre list is generated by a script that scrapes Wikipedia.
The plugin can also canonicalize genres, meaning that more obscure genres can be turned into coarser-grained ones that are present in the whitelist. This works using a tree of nested genre names, represented using YAML, where the leaves of the tree represent the most specific genres.
When looking up genres for albums or individual tracks, you can choose whether to use Last.fm tags on the album, the artist, or the track. For example, you might want all the albums for a certain artist to carry the same genre. The default is “album”. When set to “track”, the plugin will fetch both album-level and track-level genres for your music when importing albums.
By default, the plugin chooses the most popular tag on Last.fm as a genre. If you prefer to use a list of popular genre tags, you can increase the number of the count config option.
Lists of up to count genres will then be used instead of single genres. The genres are separated by commas by default, but you can change this with the separator config option.
Last.fm provides a popularity factor, a.k.a. weight, for each tag ranging from 100 for the most popular tag down to 0 for the least popular. The plugin uses this weight to discard unpopular tags. The default is to ignore tags with a weight less then 10. You can change this by setting the min_weight config option.
To configure the plugin, make a lastgenre: section in your configuration file. The available options are:
- auto: Fetch genres automatically during import. Default: yes.
- canonical: Use a canonicalization tree. Setting this to yes will use a built-in tree. You can also set it to a path, like the whitelist config value, to use your own tree. Default: no (disabled).
- count: Number of genres to fetch. Default: 1
- fallback: A string if to use a fallback genre when no genre is found. You can use the empty string '' to reset the genre. Default: None.
- force: By default, beets will always fetch new genres, even if the files already have one. To instead leave genres in place in when they pass the whitelist, set the force option to no. Default: yes.
- min_weight: Minimum popularity factor below which genres are discarded. Default: 10.
- source: Which entity to look up in Last.fm. Can be either artist, album or track. Default: album.
- separator: A separator for multiple genres. Default: ', '.
- whitelist: The filename of a custom genre list, yes to use the internal whitelist, or no to consider all genres valid. Default: yes.
In addition to running automatically on import, the plugin can also be run manually from the command line. Use the command beet lastgenre [QUERY] to fetch genres for albums matching a certain query.
To disable automatic genre fetching on import, set the auto config option to false.