How to use in paths unsupported tags from file?

[sylph1o]

Hi everyone!

I discovered recently this wonderful piece of FOSS and I am very excited to migrate my current library to beets. I have been looking at the feasibility of this, and particularly at the best way to reproduce my file organisation with beets.

I have discovered (from beet fields, the documentation and the code) that some metadata fields I use are not supported, although they are supported by MusicBrainz; e.g.

• albumsort,
• titlesort,
• originalartist.

I understand that originalartist is not very common. However, I am surprised that albumsort and titlesort are not supported, while artistsort and albumartistsort are. I currently rely on the values stored albumsort and titlesort (in the files) for the paths of my music library. I have found no mention of these fields, neither in the discussion board nor this Github project, so the feature must not be in high-demand. I am looking for a way to work around this limitation and be able to use the values stored in these fields in the paths defined by beets, preferably with minimal effort.

I thought flexible attributes could be a solution, using something like beet import --set albumsort=$albumsort, but unsupported tags stored in the files are simply not accessible from beets (not even during import). Is there a way for me to provide this value for each file from an external tools? For example, the following shell command return the value stored in the albumsort field of the file, but I do not know how to let beets read that for each file.

ffprobe -v 0 -select_streams a:0 -show_entries stream_tags=albumsort /path/to/file.ogg | grep TAG | sed "s/TAG:albumsort=//g"

I guess I could write a shell script to loop over all files, read the tag with ffprobe as above and set a flexible attribute with beet modify, but that seems inefficient.
Does anyone have an idea to contribute? Any thought is welcome!

[sampsyo]

Good question! The way to add support for custom on-disk tags is to write a (very small) plugin that provides a media file specification:
https://beets.readthedocs.io/en/stable/dev/plugins.html#extend-mediafile

This way, you can provide beets field names for any metadata tags you like.

[sylph1o]

Thanks, this addresses my needs perfectly! I was able to add support for the tags I want, and to define the template fields I want to use in my paths. The plugin interface and good documentation made it surprisingly easy, so I'm grateful for that too.

Although my question has been answered, I have two remarks to add as feedback.

First, the plugin documentation explains how to use pkgutil to place the plugin (a Python module) inside the namespace package beetsplug and refers to this question on StackOverflow. The top-level answer there explains that pkgutil is no longer necessary since Python 3.3 introduced implicit namespace packages. I don't know if there is a reason why the documentation of beets still recommends to use pkgutil. I can only say that didn't use it and my plugin was loaded without issue.

Second, after loading my plugin, beets is now able to import the new metadata tags (e.g. titlesort) in its database when running beet import <path>. However, beets throws an error when I try to update an entry already existing in the database (i.e. with a titlesort tag in the file that was not read at import) with

beet update -F titlesort <query>

The error trace is copied below.

Traceback (most recent call last):
  File "/usr/sbin/beet", line 33, in <module>
    sys.exit(load_entry_point('beets==1.6.0', 'console_scripts', 'beet')())
  File "/usr/lib/python3.10/site-packages/beets/ui/__init__.py", line 1285, in main
    _raw_main(args)
  File "/usr/lib/python3.10/site-packages/beets/ui/__init__.py", line 1272, in _raw_main
    subcommand.func(lib, suboptions, subargs)
  File "/usr/lib/python3.10/site-packages/beets/ui/commands.py", line 1211, in update_func
    update_items(lib, decargs(args), opts.album, ui.should_move(opts.move),
  File "/usr/lib/python3.10/site-packages/beets/ui/commands.py", line 1163, in update_items
    item.store(fields=fields)
  File "/usr/lib/python3.10/site-packages/beets/library.py", line 344, in store
    super().store(fields)
  File "/usr/lib/python3.10/site-packages/beets/dbcore/db.py", line 528, in store
    tx.mutate(query, subvars)
  File "/usr/lib/python3.10/site-packages/beets/dbcore/db.py", line 866, in mutate
    cursor = self.db._connection().execute(statement, subvals)
sqlite3.OperationalError: no such column: titlesort

This is not really a problem for me: I can simply remove the entry and import it again. I'm simply reporting the unexpected behaviour. Would you like me to open an issue about it?

[sampsyo]

It's a great idea to remove the old documentation about pkgutil. We should almost certainly just delete this. If you have a chance, a PR doing just this would be extremely helpful.

The crash when doing beet update looks like it could be a bug! It looks like this code is expecting to support flexible attributes (it only supports fixed attributes, which correspond directly to SQLite columns). Maybe we should take this to a separate GitHub issue to investigate.