Songs with multiple artists get tagged incorrectly

[genericCandy]

I'm not really sure if that's a bug or intended behaviour (i opened discussion #6856 about this but nobody replied), but when a song or album contains multiple artists (for example A & B), beets lumps them together into a single artist (that in this example would be called A & B), which clutters the library.

Problem

Running ffprobe on a relevant file shows that there is a single artist tag that lumps together all the artists, instead of one tag per artist:

TAG:title=KAYFABE
TAG:artist=Ptite Soeur & Gemroz
TAG:track=5/6
TAG:album=KAYFABE CHIMERA
TAG:disc=1/1

Setup

I don't think that's very relevant but anyway:

• OS: Arch Linux
• Python version: 3.14.7
• beets version: 2.14.0
• Turning off plugins made problem go away (yes/no): no

Config file:

# --------------- Main ---------------

library: ~/.config/beets/library.db
directory: ~/Music

# --------------- Plugins ---------------

plugins: musicbrainz embedart fetchart replaygain mbsync
replace:
    '[\\/]': _
    '[\x00-\x1f]': _
    \.$: _
    ^\.: _
    \s+$: ''
    ^\s+: ''
    ^-: _
artist_credit: no

# --------------- Tagging ---------------

per_disc_numbering: yes

ui:
    color: yes

import:
    log: ~/.config/beets/import.log
    move: yes
    timid: yes
musicbrainz:
    extra_tags:
    - year
    - catalognum
    - country
    - media
    - label
    genres: yes
    search_limit: 5
    data_source_mismatch_penalty: 0.5
    search_query_ascii: no
    genres_tag: genre
    external_ids:
        discogs: no
        bandcamp: no
        spotify: no
        deezer: no
        tidal: no
    aliases_as_credits: no
paths:
    default: $albumartist/$album%aunique{}/$disc-$track $title
    albumtype:soundtrack: Soundtracks/$album/$disc-$track $title
    singleton: Non-Album/$artist/$title
    comp: Compilations/$album%aunique{}/$disc-$track $title
replaygain:
    auto: no
    backend: ffmpeg
    overwrite: no
    threads: 12
    parallel_on_import: no
    per_disc: no
    peak: 'true'
    targetlevel: 89
    r128: [Opus]
    r128_targetlevel: 84
scrub:
    auto: no
lyrics:
    auto: no
fetchart:
    enforce_ratio: 2%
    auto: yes
    fetch_for_asis: no
    minwidth: 0
    maxwidth: 0
    quality: 0
    max_filesize: 0
    cautious: no
    cover_names:
    - cover
    - front
    - art
    - album
    - folder
    fallback:
    sources:
    - filesystem
    - coverart
    - itunes
    - amazon
    - albumart
    - cover_art_url
    store_source: no
    high_resolution: no
    deinterlace: no
    cover_format:
    fanarttv_key: REDACTED
    lastfm_key: REDACTED
    google_key: REDACTED
    google_engine: REDACTED
embedart:
    auto: no
    remove_art_file: yes
    maxwidth: 0
    compare_threshold: 0
    ifempty: no
    quality: 0
    clearart_on_import: no
disabled_plugins: []

[frigorific44]

This is intended behavior. You can search the forums to see others confirming this:
https://discourse.beets.io/t/multiple-artist-i-just-want-the-first-one/416/2
https://discourse.beets.io/t/custom-naming-with-multiple-artists/1695

Tags only contain a single value, so I'm not sure what you mean when you talk about one tag per artist? Tags are a series of keys and values, with both the key and value being a single string. So with multiple artists, what should "artist" contain? Only the first artist? To separate them, you'd need "artist1", "artist2", and so on. I'm not sure how this is handled elsewhere, but at some point there'd need to be a delimitter separating them so they can be stored in a single value.

Also, if you think about it as a file taxonomy where there are artists, and artists have releases, and releases have tracks... If a release has multiple artists, then where does it go? Beets would have to make an arbitrary choice as to which artist's path to store it under. For that release you mentioned, if you look on MusicBrainz both of those artists have the release listed under them, but for choosing file locations you can't really choose two file locations simultaneously.

Now, that's just if it's stored in one location. I think a nice solution could be moving the release to the first artist when importing it, and then creating links to that release's directory in all the other artist paths, but I think that would be more the purview of a plug-in.

Sorry if I've misunderstood something, and other places may handle this better (as in not beets), but by and large this is the default and expected behavior. Again, looking through forums and elsewhere you might find solutions which relieve the clutter in someway, as you certainly aren't the only person who has felt that something was wrong with doing it like this.

[snejus]

>>> from mediafile import MediaFile

>>> MediaFile(Path("/mnt/music/Music/futuresoundz/kfs005_houserepublicvsdjamadeus_flashdancewhatafeeling/02_flashdancewhatafeeling.mp3")).artists
['House Republic', 'DJ Amadeus']

>>> MediaFile(Path("/mnt/music/Music/dreaminglive/enough/21_zuliftotteswed_wHwshbdwnsmy.flac")).artists
['ZULI', 'Ott Eswed']

beets does write multiple artists to FLAC files since this format supports multiple artist spec:

$ metaflac --block-type VORBIS_COMMENT --list /mnt/music/Music/dreaminglive/enough/21_zuliftotteswed_wHwshbdwnsmy.flac | grep -E 'ARTISTS?='
    comment[3]: ALBUM ARTIST=Various Artists
    comment[4]: ALBUM_ARTIST=Various Artists
    comment[5]: ALBUMARTIST=Various Artists
    comment[8]: ALBUMARTISTS=Various Artists
    comment[9]: ALBUM_ARTISTS=Various Artists
    comment[17]: ARTIST=ZULI ft Ott Eswed
    comment[20]: ARTISTS=ZULI
    comment[21]: ARTISTS=Ott Eswed

On the other hand, multiple artists are not written to MP3 files:

$ mid3v2 -l /mnt/music/Music/futuresoundz/kfs005_houserepublicvsdjamadeus_flashdancewhatafeeling/02_flashdancewhatafeeling.mp3 | grep TPE  
TPE1=House Republic Vs DJ Amadeus
TPE2=House Republic Vs DJ Amadeus

I see that id3v23 does not support multiple artists while id3v24 does: https://www.perplexity.ai/search/20d4d453-74de-4222-9e7d-94863a5bb6c3

[genericCandy]

About the multiple ARTIST tags, I read this on this MPD issue and assumed that there could be multiple ID3 tags of the same kind, but apparently it is not the case, I'm not sure what they mean.

Then I searched exactly what format MPD expects, and found out this comment that says that with Kid3, you can just add multiple ARTIST/ALBUMARTIST tags, and MPD will correctly recognize that. I tried it and indeed, this is the correct behaviour for MPD.

Looking at a working file file with mid3v2 shows that the MPD's delimiter is a "/", but there is apparently a newline at the end for some reason ?

TLAN=fra
TMED=Digital Media
TPE1=Ptite Soeur / Gemroz

TPE2=Ptite Soeur / Gemroz
TPOS=1/1
TRCK=5/6

(MPD correctly handles TPE1 as 2 artists but not TPE2)

I tried to replicate this by manually adding the extra \n with mid3v2, but I get an error:

$ mid3v2 --TPE1 $(echo -e "Ptite Soeur / Gemroz\n") "Music/01-05 KAYFABE.mp3" 
[Errno 2] No such file or directory: ''

EDIT: the output from mid3v2 doesn't tell the whole story, since a file with artists "A" and "B" and a file with artist "A / B" produce the same output. So I made 2 files, one with "artist 1", "artist 2" and "artist 3", and the other with "artist 1" and "artist 2 / artist 3", and here is the binary diff:

@@ -449545,23 +449545,23 @@
 006dc080: f3be 4c2b 87ed f3d5 b4e9 cd8b 6d8d dff4  ..L+........m...
 006dc090: ba7d b66d 9e3a baf2 61c1 3e99 6adf 8593  .}.m.:..a.>.j...
 006dc0a0: 0351 dda0 6bf5 8d07 fedc 0b7d 7ee6 f7b4  .Q..k......}~...
 006dc0b0: 9253 85d6 37bf eaf1 fdfb 14ed 415f eba7  .S..7.......A_..
 006dc0c0: f868 3bb4 dd70 d992 4dbd 6cd7 f5de 6c35  .h;..p..M.l...l5
 006dc0d0: d841 fad5 7ef9 6d72 bbdd bfda ebcc 7667  .A..~.mr......vg
 006dc0e0: adcb 9142 4805 9eba fbbb 2b36 2e77 fe85  ...BH.....+6.w..
 006dc0f0: fa8a fd5e 7727 d807 19ee bed6 f26c 4ab3  ...^w'.......lJ.
 006dc100: 3bd2 d6b5 832b 7b52 d6de f8ff 0106 9103  ;....+{R........
 006dc110: c55a 1310 7000 0000 0049 454e 44ae 4260  .Z..p....IEND.B`
-006dc120: 8254 5045 3100 0000 0900 0000 6172 7469  .TPE1.......arti
-006dc130: 7374 2032 5450 4531 0000 0009 0000 0061  st 2TPE1.......a
-006dc140: 7274 6973 7420 3300 0000 0000 0000 0000  rtist 3.........
+006dc120: 8254 5045 3100 0000 1400 0000 6172 7469  .TPE1.......arti
+006dc130: 7374 2032 202f 2061 7274 6973 7420 3300  st 2 / artist 3.
+006dc140: 0000 0000 0000 0000 0000 0000 0000 0000  ................
 006dc150: 0000 0000 0000 0000 0000 0000 0000 0000  ................
 006dc160: 0000 0000 0000 0000 0000 0000 0000 0000  ................
 006dc170: 0000 0000 0000 0000 0000 0000 0000 0000  ................
 006dc180: 0000 0000 0000 0000 0000 0000 0000 0000  ................
 006dc190: 0000 0000 0000 0000 0000 0000 0000 0000  ................
 006dc1a0: 0000 0000 0000 0000 0000 0000 0000 0000  ................
 006dc1b0: 0000 0000 0000 0000 0000 0000 0000 0000  ................
 006dc1c0: 0000 0000 0000 0000 0000 0000 0000 0000  ................
 006dc1d0: 0000 0000 0000 0000 0000 0000 0000 0000  ................
 006dc1e0: 0000 0000 0000 0000 0000 0000 0000 0000  ................

It would be nice to have the ability to retrieve all individual artists from the source, and to have an option to select the separator (and ending character apparently?) between multiple artists in the config file.

As for the location of the files in the library, I think the current behaviour is fine since most music players abstract the directory structure anyway, and while having symlinks could be nice in certain situations, I think it is more appropriate for a plugin to implement this.