Tutorial: make your metadata consistent so your library shines in Luma

What Luma does with your tags

Before cleaning up, it helps to see which field drives which view. This table describes how Luma behaves on iPhone, iPad and Mac:

Two fields other programs know are deliberately not used by Luma: the compilation flag and separate sort fields. For compilations, only the album artist counts in Luma, and sorting goes by what's actually in the field. If tags are missing altogether, Luma takes what it can from the file name and gathers songs without an album under "Unknown Album".

Preparation: back up and take stock

• Make a backup. Tagging programs change hundreds of files in seconds. Copy your music folder to an external drive first.
• Pick a tool. For large collections, MusicBrainz Picard (free, Windows, Mac, Linux) matches albums automatically against the open MusicBrainz database. For targeted fixes across many files at once, Mp3tag is strong (free on Windows, paid on Mac). For single cases Luma itself is enough.
• Find the problem cases. In Luma, sort Library › Albums by artist and scroll through. Look for albums under "Unknown Album" or "Unknown Artist", tiles with only one or two songs, and artist names that appear twice. That's your work list.

Then work album by album in the order of this tutorial. The first steps have the biggest effect.

Step 1: set the album artist

The album artist decides which artist an album belongs to and holds it together. Without it, an album falls apart as soon as one song has a guest. The rules:

• One value for every song on the album, the name the album was released under, usually as printed on the cover.
• Guests go in the artist field, not the album artist. "Daft Punk feat. Pharrell Williams" is the song's artist; "Daft Punk" is the album artist.
• Same artist, same spelling. "AC/DC" and "ACDC", "Beyoncé" and "Beyonce", or "The National" and "National" each make two artists in Luma.
• Compilations with many performers get a shared album artist such as "Various Artists". Pick one variant and use it everywhere; MusicBrainz and Picard use "Various Artists".
• Collaboration albums by two artists get a shared value, such as "Jay-Z & Kanye West". The album then appears under that name as an artist of its own.

Step 2: album titles and editions

The album title must also be identical on every song. Typical pitfalls:

• Edition suffixes: "Rumours", "Rumours (Remastered)" and "Rumours [Deluxe Edition]" are three albums. If you only want one version, remove the suffixes. If you deliberately keep two versions, leave them different.
• Multi-disc sets: no "(Disc 1)" and "(Disc 2)" in the album title. The disc belongs in the disc number field, or the double album becomes two albums.
• Spaces and punctuation: double spaces, different apostrophes (' and ’) or hyphens instead of colons are invisible reasons for duplicate albums. Luma only trims spaces at the start and end.
• Singles and EPs get their own title as the album name, so they sit in the discography as small releases and don't merge with the album.

Step 3: track and disc numbers

Luma sorts the track list by disc number first, then by track number. Values like "3/12" are understood; the first number counts. Without a disc number, disc 1 is assumed. On double albums, box sets and deluxe editions with a bonus disc, every disc should therefore have its number, and track numbers start again at 1 on each disc. Without track numbers, songs don't play in album order, and gapless transitions on live albums no longer line up.

Step 4: give every album a year

The year controls three things in Luma: sorting by release year in the albums view, the order of the discography on the artist page, and dynamic playlists with a year rule, for a decade for example. Without one, an album sits at the very front of the artist page, ahead of the debut. Watch out for:

• Format: Luma reads the first four characters. "1977" and "1977-02-04" work; "04/02/1977" doesn't.
• Original or reissue: for a coherent discography and playlists by decade, the original release year is usually better. A 2011 remaster of a 1977 album belongs in the seventies musically. How to fill in the original year automatically with Picard is covered under tools below.
• Consistent within the album: every song on an album gets the same year. Luma takes the album year from the first song it imports. Different years on compilations, such as each original song's year, mean only part of the compilation shows up in a playlist by decade. That can be intended, but rarely is.

Step 5: a small, fixed genre vocabulary

Genres are the messiest field in most collections, because every store and database uses different terms. In Luma they drive dynamic playlists with a genre rule and help in album search, for example when building a collection. Three rules:

• One genre per song. Luma reads the first genre. If a field says "Rock; Pop; Indie", it becomes a single, very specific genre with exactly that name.
• A fixed list. Ten to twenty genres are enough for most collections. Each genre should have enough albums to make a dynamic playlist of its own worthwhile.
• Same across the album. If you edit the genre in Luma through Edit Album Info, Luma applies it to every song.

An example of a lean vocabulary you can adapt:

Finer divisions like "shoegaze" or "deep house" are better handled with collections or playlists. There an album can sit in several groups; in the genre field it can't.

Step 6: embed the artwork

Luma takes the artwork from the file, specifically the first embedded image. It doesn't read a loose cover.jpg in the folder. That means:

• Front cover first. Some downloads contain several images (back, booklet). If the front cover isn't first, Luma may show the back. The simplest fix is to embed only the front cover.
• 1,000 to 1,500 pixels is enough. Luma scales every cover to about 1,024 pixels. Larger embedded images cost storage in every song without looking better in Luma. How much that adds up to in large collections is in organising a music library.
• Same artwork across the album. Luma uses the cover of the first song that has one for the album. Different images within an album lead to surprises.

You can also set artwork in Luma: in Edit Album Info, tap the cover and choose an image from Photos or Files; on the Mac, just drag an image from Finder onto the cover.

Step 7: titles and artists

• Note guests consistently. Either "Song" with artist "A feat. B", or title "Song (feat. B)" with artist "A". Luma displays both sensibly; what matters is using one way consistently.
• Align capitalisation. "Here Comes The Sun" versus "Here Comes the Sun" is a matter of taste for display and irrelevant to Luma's duplicate detection, but not for album and artist names, where every character counts.
• No additions that aren't part of the title, such as file-name leftovers like "01 - " or "[www.something.com]". Mp3tag removes such patterns in one pass.
• Mark versions. "Song (Live)", "Song (Acoustic)" or "Song (2011 Remaster)" in the title keeps two versions on different albums distinguishable, including in playlist backups.

Step 8 (optional): lyrics

Luma shows lyrics from the file's lyrics tag or from an .lrc file with the same name next to the song. With timestamps they follow along line by line in the player. Embedded lyrics are the more robust choice, because they travel with the file everywhere, including via Luma Transfer to the iPhone, which only sends audio files. Details are in the help center under Showing lyrics.

Special cases

Setting up your tools

MusicBrainz Picard

Picard matches your files to releases in MusicBrainz and then writes complete, consistent tags, including album artist, numbers and "Various Artists" on compilations. For Luma, these settings are worth it:

• Genres: turn on "Use genres from MusicBrainz" and set "Maximum number of genres" to 1 (the default is 5). With several genres, Picard joins them with a separator into one field, which Luma reads as a single genre. The genre filter lets you restrict the choice to your vocabulary.
• Artwork: turn on embedding, embed only the front cover, and choose 1,200 pixels as the size. That's close to what Luma displays.
• Year: Picard writes the date of the chosen pressing into the year field and the original release date into a separate field that Luma doesn't read. If you want the original year, add a line like $if(%originalyear%,$set(date,%originalyear%)) under Scripting in Picard's options.

Mp3tag

• Many files at once: select every song of an album and set album artist, album, year and genre in one go.
• Actions: convert case, replace characters, strip additions with regular expressions. Once created, an action can be applied to the whole collection.
• Filter: a filter such as albumartist MISSING shows every file without an album artist at a glance.
• Tag version: for MP3, ID3v2.3 with UTF-16 is the most compatible choice and the default.

Fixing things right in Luma

For single cases you don't need to leave the app. Touch and hold a song or album (on the Mac: right-click) and choose Edit Info or Edit Album Info. Edit Album Info changes album, album artist, year, genre and artwork for every song at once. If you rename an album so its name and album artist match an existing one, the two merge.

• On the Mac, Luma writes changes straight into your original files in the added music folders, for MP3, M4A and FLAC. Only the changed fields are touched; the audio stays identical byte for byte. While you type, Luma suggests artists, album artists and genres from your library, which avoids typos and variants. That makes Luma for Mac a good tool for making your archive consistent.
• On iPhone and iPad, Luma writes into its own copy of the file; your originals stay unchanged. To get the corrected files onto your computer too, use Export Library.
• WAV and AIFF have no reliable tags. Edits there apply only within Luma. If you have these formats, convert them losslessly to FLAC for your collection.

Playlists survive the clean-up: when you change title, artist or album in Luma, every playlist entry follows. How Luma matches songs in playlist backups is in How Luma recognises and matches songs.

Clean up before or after importing?

Ideally before, on the computer, with the archive as the basis. Then the tags in your original files are right, and every device and player benefits. On the iPhone, importing makes a copy: if you've already imported there and then changed tags on the computer, importing again would add the changed songs as new ones. So remove the affected albums in Luma first, then import them again. On the Mac this isn't necessary: Luma for Mac rereads the folders at launch or with ⌘R and picks up changed tags without losing likes, play counts or playlist positions.

Checklist per album

• Album artist the same on every song, guests only in the artist field.
• Album title the same on every song, without a disc suffix.
• Track numbers complete, disc numbers on multi-disc sets.
• One year in YYYY format, the same on every song.
• One genre from your vocabulary, the same on every song.
• Front cover embedded, first in line, 1,000 to 1,500 pixels.
• Titles without file-name leftovers, versions as a suffix in the title.

Frequently asked questions

Sources

• MusicBrainz Picard documentation: genre options. picard-docs.musicbrainz.org/en/latest/config/options_genres.html
• MusicBrainz Picard documentation: Cover Art Archive (image sizes). picard-docs.musicbrainz.org/en/latest/config/options_cover_art_archive.html
• MusicBrainz Style Guide: Artist Credits, rules for compilations and "Various Artists". musicbrainz.org/doc/Style/Artist_Credits
• Mp3tag help (actions, filters, tag versions). help.mp3tag.de
• ID3.org: ID3 tag version 2.4.0, Native Frames. id3.org/id3v2.4.0-frames

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