Multi-value fields¶
Why does a player show Juniper Vale; Mira Solberg as one artist when you
expected two? A field can contain one text value with punctuation, or a
list of separate values. Those are different structures even when a screen
renders them similarly.
One field can hold several values¶
Compare three possible ARTIST fields:
| Stored structure | What it says |
|---|---|
One value: Juniper Vale |
One credited artist |
One value: Juniper Vale; Mira Solberg |
One string containing a semicolon |
Two values: Juniper Vale and Mira Solberg |
Two separate artist values |
A semicolon is ordinary text until an operation explicitly splits on it.
The same is true of &, / and commas. Splitting every slash would
damage names such as AC/DC; the punctuation alone cannot reveal whether
it belongs inside one name or separates two names.
Display separators are not stored punctuation¶
OpenTag can display multiple values as:
The two backslashes separate values in that editing/display convention.
They do not mean that the raw tag stores those exact characters between
the names. In the tag panel, entering Juniper Vale \\ Mira Solberg
creates two values and trims surrounding whitespace from each piece.
Extended tags… (Alt+T; Alt is ⌥ Option on a Mac) makes the structure explicit with Value 1, Value 2 and ＋ Add value. Put one whole name in each value box. A semicolon typed inside one box remains part of that value.
Selecting several files introduces another kind of difference: the files may have different artists. Mixed values — keep existing values means the selection differs; it does not mean every file contains the union of all those artists. Leaving a mixed field unchanged preserves each file's existing values.
Format strings choose which values to read¶
For two stored artist values, Juniper Vale followed by Mira Solberg:
| Format string | Result |
|---|---|
%artist% |
Juniper Vale |
$meta(artist) |
Juniper Vale, Mira Solberg |
$meta(artist,0) |
Juniper Vale |
$meta(artist,1) |
Mira Solberg |
$meta_sep(artist,' & ') |
Juniper Vale & Mira Solberg |
A bare placeholder reads the first value. $meta without an index reads
all values using comma-space; indexed $meta starts at 0. $meta_sep
lets the expression choose how to join them. These functions calculate
text; joining text does not preserve the original list structure if that
result is written back as one field value.
Storage depends on the tag format¶
OpenTag's editing model is a list of values per field. The writer must represent that list in the destination format:
| Tag storage | Representation relevant to multiple values |
|---|---|
| Vorbis Comments in FLAC/Ogg-family files | Repeated entries with the same field name |
| APEv2 | Text values separated inside the item by NUL characters |
| ID3v2 | Text-frame value lists and format-specific frames; some fields have a single-value restriction |
| MP4 metadata | Multiple data values; the advanced setting can keep them inside one item atom or write separate item atoms |
| RIFF INFO | One string per INFO identifier; OpenTag joins multiple values with semicolon-space |
| ID3v1 | Limited legacy fields; it cannot represent a general list of values |
The two MP4 layouts can contain the same logical values while being interpreted differently by a player. ID3 revisions and special-purpose fields also have their own constraints. A field that supports several artists does not imply that a numeric field or identifier accepts several values. Read the saved file back and verify the intended player before applying a storage convention to a whole library.
Splitting, joining and deduplicating are different jobs¶
| Operation | Input | Result |
|---|---|---|
Split on ; |
One value: Juniper Vale; Mira Solberg |
Two values: Juniper Vale, Mira Solberg |
Merge with ; |
Two values: Juniper Vale, Mira Solberg |
One value: Juniper Vale; Mira Solberg |
| Remove equal duplicates | Three values: Juniper Vale, Juniper Vale, Mira Solberg |
Two distinct values |
The Split Field by Separator action trims the resulting pieces. Merge Duplicate Fields joins every value, even when the values are different. Remove Duplicate Fields is more destructive with its same-content option off: it keeps only the first value, including when the discarded values were different people. Check that option carefully.
What this means in OpenTag¶
Decide whether the destination player needs separate artists or one display credit. Preserve separate values when they carry useful structure; join them only for a specific display or compatibility goal. Work on copies until the saved tags and player agree.
Editing in Extended tags… stages pending changes; Save tags writes them. An action writes when run. A successful preview or a joined display is not proof that the final file still contains the intended value list.