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Tag → Tag

Use Tag → Tag to copy or calculate one destination field from existing tags. Its preview refreshes as you change the field or format string, so you can learn an expression before saving it in an action.

Fill missing album artists

  1. Keep copies, save pending edits and select practice files.
  2. Choose Convert → Tag → Tag… (Alt+5; Alt is ⌥ Option on a Mac).
  3. Enter ALBUMARTIST in Field.

  4. Enter this Format string:

    $if2(%albumartist%,%artist%)

  5. Wait for the preview to finish. An existing album artist should remain; a missing one should receive the artist value.

  6. Choose Apply to … files to write the reviewed values immediately.

$if2 chooses the first nonempty argument. With ARTIST = Juniper Vale, the result is Juniper Vale only when ALBUMARTIST is empty. Entering %artist% alone would replace existing album artists as well.

Expressions to try

Destination field Format string Input Result
ALBUMARTIST %artist% ARTIST = Juniper Vale Juniper Vale
YEAR $left(%year%,4) YEAR = 2024-05-01 2024
TITLE $trim(%title%) TITLE = Paper Boats Paper Boats
COMMENT Library copy Any existing comment Library copy
TRACK $num(%track%,2) TRACK = 3/8 03

For ordinary metadata fields, two consecutive backslashes (\\) in the evaluated output separate values, as in Format Value. With that delimiter, each component is trimmed and empty components are dropped; if no values remain, the field is removed. The preview shows the surviving values joined with \\, or Field will be removed if none remain. Without the delimiter, a nonempty output is one value whose surrounding whitespace is kept.

A bare placeholder reads only the first existing value. For example, $meta_sep(artist,\\) writes the existing artists as separate values, while $meta_sep(artist,' & ') writes one joined value. Read the multivalue rules before replacing artist or composer lists. Filename/directory targets use the naming rules below instead of splitting metadata values.

An empty result removes the destination field. The preview labels that outcome Field will be removed. '' produces an apostrophe, not empty text; see quoting.

Rename from the same dialog

The two special destinations are _FILENAME and _DIRECTORY:

Field Format string Effect
_FILENAME $num(%track%,2) - %title% Build a filename and retain the audio extension
_DIRECTORY %album% Rename the containing folder from the album

These destinations use filename evaluation: literal separators can create folders, while separators from field values use the configured replacement. An empty generated name disables applying the conversion.

A folder rename affects the folder itself, potentially including files outside the selection. Practice with a copied folder, and use Tag → Filename when reviewing a full file-and-folder layout is the goal.

Gotchas

  • Applying saves immediately, unlike editing the tag panel.
  • Changing the expression or field invalidates the previous result until the automatic preview finishes. Review the final version before applying.
  • At most the first 100 preview rows are displayed, even when more files are selected. Split a large unfamiliar collection into smaller batches.
  • _TAG, _ALL and technical information placeholders are not destination fields. Choose an ordinary tag field or one of the two naming targets.
  • Keep copies and inspect operation errors and Edit → Undo for recorded changes in the current desktop session.