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Zero-padded track numbers in filenames

Uses Tag → Filename, $num Works on any files with a TRACK tag Time 2 minutes Undo Cmd+Z / Ctrl+Z

The problem

Your file names start with the track number, but some have one digit and some two, and a few also have the total. File managers and car stereos sort them in the wrong order:

Before After
1 Low Tide.mp3 01 Low Tide.mp3
10 Bonus Light.mp3 10 Bonus Light.mp3
2 Lanterns on the Water.mp3 02 Lanterns on the Water.mp3
3-12 Paper Boats.mp3 03 Paper Boats.mp3

Sorted as text, 10 comes before 2. With two digits everywhere, it doesn't.

The solution

Try this on a copy of a few files first. Check the results before applying it to your library; use Edit → Undo in the same session to reverse the recorded changes. Keep the originals as a backup.

  1. Select the files (Cmd+A / Ctrl+A selects all of them).
  2. Choose Convert → Tag → Filename… (Alt+1; Alt is ⌥ Option on a Mac).

  3. Enter this format string:

    $num(%track%,2) %title%

  4. Click Preview, check the new names, then click Apply.

How it works

%track% is the track number as stored in the tag. It can be 2, 02 or 2/12, because many programs store the total after a slash.

$num(x,2) reads the number at the start of x and writes it with at least two digits:

TRACK tag $num(%track%,2)
2 02
02 02
2/12 02
10 10
112 112 (never cut short)

Everything after the first non-digit is ignored, which is how /12 disappears. %title% adds the title, and OpenTag keeps the extension.

Check for files without a track number first

A file without a TRACK tag, or with a vinyl-style track like B2, gets 00. To find such files before renaming, type this into the filter (F3 shows it):

track MATCHES ^[^0-9] OR track MISSING

Number them with Auto-numbering or by hand, then come back.

Variations

Three digits for long compilations or audiobooks

$num(%track%,3) %title%

Disc number in front, only when there is one

[$num(%discnumber%,1)-]$num(%track%,2) %title%

gives 2-05 Salt & Cedar.mp3 on disc 2, and 05 Salt & Cedar.mp3 on an album without disc numbers. The optional section […] disappears when DISCNUMBER is empty.

A separator after the number

$num(%track%,2) - %artist% - %title%

Pad the number in the tag too

To store 02 in the tag itself, use Convert → Tag → Tag… (Alt+5) with the field TRACK and the format string $num(%track%,2). Most players don't need it, but some car stereos sort by the tag text.