Audio

The Audio tab holds two different ways of matching music, chosen from one dropdown. One reads the tags. One listens to the recording. Picking the wrong one is the usual reason a music search comes back empty, so start here.

Run a scan first — the match reads the scan results rather than searching your drives.

Which one do you want?

If your files are well tagged, match by tags. If they are not, match by sound. That is the whole decision.

Your library Choose Why
Bought or ripped, with proper artist/title tags Exact, Similar or Approximate Quick — Trawler reads only the tags, never the audio
Downloaded, untagged, or tagged inconsistently By sound The only choice that works when the tags are missing or wrong
The same recording at different bitrates By sound The tags may not agree; the audio does
The same song across different albums A tag mode Two different recordings will not sound alike

The dropdown starts on By sound.

The four choices

Choice On screen What it compares
By sound "Listens to the audio" The recording itself. Ignores tags completely.
Exact "Exact match" Artist and title must agree, after tidying.
Similar "Allows typos" Same, but tolerates spelling differences.
Approximate "Allows remixes & reordering" Same, more loosely still — catches reordered and decorated titles.

Telling the results apart

Each group carries a badge saying how it was found:

  • Audio · tags — matched on tags.
  • Acoustic · N% — matched on sound. The percentage is the weakest pairing in the group, so a group reading 88% has no member below that.

Matching by tags

Trawler reads each file's artist, title, album and length — it never opens the audio, so this is fast even on a large library.

A file with no artist, no title, or no readable length is never grouped this way. Untagged rips simply do not appear. That is the case for By sound.

"Exact" is not literally exact. Before comparing, Trawler tidies every tag: it ignores case, accents, curly quotes, punctuation, a leading The / A / An, anything from feat. onwards, and a trailing bracketed note such as (Remastered), [Explicit], (Radio Edit) or (Deluxe). So "The Beatles" and "Beatles" group, and so do "Hey Jude" and "Hey Jude (2009 Remaster)".

Controls:

Control Range Starts at What it does
Threshold 50–100% 75% How closely titles and artists must agree. Only active for Similar and Approximate — Exact ignores it.
Duration ± 0–30 s 2 s How far two tracks' lengths may differ and still group.
Include album on / off off "Include the album tag in the match too (stricter)." Turn it on to stop an album track grouping with its best of copy.

Changing any of these re-runs the match immediately — it costs almost nothing.

Matching by sound

By sound decodes part of each track and compares the audio. It finds the same recording across different formats and bitrates, and it works on files with no tags at all.

It is much slower than tag matching, because every file has to be read. The first run is the expensive one, and it never starts on its own: switching the dropdown to By sound clears the list, and you start the run with Find similar audio.

Switching to one of the three tag modes fills the list straight away when the work has already been done — a scan that included audio does both kinds of matching, so both are usually ready and waiting. When it has not been done, the tag match simply runs, because that costs almost nothing.

Control Range Starts at What it does
Similarity 50–100% 85% How alike two tracks must sound to group.
Window 5–60 s 15 s How much of each track is listened to. Longer is more reliable on tracks that share an intro.

Hover either slider to read its current setting; while you drag, the figure follows the handle.

Moving Similarity re-groups what has already been read. Moving Window does not: a different window means every track has to be read again, so Trawler shows "Settings changed since the last audio match." with Re-run and Revert. Revert puts the setting back and keeps your current results.

The file types each method covers

They are not quite the same list.

By tags By sound
.mp3 .flac .m4a .ogg .aac .aiff Yes Yes
.wav No Yes

.wma is played and counted, but neither method can match it.

Nothing is picked for you

"Matches are advisory — tracks may differ in content or quality. Mark each file you want to remove; nothing is selected for you."

Each member row shows its format, bitrate, length and size so you can judge which copy to keep. Replace with hardlink is not offered on Similar results.

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