Filename matching misses the duplicates that matter. Tag matching misses the duplicates that matter. Here's why acoustic fingerprinting is the right tool.
The most common duplicate scenario in a real music library isn't "the same file copied twice" — that's the easy case any tool catches. The hard cases are: the same recording stored at different bitrates with different filenames, the same recording in different formats (320 MP3 vs FLAC), the same recording with different tag spellings ("feat." vs "ft." vs nothing), and the same recording in different folder structures from different import histories. Filename matchers miss every one of those. Tag matchers catch some but miss the bitrate/format variations.
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Acoustic fingerprinting is more expensive than the other methods (you have to decode the audio to compute it), which is why most dedup tools skip it. The cost is worth it for a music library you actually care about — the duplicates that matter are exactly the ones the cheap methods miss. Music Library Doctor uses Chromaprint (the open-source algorithm developed for MusicBrainz Picard) for fingerprinting, layered with file hash and metadata matching for the cheap wins. The Group Scorer then ranks copies inside each duplicate group so the cleanest stays and the others queue for Trash.
No. Different mixes, masters, and remixes produce different fingerprints because the audio is different. Only acoustic-twin copies match.
About 5–10 seconds per track on a modern machine — decoding is the bottleneck. A 10,000-track library completes in 10–30 minutes; cached results are instant for subsequent scans.
Yes. Chromaprint works on any audio. For spoken word, podcasts, or sound effects, the same algorithm groups acoustically identical files.
Only if they can be decoded to PCM. DRM'd files (some Apple Music streams, some old iTunes purchases) can't be analyzed without first authorizing playback. Files you can play through any normal audio app work fine.
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