internal/acoustid posts AcoustID's v2 lookup as a gzip form with
meta=recordings, one request per 400ms (their limit is 3/s) and a 20s
deadline. It returns every linked recording with its best score; choosing
among them is the worker's job (D5). The server's error codes map to an
invalid key (stop and say so), a rejected fingerprint (a verdict on the
track) or unavailable (try again later). A cancelled caller stays a
cancellation.
fpcalcLookupArgs and parseFpcalcCompressed read fpcalc's default output,
the compressed string the lookup takes (D1), always over the first 120s.
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
bvandeusenandClaude Opus 5.5
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