The first step of loudness normalization: the server measures each track
with ffmpeg's EBU R128 filter (true peak, mono as dual mono) and stores the
integrated loudness, true peak and loudness range in track_loudness
(migration 0065).
It also keeps a histogram of the 400 ms gating blocks at 0.1 LU, so album
loudness can be computed exactly later with no second decode (#4996). The
histogram reproduces ffmpeg's own figure (-10.68 against -10.7 on the
captured fixture), and the analyzer logs a warning if the two ever drift.
- A background worker, cloned from the fingerprint backfill, measures every
track, new ones included. Measuring inline in the scan was dropped: the
analysis decodes the whole file, and a large import could pass the scan's
one-hour stuck threshold. The scan only deletes a changed file's
measurement; the worker ticks every 10 minutes.
- Timeouts, the cancel/missing-binary split and settled verdicts follow the
fingerprint runner. Silence and undecodable files are stored as verdicts;
stalls are retried. The deadline scales with track length.
- loudness_settings (enabled, files at once) and an admin card with the
coverage gauge, under GET/PUT /api/admin/library/loudness-settings and
GET /api/admin/library/loudness.
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
