- frontend/wasm/loudness.c → loudness-wasm.js (1.5 KB, base64-embedded; built by
scripts/build-loudness-wasm.sh with clang or Zig's clang): K-weighting + 100 ms
energy steps. loudness.js does the 400 ms gating (abs -70 LUFS, rel -10 LU)
with an identical JS fallback. EBU Tech 3341 sine cases measure -23.0/-33.0
on both engines; a real track reads -21.7 vs ffmpeg ebur128 -21.8.
- The device measures from audio it already has (saved copy or the server
cache's m4a sidecar, songs up to 12 min, decoded natively at 22.05 kHz) and
reports the number to /api/loudness, so each song is measured once for
everyone; the server stores numbers only, no audio processing.
- The EQ graph gains a level stage (gain -> limiter) that eases each track
toward -14 LUFS (-12..+9 dB). Settings -> Playback -> Level volume: on by
default on Android/desktop, opt-in on iPhone (Web Audio stops sound when the
screen locks there).
ea9e11d054