open-standards/wai/pack-conformance/loudness/README.md

pack-conformance/loudness — integer loudness and the loudness statement

The corpus of extensions/packaging.md §12, in one file, vectors.json.

Provenance. Generated here by wai_loudness_vectors gen (wai-rs, feature loudness): programmes given as formulas of integers (one period of a 1 kHz tone at 48 kHz, sine_1k, which the text and the generator state; a linear congruential generator's noise; silence), their measurements, and statements signed with an Ed25519 key on a fixed 32-byte seed; no recording and no input from outside this repository.

• programmes (§12.2, §12.3) are each a rate, a number of channels and segments, each of frames sample frames with a source a channel: zero; tone, sine_1k[k mod 48] × num / den, floored, for the segment's frame k; noise, from x = seed, each sample x ← (x × 1 103 515 245 + 12 345) mod 2^31 then ⌊x / 2^8⌋ mod (2·amp + 1) − amp; spike, the same noise with frame at at 32 767. outcome is the measurement: frames, blocks, gated, integrated_milli, peak, peak_milli.
• logarithms (§12.3) are pairs of an integer and its L, both in decimal, the integer from 1 to 2^128 − 1.
• statements (§12.5, §12.6) are each a statement's text, the receipt_hash a verifier expects (or null) and the programme it holds as its source (or null); outcome is verified, with the component, loudness, gain and limited, or refuse and the reason.

Everything is synthetic: the key attests nothing. The generator holds each programme to the loudness BS.1770's calibration or the programme's construction declares, and each statement's outcome is the one it was written to have.

wai_loudness_vectors verify and tests/loudness.rs check that the file regenerates byte for byte and that wai-rs reaches every stated outcome. ../loudness_verify.py is the second implementation, written from the extension's text, which also mutates copies of the corpus and drops each of its own checks in turn and requires each to be caught.