Measurement infrastructure for the audio-quality campaign (MMX5 complaint),
ported from snesrecomp's audio_trace/oracle methodology and the
_audio_round2 tap model. No behavior change to the audio path itself.
- audio_trace.{c,h}: three always-on 95 s PCM rings — T1 spu_out (canonical
spu_render output), T2 cd_in (XA/CD-DA PCM entering the SPU CD bus),
T3 host (exact post-fade bytes handed to SDL_QueueAudio) — plus a 512k
event ring (every SPU reg write stamped with the SPU sample clock;
RENDER/PUMP_SKIP/UNDERRUN/MUTE/UNMUTE/CD_PUSH/SPU-DMA), audible-vs-
silent counters (-42 dBFS gate), queue watermarks, and a server-side
44100 Hz WAV dumper (rate exactness matters: snesrecomp da33c06).
- psx-beetle: the libretro audio callbacks stop discarding Beetle's fully-
mixed reference SPU PCM and record it into the same tap ring. Port 4380
gains audio_stats/audio_wav/audio_events with the identical wire protocol
as the runtime (rule 16 symmetric harness) — the oracle WAV capture.
- debug_server: audio_stats / audio_wav / audio_events on the runtime port.
- tools: audio_ab_diff.py + audio_spectral_ab.py (drift-tolerant offline
A/B: drift ppm, onsets, cents, timbre, click rate) and audio_analyze.py
(first-dirty-tap cross-tap decision tree) ported from snesrecomp/
_audio_round2; audio_capture_ab.py dumps both processes symmetrically.
Probes query history; nothing is armed at probe time.
Matthew Stanley