Full audio pipeline from MotionHook → OpenAL 3D playback. Faithful to
retail's 16-voice pool, inverse-square falloff, and SoundTable
probabilistic variant selection.
Core layer (AcDream.Core/Audio):
- WaveDecoder parses the WAVEFORMATEX in Wave dat headers. PCM
(wFormatTag=1) decodes directly; MP3 (0x55) and ADPCM (0x02) return
null + log (ACM compressed decoders need Windows winmm; cross-platform
path deferred). Cites r05 §2.1-2.3 + ACE Wave.cs.
- SoundCookbook.Roll implements the probability-weighted entry pick that
gives retail footsteps their variation. Cumulative-distribution walk;
silence tail when probabilities sum to <1.
- DatSoundCache: ConcurrentDictionary-backed lazy load of Wave /
SoundTable dats, decoded PCM memoized.
App layer (AcDream.App/Audio):
- OpenAlAudioEngine (Silk.NET.OpenAL): 16-source 3D pool with
round-robin first-free, then evict-quieter-slot algorithm matching
retail chunk_00550000.c FUN_00550ad0 exactly. Separate 4-source UI
pool (source-relative). AL buffer cache keyed by Wave id.
InverseDistanceClamped distance model. Fail-open when AL driver
missing or ACDREAM_NO_AUDIO=1 — client continues without audio.
- AudioHookSink routes SoundHook / SoundTableHook / SoundTweakedHook
from the Phase E.1 animation-hook router into OpenAL. All three
hook types fire on both player AND NPCs/monsters (the sequencer
dispatches per-entity and the sink uses entity worldPos for 3D pan).
- DictionaryEntitySoundTable holds per-entity SoundTable mapping,
populated from Setup.DefaultSoundTable at hydration time. Server-
sent overrides would take precedence here when wired.
GameWindow integration:
- OpenAL init in OnLoad after dat collection, suppressible via
ACDREAM_NO_AUDIO=1.
- SetListener called each OnRender frame with camera position + view
basis vectors (fwd = -Z, up = +Y of inverse view).
- AudioEngine disposed in OnClosing before dats.
Tests: 6 WaveDecoder (PCM / MP3-null / ADPCM-null / stereo / truncated
/ peek) + 6 SoundCookbook (empty / single / 50-30-20 distribution
within 5%, silence tail, table lookup, missing table key). Verified
against r05 §2 + ACViewer export-path.
Build green, 497 tests pass (up from 485).
Ref: r05 §2 (Wave format), §5.3 (16-voice pool + eviction).
Ref: FUN_00550ad0 (chunk_00550000.c:527) eviction algorithm.
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
Erik