sylph-decoder cf3b60180e re: withdraw a stream-selection recommendation that contradicted itself
The port implemented "take the highest-rate stream" and reported that on ADV it
selects the QUIETER presentation -- chunk 2, 1171516 B at -8.3 dBFS, over
chunk 1, 1118268 B at 0.0. They were right to flag it rather than accept it.

My sentence was "the highest-rate, highest-gain one is chunk 1". Those two
criteria do not select the same stream and the sentence should never have joined
them; the parenthetical named chunk 1 while the rule named chunk 2. Withdrawn.

What the header does decode, read off the bytes: the fmt chunk is a 32-byte
XMAWAVEFORMAT, little-endian, and +0x20 is a declared PsuedoBytesPerSec -- 8142
and 8530 on ADV s two presentations, agreeing with the computed rates to 0.02
percent, with 48000 Hz at +0x24. So the rate is decoded rather than inferred.

What it does not decode: wEncodeOptions (0x10d6), channel count and channel mask
are byte-identical across the presentations. Nothing in the header ranks them,
so stream selection stays an authored choice and the port must know it is
authoring. Settleable in one emulator run -- a capture of the intro with the
dialogue audible says which level the game plays -- and not yet done.

Also records that sylpheed-cli audio info is misaligned for XMA1: its "16
channels / 4310 Hz / 2-bit" is wBitsPerSample, wEncodeOptions and the channel
fields read at the wrong offsets.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01QsEPXWVaEpyfudtR6re1Pd
2026-08-29 15:13:20 +00:00

Sylpheed

A clean-room reverse engineering and port project for Project Sylpheed: Arc of Deception (Xbox 360, 2007).

Three things live here, in one repository so that a change spanning them lands as one commit:

The decoders crates/sylpheed-formats — the disc's formats, read and verified disc-wide
The port port/ — a Godot 4 project, plus crates/sylpheed-export which converts a disc into the open asset tree it reads
The corpus docs/re/ — what has been reverse engineered, with its evidence, its retractions and its dead ends

You need your own copy of the game. No game content is in this repository and none ever will be. The exporter reads the disc you supply.

The oracle is the real game

sylpheed-cli and the Explorer are tools for verifying our decoding. They are hypotheses under test and they have been wrong. When something must be checked against the truth, the truth is the game running in Xenia Canary, captured — not any renderer of ours.

This is stated first because getting it backwards is the most expensive mistake this project has made.

Layout

crates/
  sylpheed-formats/   the decoders. Disc-wide verified; the corpus is its spec
  sylpheed-cli/       headless tools -- render a screen, dump a table, probe audio
  sylpheed-viewer/    the Explorer: a human's window onto the disc. STATIC data only
  sylpheed-export/    disc -> the open, moddable asset tree
port/                 the Godot 4 project. Reads open formats ONLY
authored/             decisions that are NOT on the disc, each with its reason
data/
  base/               generated by the exporter. Gitignored, never hand-edited
  mods/               drop-in overrides. Yours
docs/
  re/                 the corpus: findings, refutations, method traps
  game/               how the game is navigated -- menus, modals, flight
  port/               the port's mission, its handoff contract, modding rules
  agents/             how the agent team works together
tools/                capture harnesses, probes, the share tool
exchange/             transient inter-agent files. NOT in git
docker/               the agent containers

Where to start

Xenia Canary is a separate repository: it is a fork tracking upstream, and it carries our instrumentation.

Conventions

Confidence is per claim, never per document: CONFIRMED · 🟡 PROBABLE · HYPOTHESIS · REFUTED. A withdrawn result is kept with its reasoning rather than deleted — that is why the numbers here can be trusted.

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