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re: the voice dialogue is in the CENTRE channel -- measured, not inferred

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The 5.1 reading of a voice cue s three concurrent streams was recorded here as a
hypothesis with counter-evidence attached. It is now answered, by the port
fitting the disc s decoded streams against a clean capture of the game s own
6-channel output, with the instrument controlled first (known-present margin
+0.248, known-absent +0.005).

Speech-band margins put streams 2 and 3 at +0.305 and +0.307 on FC, r = 0.989,
above the known-present control, while stream 1 sits in the noise on every
channel. The low band mirrors it exactly: the movie bed at 0.76 to 0.84 on the
four corners against 0.32 on FC. Dialogue in the centre, bed in the corners.

The hypothesis was right for a reason the file could never have supplied.
ChannelMask reads 0x0002 on all three streams, so the header is not merely
unhelpful, it is actively misleading -- refusing to call it 5.1 from the header
was correct, and the oracle answered what the header could not.

Three limits recorded as the measurer stated them: streams 2 and 3 are
indistinguishable to this instrument, so no rule for choosing between them is
vindicated; the one-of-three-streams warning stands, since nothing says what
streams 1 and 3 contribute; and the reach is 59.7 s of a 137 s movie, one run,
one asset.

Also records the capture that would strengthen it most and why it is not taken:
S00A rather than a longer ADV, because its second full-length stream is digital
silence where ADV s is a 0.60x copy, so a structurally different movie would
agree. Reaching it needs a driven rendered run -- S00A starts about 4.5 s after A
on the save slot -- so it cannot use --gpu=null and will carry the additive
padding.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01QsEPXWVaEpyfudtR6re1Pd
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sylph-decoder
2026-08-29 17:01:26 +00:00
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docs/re/structures/voice-three-streams-are-concurrent.md
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@@ -36,7 +36,56 @@ these three contexts appear in the run.
So the three streams are **simultaneous**, not alternative. A consumer that picks
one is discarding two thirds of what the game mixes.
## 🟡 The obvious reading is 5.1, and it is NOT established
## ✅ ANSWERED 2026-08-29 — the dialogue is in the CENTRE channel
Measured by the port, fitting the disc's decoded streams against a clean capture
of the game's own 6-channel output
([`audio-capture-alsa-file-tee.md`](../audio-capture-alsa-file-tee.md)). Their
instrument was controlled first: known-present margin **+0.248**, known-absent
**+0.005**.
Speech-band correlation margins, by output channel:
| | FL | FR | **FC** | LFE | RL | RR |
|---|---|---|---|---|---|---|
| stream 1 (the leading one) | +.013 | +.006 | +.012 | +.009 | +.012 | +.005 |
| **stream 2** | +.238 | +.171 | **+.305** | +.011 | +.035 | +.006 |
| stream 3 | +.240 | +.173 | **+.307** | +.009 | +.054 | +.006 |
**`r = 0.989` on FC**, above the known-present control. And the low band is the
exact mirror — the movie bed at FL .763 / FR .838 / RL .805 / RR .817 on one
lag, with **FC .317**.
✅ **Dialogue in the centre; bed in the four corners.** So the streams *are* a
multichannel decomposition, which is what the 🟡 below hypothesised — and it was
right for a reason the file could never have supplied. **`ChannelMask` reads
`0x0002` on all three streams**; the header is not merely unhelpful here, it is
actively misleading, and refusing to call it 5.1 from the header was correct.
The oracle answered what the header could not.
⚠️ **Three things this does NOT establish**, stated by the measurer:
1. **Streams 2 and 3 are indistinguishable to this instrument** — +.305 vs
+.307, exactly as expected from stream 3 being 0.60 × stream 2 with the
residual 26.8 dB down. So this does **not** vindicate any rule for picking
between them; only that whichever is picked is the dialogue.
2. 🔴 **The "1 of 3 streams" warning stands.** Nothing here says what streams 1
and 3 contribute to the game's output. What changed is its *character*: from
"one of three, contents unknown" to "the centre-channel dialogue, plus two
streams whose relationship to it is measured and whose role is not".
3. **Reach: 59.7 s of a 137 s movie, one run, one asset.** Stream 1 being
undetectable is *consistent* with it being stream 2's tail and a window that
starts before it — a consistent story, not evidence.
❔ **The capture that would strengthen it most is `S00A`, not a longer `ADV`.**
`S00A`'s second full-length stream is **digital silence** where `ADV`'s is a
0.60 × copy, so if FC still carries dialogue there, a structurally different
movie agrees and the finding stops resting on one asset. ⚠️ Reaching it needs a
**driven, rendered** run — `S00A` starts ~4.5 s after Ⓐ on the save slot
([`movie-binding.md`](../movie-binding.md)) — so it cannot use `--gpu=null`, and
its capture will carry the ~10 % additive padding. Not taken.
## 🟡 The obvious reading was 5.1 — recorded here as it stood before the measurement
Three concurrent **stereo** streams is six channels, and N stereo streams is
exactly how XMA carries multichannel audio on the 360. It would explain a lot at