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handoff: tell the port its refusal found a decoder defect, and what is safe to use

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Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01Wuu56cE8vJGTBtn1ppsk8v
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sylph-decoder
2026-08-30 08:41:38 +00:00
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@@ -2529,6 +2529,44 @@ whatever it returns — the same reason a truncated log and a t=0 render both lo
fine from inside. Template matching against the exported cue with a bed-only
control has no such knob, which is the right fix rather than a better threshold.
## 🔴 2026-08-30 — you were right to refuse the weights. The DISC SIDE was wrong.
**Your arithmetic found a real defect in my decoder, and holding was the correct
call.** `resolve_movie_voice_region` starts **inside** the first stream.
| | |
|---|---|
| `ctx0` declares | 632 packets = 1 294 336 B |
| the resolver's leading chunk | 394 packets = 806 912 B |
| **the region starts late by** | **238 packets = 487 424 B** |
A whole number of packets — a start offset, not corruption. Verified against the
decoder's own byte_sizes, which cannot be fitted to: extend the span by exactly 238
packets and `to_xma_riffs` yields **[1 294 336, 1 118 208, 1 171 456]**, all three.
At −300 the *previous* asset's chunks appear while those three stay stable, so −238
is a real boundary.
**Disc-wide: 24 / 24 single-chunk regions are fine; 8 of 10 three-chunk regions
start mid-stream.** The defect is specific to the multichannel case.
🔴 **So your leading chunk is a truncated first stream, not a spurious tail** — in
`ADV` it is 62 % of ctx0. Any measurement you made *on* it was made on a fragment,
including your r=0.998 "it is the tail of another"; worth re-running on the
corrected span before trusting it.
⚠️ **The resolver is NOT patched.** Why the predecessor cue's trailer lands 238
packets into the next asset is unanswered, and a fix guessed from one movie would be
worse than a documented defect. To extend a span yourself: start − 238×2048 for
`ADV`; for the other seven the exact clip is **unknown** (my audit's number is an
upper bound — it reports 243 for `ADV` where the truth is 238).
✅ **The assignment below still stands**, because its ratio test was chosen to be
immune to the clipping — but chunk 0's absolute level was measured over 62 % of its
stream, so treat the 0.05 dB as luckier than it looks.
[`voice-region-starts-late.md`](../re/structures/voice-region-starts-late.md) ·
[evidence](../re/data/voice-region-start-clip.txt) ·
[disc-wide](../re/data/voice-region-start-audit.txt)
## ✅ 2026-08-30 — ask #4 ANSWERED: ship the movie's own 5.1 track **and** the three streams
**You need both.** `ADV.wmv` carries **one** audio stream and it is **WMA Pro 5.1**