Files
Sylpheed/crates
sylph-decoder 8c71520ab8 re: which ADV stream sits where -- settled by level, not by waveform
Completes ask #4. The three chunks were dumped from the resolved voice region
and decoded; the assignment is ctx0 -> FL/FR, ctx1 -> FC with LFE silent,
ctx2 -> BL/BR.

Two instruments failed first and both look like results, so both are recorded.
Envelope correlation with a per-pair lag search returns 0.86-0.95 for EVERY
chunk against EVERY channel, because all six residual channels share the
dialogue's activity timing -- that is an instrument with no resolving power, not
a finding. Sample-level correlation returns about zero, because the chunks do
not start with the movie and the XMA decode's framing offset is unknown.

Level settles it under the same 0.600 gain the bed uses: each stream lands
within 0.5 dB of exactly one residual pair and misses the others by 4-6 dB. The
ratio test is immune to chunk 0 being a clipped tail of ctx0 -- chunk0 - chunk2
is +5.88 dB against FL - BL at +6.18 dB, agreeing to 0.30 dB, where a swap would
be wrong by 11.76 dB.

Structural confirmation: chunk 1 is the only chunk with a digitally silent
channel and LFE is the only output channel with an empty residual (-115.73
dBFS), one to one; and the internal L/R correlations track the residual pairs'
(0.932 vs 0.918, 0.962 vs 0.929).

Worth having on its own: the same 0.600 scales both the movie bed and the voice,
so it is one mixer gain rather than two.

Reach: levels, not waveforms; one boot, one movie; and whether 0.600 is a fixed
constant or a volume setting is still unknown.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01Wuu56cE8vJGTBtn1ppsk8v
2026-08-30 08:32:14 +00:00
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