Commit Graph

4 Commits

Author SHA1 Message Date
sylph-decoder
ac1b76ee39 re: run 'grep the corpus for the claim' on this corpus -- four still standing
Applying my own METHOD entry one iteration after writing it found four refuted
statements still asserted unmarked where a reader lands:

  * envelope correlation 'has no resolving power' -- in three places including
    HANDOFF. The port controlled the same estimator on a single track and got
    r=1.0000 at zero offset; the saturation needs CONCURRENT streams sharing
    timing. I agreed to this in a message and never landed it.
  * '8 of 10 three-chunk regions' -- still asserted in HANDOFF in a different
    section from its own correction.
  * 'r9 is a wild pointer, never a guest address' -- still asserted inside the
    kept-for-the-record section.
  * the ALSA channel permutation, stated without scope, when a later capture
    measured the identity and labelling from it put the silent channel on the
    wrong name.

All four marked in place, striking the sentence and pointing forward.

Two lessons added: a 'kept for the record' section still asserts, so labelling
the heading is not enough; and naming a refuted claim keeps it greppable, so the
audit returns its own corrections as hits and every hit needs reading.

The first item is the one worth admitting: I acknowledged that correction in a
message, wrote the entry about corrections that never land, and then did not land
my own for a full iteration.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01Wuu56cE8vJGTBtn1ppsk8v
2026-08-30 10:35:27 +00:00
sylph-decoder
3e8235ddbd re: resolve_movie_voice_region starts INSIDE the first stream, 8 of 10 multichannel regions
Found because the port refused to apply my stream assignment and did the
arithmetic instead: the running decoder's three ADV contexts sum to 3 584 000 B
against a resolved region of 3 114 352 -- 15 % too small to hold them. Two spans,
one wrong, and it was the disc side.

The gap is 238 packets exactly (487 424 B), which is what a start offset looks
like; ctx0 declares 632 packets and the resolver's leading chunk has 394.

Verified against the decoder's own byte_sizes, which cannot be fitted to: at
-238 packets to_xma_riffs yields [1294336, 1118208, 1171456], all three exactly.
It is a real boundary and not the end of a sweep -- at -300 the previous asset's
chunks appear while the three ADV sizes stay stable.

Disc-wide: 24 of 24 single-chunk regions start at a boundary; 8 of 10 three-chunk
regions start mid-stream. The defect is specific to the multichannel case.

The audit's per-movie number is an UPPER BOUND, not the clip -- its stopping rule
is the chunk count changing, and to_xma_riffs absorbs a few packets of the
previous asset first (243 reported for ADV against a true 238). Only ADV has
external ground truth.

Consequence: in those 8 movies the leading chunk is a truncated first stream, not
a spurious artefact, and anything measured on it was measured on a fragment --
including this corpus's own chunk-0 level, though the assignment survives because
its ratio test was chosen to be immune to the clipping.

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.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01Wuu56cE8vJGTBtn1ppsk8v
2026-08-30 08:41:22 +00:00
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
sylph-decoder
232ae0fa9c re: ask #4 answered -- the intro is a 5.1 WMAPro bed at 0.600 plus three streams
ADV.wmv carries ONE audio stream and it is wmapro 5.1, not XMA. Any framing of
the intro's audio as only 'which of three voice streams to ship' was missing the
bed.

Aligned the 148 s capture against that track (envelope r 0.769 against a median
of -0.001, refined to +224 samples, r 0.900) and solved
capture = g x movie + residual per channel.

The gain is 0.600 on every channel -- a uniform -4.44 dB, a mixer setting rather
than a fit artefact. LFE reproduces to -115.73 dBFS, 72 dB down, which is what
rules out codec difference as the explanation for the other residuals. FC is the
exception: the movie explains NOTHING of it (-0.09 dB), and the movie's own FC is
91.6 % silent.

The residual is three signals, not one: a front pair (r 0.918), a rear pair
(r 0.929), and a centre whose partner LFE is empty. The FC residual spans 34 dB
across 100 ms frames -- bursty, not steady noise.

That CONFIRMS the corpus's 5.1 reading, which voice-three-streams-are-concurrent
recorded as not established, and it confirms the specific detail it offered: that
the mono-in-stereo stream is 'a centre paired with a silent LFE'. Measured from
the output with no access to the stream contents.

Also corrects my own census page: it labelled channels with the ALSA permutation
[0,1,4,5,2,3] from the recipe page, which does NOT apply to this capture. The
6x6 matrix was computed assuming no order, every row's max falls on a distinct
movie channel, and the answer is the identity -- so the census's 'BR is 82 %
silent' was really LFE, reconciling with the movie's own 80.64 % silent LFE.

Reach: one boot, one movie; which XMA context is front/centre/rear is not
determined, only that the residual occupies those positions; and whether 0.600 is
a fixed constant or a volume setting is unknown.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01Wuu56cE8vJGTBtn1ppsk8v
2026-08-30 08:19:03 +00:00