From 5df3914160423aba91ae073e0755cdc5fc67593b Mon Sep 17 00:00:00 2001 From: ReaperOfVeriod Date: Sun, 11 Oct 2026 04:06:31 +0200 Subject: [PATCH] Record an unresolved discrepancy in the SBlk record size Range measured: level 0 SBlk, 24..19508, 19484 bytes. The 0x7f/0x47f marker words sit at 12-byte spacing on 144 of roughly 180 occurrences, with 24-byte and larger gaps accounting for the rest. So there is a 12-byte structure. That contradicts the autocorrelation. If records were 12 bytes, stride 12 should peak, and it does not: stride 12 +0.237 stride 20 +0.175 stride 24 +0.237 stride 40 +0.454 stride 48 +0.239 40 is not a multiple of 12, so the measurements disagree rather than one explaining the other. Recorded as open rather than resolved in favour of either: the marker spacing says 12, the period says 40, and 40 being twice as strong is the more surprising of the two. Worth resolving before attempting a record layout, because a layout built on the wrong one will parse plausibly and be wrong. --- docs/formats/core-data-regions.md | 31 +++++++++++++++++++++++++++++++ 1 file changed, 31 insertions(+) diff --git a/docs/formats/core-data-regions.md b/docs/formats/core-data-regions.md index 9c3fc06..ce97e3d 100644 --- a/docs/formats/core-data-regions.md +++ b/docs/formats/core-data-regions.md @@ -565,3 +565,34 @@ one. Neither applies here, and the tiling identity cannot be inflated at all. This is the strongest form of evidence produced in this project: a structural invariant confirmed by two methods that do not share a failure mode. + +## Sound bank SBlk: a 12-byte marker that does not explain the 40-byte period + +**Range measured:** level 0 `SBlk`, 24..19508 (19,484 bytes). + +**Method:** positions of the `0x7f`/`0x47f` marker words, and their spacing. + +**Result:** those markers sit at **12-byte spacing on 144 of roughly 180 +occurrences**, with 24-byte and larger gaps accounting for the rest. So there +is a 12-byte structure in the data. + +**But that contradicts the autocorrelation.** If records were 12 bytes, stride +12 should be the peak. It is not: + +| stride | excess over shuffled | +|---|---| +| 12 | +0.237 | +| 20 | +0.175 | +| 24 | +0.237 | +| **40** | **+0.454** | +| 48 | +0.239 | + +40 is not a multiple of 12, so the two measurements disagree rather than one +explaining the other. Recorded as an open discrepancy rather than resolved in +favour of either: the marker spacing says 12, the period says 40, and 40 being +twice as strong is the more surprising of the two. + +This is the first place in this project where two sound measurements of the +same data point at incompatible answers. Worth resolving before any record +layout is attempted, because a layout built on the wrong one will parse +plausibly and be wrong.