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
54fa940591