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Do not call a track forced off one display set of a sample

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A forced verdict is an absence claim, and a sampled run sees a fraction
of a track. Measured on real discs: tracks exist that flag about a
quarter of their display sets and leave the rest unflagged, so a sample
that catches one flagged set and nothing else promotes a full dialogue
track to forced -- which players then force on screen. A sampled run now
needs two display sets; a run that read every extent end to end has no
unread gap and may still promote off one.
This commit is contained in:
Matthew Jackson
2026-08-02 17:05:28 -07:00
parent abffa4235a
commit 17bb13b077
2 changed files with 106 additions and 13 deletions
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CHANGELOG.md
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@@ -24,6 +24,14 @@
them, and an entry only answers for a run that intended to read no more than
it did. Positive evidence (a non-forced display set was seen) still answers
regardless, being irretractable.
- **A forced verdict could rest on a single display set.** Calling a track
forced is an absence claim — "no display set here was un-flagged" — and a
sampled read sees a fraction of a track. Measured on real discs: tracks exist
that carry `forced_on_flag` on about a quarter of their display sets and not
on the rest, so catching one flagged set and nothing else is exactly what a
wrong promotion looks like. A sampled run now needs at least two display sets
before it may assert forced; a run that read every extent end to end has no
unread gap and may still promote off one (single-sign forced tracks exist).
- **Content could never correct a wrong vendor forced label.** The muxer only
ever promoted `FlagForced` 0 → 1, so a track labelled forced stayed forced in
the output even when the mux had seen every one of its two thousand display