Four audit rounds each fixed one rule in SeamPlan::place and broke another,
because the question the rules were answering has no answer. Inside a
seamless-branching overlap clip k OUT comes AFTER clip k+1 IN — 57.8s of
overlap on the real fixture table — so a single timestamp is legitimately
inside two clips, and a clip file is not trimmed to its marks, so it also
carries material from before its own IN. No rule over timestamps can say which
clip a frame came from, and each attempt was right for one disc layout and
silently wrong for another: 65s of rewind, 17 minutes stranded, 28 minutes
dropped, 55s refused.
Frames already carry the byte offset they were read from (PesFrame::source,
stamped by the TS demuxer). Clip now carries the byte span its stream occupies
in the title feed, recorded while the extents are gathered. So the clip is a
LOOKUP: the offset falls in exactly one span. There is no decision to get wrong.
Every track of a clip lives in the same stream file and therefore shares one
span, so video, audio and subtitles agree by construction. Divergence between
them — each track guessing separately under its own tolerance — is how audio
and video ended up on different clips and drifted apart in the first place.
spans_trusted gates the whole path: unless the spans tile the feed contiguously
from zero, an offset means nothing and provenance is ignored in favour of the
mark heuristics, which is the 1.6.0 behaviour. A broken map degrades instead of
confidently selecting a wrong clip for every frame. A clip referenced twice
reuses its first span (the bytes are read once) and is still trusted.
Sources that stamp no provenance — a mkv:// remux, the deserialize hop — take
the heuristics, which is what they have always used and where they have always
been right, because they have no overlapping clips to be ambiguous about.
36 timeline tests, six of them new and covering: the overlap case marks cannot
see, all tracks agreeing, out-of-marks material dropped AND counted, a holed
span map, a discontiguous one, a repeated clip, and no provenance at all.
Seven defects in the code the test suite executes least — 913 lines of
disc/mod.rs alone are run by no test at all, which is why this round scoped
from coverage rather than from what previous rounds said they had read.
Disc::scan_image kept its own copy of the crack's extent ordering and fed
crack_key_outcome largest-cell-first. That is the fifth instance in this
audit of a local reimplementation drifting from the canonical one, and the
cost here is a key that does not descramble the feature: picking by sector
count bypasses the capacity gate and can select a different VTS entirely.
The copy is gone — which title comes from the canonical order the scan
already applied, and the extents are handed over in playback order,
exactly as decrypt_keys_for_title does. Its doc records why the duplicate
existed so it cannot grow back.
Resolution::pixels returned 1920x1080 for Unknown. That is the FOURTH
instance of one trap and the other three were in this same file, two of
them fixed hours earlier — without sweeping for siblings, which is the
whole reason this one survived. It now returns (0, 0), and the sweep was
done properly this time: every remaining Unknown arm across the crate is
honest, and the two ColorSpace sites that look like fabrication are
emitting H.273 code point 2, which is the spec's own "unspecified". Two
callers carried local Unknown-to-zero workarounds — precisely the cost of
making callers responsible for a lie — and one is now redundant.
BD-ROM Part 3 code 0xA2 is the lossy secondary DTS stream, not lossless
Master Audio. A test asserted the wrong mapping as intended behaviour, so
correcting the code failed it; the test is deleted with a note pointing at
its replacement. That is a NEW failure mode for this audit: not a test
that cannot fail, but one that locks the defect in. There is no
DtsExpress variant to map to, so it takes the lossy DTS-HD member and the
approximation is documented.
Also: DiscSession::identify could panic through drive_mut once the public
API allows an absent drive — two siblings were converted in an earlier
round and this one was missed; an extent end that added without saturating
where the rest of the crate saturates; a diag reason string restating the
comparator's sort keys and drifting from them, now derived from them; and
a short read that advanced the offset by the full request, silently
skipping the gap. That last one existed twice, in two reads with the same
shape, now merged so they cannot drift apart.
The short-read policy is a judgement call I could not derive from a spec:
no skip_errors is a hard error, with skip_errors zero-fills and charges
the loss. It deliberately does not retry mid-unit, because resuming inside
an AACS aligned unit would trade a silent gap for a silent decrypt
desync — the worse of the two.
Three copies of the same two mappings existed. The canonical accessors
returned 6 channels and 48000 Hz for Unknown; a third copy in diag.rs
returned 0. The honest one was the copy.
A plausible wrong answer is worse than an obvious one. Six channels at
48 kHz is indistinguishable from a real 5.1 track, so every caller became
responsible for remembering to check the variant first — and this crate
walked into exactly that: the json:// sink reported a confident 5.1 for
audio whose neighbouring fields said "unknown". That was fixed at the call
site earlier in this audit; this fixes it at the source.
The accessors now return 0, which is what both in-crate call sites already
coerced Unknown to by hand, so their guards are gone and the behaviour is
unchanged. Zero is also obviously wrong if it ever reaches output, where
six is not.
The diag.rs duplicates are deleted rather than corrected — a fourth copy
would have drifted too. Their only caller was a trace line in the same
file, now on the canonical accessors. Their tests moved across and gained
the Unknown case, which is the point: restoring either fabricated value
fails both.
Found by the round-7 correctness agent while fixing the json:// sink; it
flagged the third copy as out of its scope rather than touching it.
Verified zero callers across all consumer crates AND libfreemkv integration tests:
MUX_APP, Disc::{aacs_disc_hash,encrypted_content_ranges,inject_unit_keys},
locate_ranges, mapfile::{MapEntry,entries}, diag::dump_mkv_track,
DiscStream::{errors,lost_bytes} (read via accessors). Removed the unused mux
DemuxSink/FviSink crate-root re-exports (constructed internally by output() via
the direct module path). Staged demux option variants marked allow(dead_code).
Three Silence-of-the-Lambs (R2 PAL SD-DVD) follow-ups for rc.5.2.
SUB-TASK 1 — Windows Explorer showed 12.5 fps (half) for the 576i25 track.
Root cause: the DefaultDecodedFieldDuration (20 ms field) element rc.5.1
added to "fix" Windows fps did the opposite. With FlagInterlaced=1 +
DefaultDuration=40 ms + DefaultDecodedFieldDuration=20 ms, Explorer halved
to 12.5 fps and MediaInfo flipped to VFR. MakeMKV's correct rip omits the
field-duration element, keeps FlagInterlaced=1 + FieldOrder=TFF +
full-frame DefaultDuration (40 ms), and Explorer shows 25 fps / MediaInfo
CFR. Fix: MkvTrack::video now passes field_duration_ns == 0 so the element
is no longer written; the 1/DefaultDuration = 25 fps signal (the only one
tools trust) is the full-frame value. Interlace signalling (FlagInterlaced,
FieldOrder=TFF) is retained — MediaInfo reads scan type from the MPEG-2 ES
picture coding extension, so it still reports Interlaced / Top Field First.
Tests pin the new TrackEntry elements (element present/absent + values).
SUB-TASK 2 — opening "menu"/still-frame video. Traced the MPEG-2
opening-GOP path; the wrong/last seq header and PTS-floor-to-0 hypotheses
are RULED OUT with file:line evidence: codecPrivate is the FIRST sequence
header (read once at headers-ready, mkvstream.rs:115 + pipelined_stream.rs:289),
DVD VOBU structure guarantees each title opens on seq header + I-frame (no
mid-GOP open), the parser back-anchors leading still-frames to the disc's
real timeline (mpeg2.rs:296-303), and the muxer anchors base on the opening
keyframe's real PTS so the t=0 floor (mkv.rs:963) never corrupts it.
Regression tests pin all three (parser + muxer level).
SUB-TASK 3 — make --log-level 3 self-sufficient (diag.rs + minimal hooks).
(a) dump the ACTUAL MKV TrackEntry elements written per track
(tag=mkv.track: FlagInterlaced, FieldOrder, DefaultDuration, field duration,
Display dims, codecPrivate hex) so Windows-fps-class metadata is verifiable
from a log alone. (b) capture the first ~100 coded frames per track (raw)
to <output>.opening.bin with a per-frame summary line (tag=mkv.opening.frame:
track, key/delta, size, PTS) so opening-GOP/menu issues are diagnosable from
a future log without the disc. Both gated to log-level 3; normal runs open
no side file and record nothing.
CI gate (Rust 1.86): fmt --check, clippy -D warnings, and test --tests all
green.
Fixes the "Silence of the Lambs" R2 PAL wrong-substream rip: the feature's
IFO declares one 5.1 AC-3 stream, but the scan assigned it the on-wire
sub-stream id 0x80 purely by per-codec ordinal (ifo::assign_audio_sub_stream_ids).
On this disc the physical 0x80 carries the 2.0 down-mix and the 5.1 main mix
lives at a different 0x8x sub-stream, so the rip muxed 2.0 while labelling it
"Dolby Digital 5.1" (the acmod fixup in mkv.rs then corrected only the Channels
element, surfacing the mismatch as the "IFO claimed 6 but acmod says 2" warning
— too late to re-route).
New src/disc/dvd_audio_probe.rs probes each physical AC-3 sub-stream's real
channel count from the head of the feature (the acmod/lfeon of its first frame
after the 0x0B77 sync) and re-routes each IFO-declared AC-3 stream onto the
physical sub-stream whose actual channel count matches the declared count,
instead of trusting the ordinal. Wired into both mux demux paths
(DiscStream::new and resolve::build_iso_pipeline) over the decrypting reader,
so it works on CSS discs and the autorip ISO-remux path alike. Bounded
512-sector best-effort read; an empty/unreadable probe degrades to the original
ordinal mapping (no regression on normal discs).
The cell selection is left unchanged: the feature's cell 0 (cat=0x02, 302.4s)
is chapter 1 of the movie (matches MakeMKV's chapter map and 1h53 duration
exactly), so it must NOT be dropped — the perceived "wrong video at the start"
was the wrong 2.0 audio over the opening, the same root cause.
Diagnostics (--log-level 3): new tag=dvd.substream rows dump the ACTUAL acmod
channel count of each physical 0x8x sub-stream read from the VOB, and the
per-cell tag=dvd.cell verdict now spells out the keep/skip reason. With the
existing tag=dvd.aattr (IFO declared sub_id + channels) a bug log alone now
shows whether the ordinal 0x80 really carries the declared layout — no disc
needed to diagnose this class.
expose ac3::find_ac3_sync as pub(crate) for the probe.
- CSS: unlock scrambled-sector reads on enforcing drives via bus-auth
only; classify sense 6F/03 as CSS-locked; early-bail on a fully locked
scan; gate the AACS handshake off DVD discs.
- DVD first-play menu no longer prepended to the feature: read the title
VOBS base from vtstt_vobs (0xC4), not the menu VOBS vtsm_vobs (0xC0).
- Interlaced field-duration (DefaultDecodedFieldDuration) written as a
direct TrackEntry child rather than inside Video, so Windows reports
the correct frame rate.
- Audio channel count read from the AC-3 bitstream; FieldOrder set to
TFF; per-track BPS tags.
- Structured disc diagnostics at --log-level 3; reduced per-operation
log spam.
Matthew Jackson