Round-6 findings from the 10-phase release audit:
- Wire the documented MAX_PENDING_BYTES byte cap into the MPEG-2 GOP
buffer (it was dead code) and add an equivalent MAX_GOP_BYTES cap to the
sparse-PTS reorder, so a crafted stream of few-but-huge access units
cannot over-allocate — both were bounded only by frame count before.
- probe_evo_streams defaulted an unsniffable HD-DVD video stream to H.264,
which mis-parses a VC-1 (or still-encrypted) clip into a corrupt track.
Emit the video stream only when the codec is actually identified — the
honest outcome, matching the audio path (a real clear clip always carries
its sequence header at the head).
- Resume the AU-opener search from a cursor (like the boundary search), so
a long unsynced junk run is O(bytes), not O(buffer) per push.
- Mark mpeg2's now-dead MAX_AU_BUFFER test-only; restore #[doc(hidden)] on
the aacs probe harness module.
- Add regression tests: the 0xFD video-routing guard, the FMTS-is-UHD key
state, and the GOP byte caps.
Round-4 findings from the 10-phase release audit (the first fully clean
round; it dug into the new #22/#18 refactor code):
- AuAssembler closed each AU from only the FRONT mark's fields, so when
one PES fragment carried the source and a later fragment of the same AU
carried the PTS, the second field was dropped — a regression vs the old
separate pts/source mark deques. Now merge the first Some of each field
across all in-range marks.
- parse_vti_clip_order picked the largest residue bucket with
HashMap::into_values().max_by_key(), nondeterministic on a size tie
(randomized HashMap iteration) — could select a different clip table
run-to-run. Break ties by smallest offset.
- Bound the marks/disc_marks deques (MAX_MARKS): the buf-size cap prunes
marks only when bytes accumulate, so a run of zero-length timed
fragments could grow them without bound on hostile input.
- Add push_owned so the PS path moves the PES payload into a passthrough
AU with no copy (MPEG-2 video + all audio), removing a per-PES
malloc+memcpy the refactor had introduced on the DVD path.
- Back-patch the MKV duration from the block END (start + its own
duration) so it covers the final frame instead of understating by one.
- Add direct tests for the MKB record-framing walker; drop a stale
drain_complete_aus doc comment left on process_au.
The MPEG-2 parser hand-rolled its own PES reassembly — a byte buffer plus
parallel PTS / source / discontinuity mark queues keyed by absolute
offset — duplicating what AuAssembler already does for H.264/HEVC/VC-1.
Add a Mode::Mpeg2 to AuAssembler (picture 0x00 with preceding sequence
0xB3 / GOP 0xB8 headers — the same headers-precede-picture shape as the
VC-1 mode) and have the MPEG-2 parser own one via AuAssembler::mpeg2().
parse() now feeds fragments to the assembler and processes each complete
access unit; the buffer, base offset, and three mark queues are gone. The
GOP-buffered temporal_reference reorder and PTS origin-locking are
unchanged. The parser's external contract is unchanged, so all existing
MPEG-2 parser tests pass as-is; new AuAssembler tests cover the MPEG-2
boundary rule directly.
Closes the three residual holes where a concealed/lost gap could still let
a dangling-reference frame reach the muxer (degraded/undecryptable-disc
path only; clean rips are byte-identical and untouched). Root cause: the
discontinuity signal was reconstructed from the 4-bit continuity counter
and applied per-PES, both of which are lossy.
Three coordinated changes:
1. CC-INDEPENDENT marker. fill_null_ts_unit now tags its NULL packets with
an adaptation-field discontinuity_indicator; the demuxer recognises a
0x1FFF packet carrying it as a concealed gap and forces a discontinuity
on every tracked PID (the lost unit's PID is unknowable). This survives
a loss that is an exact multiple of 16 packets (CC aliases to in-sequence
— hole 3) and a loss at a PID's very start (no prior CC — hole 4); it
also drops any open, potentially-truncated partial PES.
2. PUSI ATTRIBUTION. A gap landing on a PES boundary now flags the PES
STARTING after it, not the one flushed at the boundary (hole 1) —
stamping the pre-gap frame could arm-then-disarm the gate on a keyframe
and admit the real post-gap inter frame.
3. PER-FRAME signal. codec::Frame gains `discontinuity`; each parser
propagates it onto the first post-gap frame. MPEG-2 buffers whole GOPs
asynchronously, so it associates the gap by ES OFFSET (like PTS/source),
landing it on the exact post-gap picture mid-GOP (hole 2) — a per-PES
flag stamped the previous picture. consume_ts (and the EOF flush drain)
gate on frame.discontinuity.
Tests: CC-independent marker with in-sequence CC + leading-loss; PUSI
attribution flags the post-gap PES; MPEG-2 offset-mark stamps the post-gap
picture through GOP reorder, not the previous one. Existing B1 gate + EOF
tests still green (2270 lib tests).
Pairs with A2 (read-path NULL-TS concealment). When the demux assembler
sees a TS continuity gap it now stamps `discontinuity` on the next
completed PES; the codec-parse stage carries that onto a per-track
ResyncGate. After a gap on an inter-coded video track the gate drops
forward to the next IRAP/IDR keyframe so no frame with a dangling
reference reaches the muxer (an ffmpeg deep scan would otherwise report
a missing-reference / non-existing-PPS error). Audio and subtitle tracks
have no cross-frame references, so the gate is a no-op there.
- ts.rs: PesPacket gains `discontinuity`; PesAssembler tracks a sticky
pending_discontinuity flag set on CC gap / discontinuity_indicator and
carried to the next completed/flushed PES.
- resync.rs (new): ResyncGate — per-track arm-on-gap, drop non-keyframes
until the next keyframe disarms and resumes. Logs the resync + drop
count once at the keyframe.
- pipelined_stream.rs: precompute per-track is_video, apply the gate in
consume_ts. Out-of-range track index emits as-is (defensive).
Tests: ResyncGate unit tests; ts.rs gap-stamps-discontinuity; end-to-end
B1 video-drops-to-keyframe and audio-never-drops through PipelinedPesStream.
Carry per-picture truth and byte-exact source provenance THROUGH the stream so
the muxer (and the upcoming video index) read MEASURED facts instead of
assuming them. Honest data in, honest data out.
- codec/coding.rs: codec-agnostic PictureInfo (CodingType / FieldOrder + the
accessors field_order/coding_type/nb_fields/progressive/keyframe). Each codec
folds its raw signals in; consumers use only accessors, never branch on codec.
- mpeg2: builds PictureInfo from the picture coding extension and carries it +
SourcePos (source_marks, parallel to pts_marks) on every emitted frame.
- pes / codec::Frame: additive `coding` + `source`, forwarded through the
highway; None for audio/subtitle and the network/stdio deserialize hop.
- mkvstream: DEFER muxer construction until the first coded picture, set the
video track's FieldOrder from the MEASURED value, THEN write the header —
right the first time, no guess, no seek-back. An interlaced track that arrives
with no measured order is LOGGED loudly and left UNDETERMINED, never faked.
- mkv: MkvTrack::video no longer guesses TFF (a bitstream property the scan
cannot know is UNDETERMINED at build). Removed VideoStream::top_field_first
(the dead scan-time guess) crate-wide.
- Tests: parser population (every PictureInfo facet + per-PES source carry) and
mux-stream consumption (measured -> correct; missing -> UNDETERMINED, not
faked). Two obsolete tests updated only after confirming (their own comments)
they existed to enforce the deleted hardcoded-TFF.
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.
Test-hardening release, no runtime changes. Adds spec-grounded unit tests
across the silent-corruption surfaces — UDF/MPLS/CLPI/IFO parsing, BD/DVD
title + extent assembly, AACS/CSS key handling, TS/PS demux + codec parsers,
MKV/EBML container output, the mux pipeline, sector prefetch + decrypt
decorator, drive/SCSI sense decoding, label extraction, and core I/O. Each
test is grounded in the format spec or real on-disc behavior and verified to
fail under a targeted source mutation. No behavior changed.
Library-wide review-and-fix pass: tightened AACS keydb/handshake/variant
handling and trailing-partial-unit policy, corrected MPLS mark offset and
added UDF allocation bounds, hardened the mux/codec framing and M2TS paths,
guarded SCSI READ CAPACITY short transfers and unified error mapping, added
overflow guards on untrusted disc input, and made prefetch shutdown
deterministic. Release profile now builds with thin LTO + single codegen unit.
The video codec parsers (HEVC, H.264, VC-1, MPEG-2) used
pes.dts.or(pes.pts) as each frame's timestamp. MKV block timecodes
are presentation timestamps; frames are stored in decode order and
the player reorders for display by timecode. Using DTS makes the
timecode monotonic in storage order, presenting B-frames in decode
order — visible motion judder / wrong frames on playback, and
PTS-based seeking lands on the wrong frame.
The compressed video was always byte-correct (verified by NAL-level
diff against a known-good demux); this was purely a timestamp defect
affecting every B-frame title. Fix: prefer PTS (pes.pts.or(pes.dts)).
Verified on a real UHD iso->mkv: emitted PTS now reorders for
B-frames identically to a reference muxer.
Update the two tests that asserted the old DTS-preferred behavior and
add an HEVC regression test pinning PTS as the block timecode.
Audit-driven fixes (rounds 1–3):
- hevc: correct hvcC profile/level SPS offsets (HEVC has a 2-byte NAL header)
- mkv: map all DTS variants to the registered A_DTS codec id; force a new
cluster before the i16 cluster-relative timestamp can overflow
- ebml/mkvstream: bound untrusted EBML sizes (no multi-GB allocs); reject
uint>8 (was an OOB panic) and non-{0,4,8} float widths (were a desync)
- ts: skip PES-header bytes that span a TS packet boundary; add the PMT
section_len/prog_info_len bounds the PAT parser already had
- ac3: preserve a 0x0B77 syncword split across a PES boundary; cap buffer
- dts: validate each next-core boundary by decoded core size (a 0x7FFE8001
pattern inside XLL payload no longer false-splits/drops the lossless
extension); reject sub-minimum core frames; fix forced-emit PTS base
- lpcm: DVD program-stream PCM no longer double-strips the BD LPCM header
- vc1/mpeg2: do not emit a parameter-set-only PES as a standalone frame
- pgs/truehd: cap the pending reassembly buffer (parity with ac3/dts)
- aacs: ts_syncs_intact uses the exact packet count
- prefetched: capacity-guard the recycled-buffer set_len
- Cargo.toml: exclude project docs from the published crate
Convergence: a third independent audit pass found no remaining material
(CRITICAL/HIGH/MEDIUM) issues. Full precommit (fmt + clippy -D + tests,
Rust 1.86) green.
- MkvTrack::audio emits A_DTS/MA, A_DTS/HR, A_DTS per the DTS family
instead of mislabelling everything as A_DTS. Plex transcoder and
strict hardware decoders reject DTS-HD MA payload under a plain
A_DTS track.
- PgsParser is now stateful: pairs display PCS with the following
empty PCS to compute a duration. Frame::duration_ns + PesFrame::duration_ns
carry it through; MkvMuxer::write_frame gains a final Option<u64>
parameter that emits BlockGroup + BlockDuration when set. Fixes
subtitle bitmaps lingering past their intended end-time.
Matthew Jackson