Two defensive hardenings from the post-fix audit (vs FFmpeg/GStreamer):
1. Move the `pes.discontinuity` partial-drop ABOVE the empty-data guard in
all three audio parsers (ac3/dts/truehd), so a discontinuity signal can
never be stranded by an empty post-gap PES. The demuxer only emits
non-empty PES today; this is defense-in-depth for any future caller.
2. A PES with no PTS must not reset the timeline to 0. ac3 now carries
`flush_pts_ns`, dts continues from the most recent known base; truehd
already kept its running cadence on a None PTS. Matches OSS behavior
(PTS rebases off the next PES that actually carries a PTS).
Adds an ac3 regression test (empty-payload discontinuity PES still drops
the stranded partial). Loss accounting was reviewed: TS-demux CC-gaps are
NOT counted toward lost_video_secs / abort (that is sector-based via
DiscStream::errors / mapfile bytes_unreadable), so a source splice never
inflates loss — no gating needed there.
The AC-3, DTS and TrueHD parsers buffer access units across PES
boundaries. At a concealed-loss gap the buffered unit is truncated:
splicing post-gap bytes onto it manufactures a corrupt frame on top of
the real loss (FFmpeg "Failed to decode block code(s)" / "Invalid data
found" at the gap) and, for TrueHD, strands the PTS cadence into the
non-monotonic audio-DTS band seen on multi-clip titles.
The video parsers already handle this via the ResyncGate, but the
discontinuity signal was only wired into video — audio parsers ignored
pes.discontinuity and spliced across the gap.
Now, when pes.discontinuity is set, each audio parser drops the partial
(clears buf, and for DTS its PTS marks / pending base) so the post-gap
PES re-bases a fresh unit. A lost gap degrades to a clean single-frame
drop instead of a corrupt spliced frame. No effect on perfect rips: the
branch only runs when concealment inserted a discontinuity marker.
Adds a per-parser test feeding a partial frame then a discontinuity PES,
asserting the truncated partial is dropped (not spliced) and the post-gap
PTS is adopted.
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.
TrueHD: when the PES PTS lags the access-unit cadence, resync to the PTS
but never snap the running timestamp backward, so the emitted DTS stays
monotonic across the resync (next_pts_ns = max(next_pts_ns, pts)).
DTS-HD MA: size each EXSS extension substream exactly from its header
(exss_frame_size) and skip it as a unit, so a false 0x7FFE8001 core sync
inside the lossless extension payload can no longer split the access unit
and truncate the extension. Falls back to a bounded scan when the header
is unparseable.
Provenance: build.rs bakes the git short hash into GIT_SUFFIX; the muxing/
writing-application field and the FVI generator tag now record the exact
build (e.g. "freemkv 1.1.0-beta.1 (g835cc99)"), so any output file is
traceable to the revision that produced it.
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.
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.
Add a precommit fixture proving Disc::read_aacs_inputs reads a Long-AD,
multi-extent /AACS/Unit_Key_RO.inf in full — the exact input the online
key-request path depends on (no disc/deploy needed). Make
read_aacs_inputs_from_reader pub(crate) for the test.
Reword internal comments/doc examples to generic descriptions instead of
specific media titles.
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.
When two access units flushed in one parse() call (a core arriving in an
earlier PES than the PES that closes the unit, the standard DTS-HD MA
core+extension-as-separate-PES layout), the second AU inherited the
latest PES's PTS instead of its own core's.
Track per-PES PTS markers keyed by buffer offset and stamp each emitted
AU with the PTS of the PES covering its first byte, rebasing markers on
every front drain. Each AU now keeps its own core's timestamp.
Extends two_cores_back_to_back to assert PTS; adds cross-PES coverage.
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.
DTS-HD MA/HRA access units on Blu-ray are a DTS core frame (sync
0x7FFE8001) followed by one or more DTS extension substreams (sync
0x64582025) carrying the lossless audio. Ground-truthing the Dunkirk
ISO showed the m2ts demuxer hands these out as SEPARATE PES packets on
the same PID: one core PES (exactly core-sized, nothing trailing), then
the extension substreams in following PES packets with their own later
PTS.
The old DtsParser emitted one frame per PES the moment a core frame was
complete, and dropped any PES with no core sync. So every core became a
core-only (lossy) frame and the extension PES packets were discarded as
junk -- silently downgrading the track to lossy DTS core (1557 kb/s CBR,
16-bit) instead of DTS-HD MA (VBR, 24-bit lossless).
Rewrite the parser to assemble across PES boundaries: an access unit
runs from its core sync up to (but not including) the NEXT core sync, so
the core plus every following extension substream stays together. Add a
CodecParser::flush() (default empty) called at end-of-stream by both the
pipelined and inline DiscStream mux paths to drain the final buffered
unit. A 64 KiB cap guarantees forward progress and never stalls if a
boundary can't be found.
Validated on the rip1 testbed: Dunkirk eng+ger and Fight Club eng main
audio now ffprobe as profile=DTS-HD MA (Fight Club eng at 24-bit), with
VBR packet sizes (~2716-2788 B) well above the old fixed 2012 B lossy
core. Genuinely-lossy DTS dub tracks are left untouched.
The DTS parser emitted a core-only frame and discarded the trailing
DTS-HD extension substream whenever the extension straddled a PES
boundary (it advanced past only the core, then re-synced on the core
syncword, skipping the leftover extension bytes). That silently
downgrades DTS-HD MA / HRA to lossy DTS core.
Now: when an extension sync is visible after the core — full, or a
partial prefix at the buffer edge — wait for the full extension instead
of splitting it off; only 'nothing after the core' (final unit / EOF,
no parser flush) is taken as a genuine lossy core-only unit. Adds a
boundary-split regression test asserting core+extension is preserved.
- 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.
- DTS: buffer with core sync detection + frame size from header
- TrueHD: buffer with unit length field parsing
- Same pattern as AC3 fix: incomplete frames held for next PES
- When PES boundaries align (normal case), buffering is a no-op
Matthew Jackson