feat(moq-mux): render identical TS legs with `export ts --sync` by t0ms · Pull Request #5949 · moq-dev/moq

t0ms · 2026-10-19T13:34:29Z

Problem

An SMPTE ST 2022-7 receiver merges two copies of one stream packet by packet, so two moq export ts
processes of one broadcast must write the same packets, continuity counters included. Today they
agree on slot timing and, with clean delivery, on where each packet sits, but each counts continuity
from its own join, and content one leg loses moves every later packet of that PID. The
deterministic TS legs quest asks
for every byte a --sync leg renders to be a function of the objects it holds, the catalog and the
rate alone.

Approach

Fixed lanes (ts::lane::Layout). For a constant rate and the catalog, each position of every
25 ms slot has one owner, on the absolute grid every exporter shares: the PCR first, on a PID of
its own; the PAT and PMT at positions spaced for the system buffer, reserved in every slot; each
audio, verbatim and section PID a lane sized for its codec's largest frame (AAC from its channel
count, MP2 from its top bitrate, AC-3 and E-AC-3 from their largest frames, passed through or not,
Opus from its 510 kb/s ceiling, 225 packets/s for teletext, 80 for other private PES, 40 for
sections); video the rest, up to its Rx; 80 packets/s free for SI; nulls elsewhere. Lanes share a
slot by smooth weighted round-robin, counted from the timeline's start so no slot rounds on its
own. A rate too low for the lanes, or a stream whose declared rate comes to less than a packet a
second, is refused when the tables are built.
Groups re-anchor. A group opens at its lane's first position from its first unit's release
instant (decode time less the unit's drain and the track's send-ahead), and its units follow in
order, none before its own release. Nothing outside a group moves its packets, so a leg that lacks
a group, or joined after it, lays the next one where every other leg does. A group held from its
middle is not placed, and a unit that misses its deadline takes nothing. A Dolby access unit
completed from the last PES belongs to that PES's group.
Groups open where the HRD has the one before. A release assumes a full CPB. An H.264 group
whose first picture carries a buffering period SEI is released later by the time its lane takes to
carry what the CPB really leaves empty, CpbSize - BitRate * initial_cpb_removal_delay / 90000,
but never past that picture's deadline. H.264 C.3 bounds that delay by the time since the previous
picture's final arrival, so a lane faster than BitRate has finished the group before on any leg
that holds it, and a leg that lost it opens at the same place. Other streams keep the release
anchor.
Planned when read. A unit is packetized and given its positions as it is read, so a frame the
jitter buffer later drops still moves its group on. An open GOP's leading pictures that a joiner
cannot decode are planned and decode-clocked too, then dropped as leading, so the frames after them
keep their positions and DTS.
Decode clock by count. A video track whose SPS declares max_num_reorder_frames settles a
frame's decode slot once more frames are held than a picture can follow in output after preceding
them in decode: the depth, or twice it plus one for an H.264 SPS that allows field pictures. The
DTS is the slot less the SPS's delay, capped at the PTS. The timing rule's settling, and its delay
that only grows, depend on everything the leg read before, so a leg that lost a group's tail
mid-pyramid raised its delay for good and laid every later group elsewhere. A cut drops the frames
the clock still holds from the cut group. Without a declared depth, or with one deeper than the 16
frames a decoded picture buffer holds, the export warns and keeps the timing rule.
Counters. Each PID's continuity counter restarts at each group, with discontinuity_indicator
on its first packet; tables number from the absolute grid, and flag a jump; SI sections number
from zero at each emission.
Tables and SI. The PAT and PMT go out on the 500 ms grid, and in a leg's first slot, laid one
slot before its first packet so the tables lead it, numbered as the last repetition. Each
section's first packet carries an adaptation field, whose discontinuity_indicator is set where
the grid jumps, as the PCR's is. SI is sent in the slot of its snapshot's timestamp and repeated on
its own absolute grid, in PID and table order, into the free positions; an emission due while its
PID's last is still queued is skipped. At an export's last flush, SI joins only the slots the
media still runs to.
Send-ahead is at most what the lane fills the decoder buffer in, less a slot.
Placed streams. main carries private PES (teletext, and Dolby audio its descriptors name)
and sections whole, each unit its own group, timestamped at its arrival on the program clock.
Under --sync such a unit goes out whole in its lane, released a slot after its placement because
the PCR runs a slot behind the positions, and due a delay after it, with no send-ahead.
Restarts. A restarted timeline runs on from the last slot unless it moved more than 60 s
either way; then the PCR flags the discontinuity. A leg that stalled has laid the slots it owed,
and its subscription can resume as far behind them as the stall lasted.
Refusals. No constant rate (neither --mux-rate nor the catalog's), --stitch and
--passthrough are refused, and so is an SI entry the catalog adds on the clock's PID.
Stats. stats::Release gains overruns (groups that began behind the one before them, where
legs can differ) and late (packets that reached their slot after it went out); the release-clock
log line carries both, and an overrun logs a warning.
two_legs_render_a_skip_the_same_way becomes the complementary case under --sync, un-ignored;
the quest file is removed, with its links.

Decisions a reviewer may want to revisit:

The HRD anchor, asked as export ts --sync: a group that began behind the one before it lays apart on a leg that lost that earlier group #5864. Without it a group that begins behind the one before, about
12 a minute at 12 Mb/s on the test mux at any multiplex rate, lays apart on a leg that lacks the
earlier group, because video's lane stops at its Rx. With it, an overrun means a source that breaks
its own HRD. A stream without a NAL HRD or a buffering period keeps the release anchor and its
overruns, and so does H.265 until its buffering period is read.
Fixed lanes cost headroom, and video's stops at its Rx: on a 9.95 Mb/s broadcast mux the video
lane is 9.93 Mb/s at 12 Mb/s and 10.59 Mb/s at 16 or 24 Mb/s, for 9.0 Mb/s of video.
Counting holds a frame until twice the depth plus one more have been read on a field-capable
SPS: seven frames, 280 ms, on the test mux, inside the release delay.
With the discard, every stopped leg's release clock re-anchored after the stop and finished 0.58
to 1.93 s behind the unstopped leg, measured before the HRD anchor; without it, one leg in four
did. Not yet understood.
The restart window. Run on, a timeline that moved back less than a minute drops what it holds
before the last slot, as stuffing. With the 2 s back this branch first allowed, a leg stopped
for 3 s resumed about 3 s behind its last slot in three of six loss runs on current main, and
laid those slots again under a PCR that stepped back 2.2 to 2.9 s.
Starting a leg one slot early costs 25 ms at join and two packets per slot of reserved table
positions, about 1% at 12 Mb/s.
The PES header byte the quest saw differ at the skip does not reproduce at current main: its
masked comparison passes with --ignored for both lags. Under --sync the headers are compared
byte for byte.

Impact

Opt in: without --sync nothing changes; every existing test but the skip test the quest names
passes unchanged.
Library: Export::with_sync, and two additive stats::Release fields.
Known limits: a leg that skips an SI revision during a stall diverges on SI until the next one;
a catalog change to the track set or SI keys after the tables are built is out of scope; a
timeline starting at media time zero has no slot before its first, so a leg starting there sends
its first packets before the tables.

Results

Loopback, one relay, a 9.95 Mb/s broadcast mux (H.264 field-coded with a CBR NAL HRD and a
buffering period on every random access point, MP2, AC-3, teletext, three SCTE-35 PIDs, DVB SI)
paced on its PCR, --mux-rate 12000000 --delay 1s, graded from the first common PCR slot, at
59d39cd. The review fixes since change every leg alike, the tables' adaptation field and the
skipped SI emissions, and were not re-run:

Arm	Identity	Continuity (TSDuck)	PCR	Merge
Leg B joins 20 s after A	475,105 equal, 0 differ; content in one leg alone only in the joiner's first 1.2 s	0, 0	≤ 25.07 ms, all within 13 ticks	—
Three legs, A and B each stopped 3 s; six runs	0 differ on every pair in every run	R and merge 0; each stopped leg at most 2, at its own mid-group loss	same, every leg; none steps back	equals R in three runs; in the others R lacks 16 to 76 teletext or AC-3 packets of the first 0.85 s that the merge has

Legs that start together subscribe a few milliseconds apart, and each placed PES is its own group,
so in the first second one leg can hold a PES another lacks. No leg counted an overrun. A stopped
leg counted 4,925 or 5,119 late packets in five of the twelve stops, the content it resumed with
behind its last slot; the unstopped leg counted none. Before this branch's port onto current
main, the same arm at 16 and 24 Mb/s gave the same identity, and the grader's controls hold: no
--sync, 373,098 differ; one byte flipped, exactly 1.

cargo nextest run -p moq-mux: 1,607 pass. The five identity tests fail with --sync off; the two
reordering tests fail with the timing rule in place of the count; the test of legs stopped in turn
fails without the discard; a mocked source whose group ends in a burst overruns once without the
HRD anchor; a grid restarted 3 s behind its last slot jumps back with a 2 s window; a placed PES
under --sync goes out whole, no earlier than its placement. Each review fix has a test that fails
without it: an SI entry added on the clock PID, an SPS declaring 2^20 frames of reordering, a lane
of no packets, SI pushed faster than the free positions carry, the tables after a jump, and an SDT
due in every slot at the end of an export.

Follow-ups

H.265's buffering period SEI, laid out differently, for the same anchor.

(Written by Claude Opus 5.5)

`moq export ts --sync` lays every packet on fixed per-PID lanes of the constant-rate grid and re-anchors each group at its first unit's release instant, so two exports of one broadcast emit the same packets, continuity counters included, wherever both hold the content; what one leg lacks stays stuffing in its positions. Implements quest/m2/ts-hitless.md. Co-authored-by: Claude Opus 5.5 <noreply@anthropic.com>

Under --sync, a video track whose SPS declares max_num_reorder_frames settles each frame's decode slot once more frames are held than a picture can follow in output after preceding them in decode (doubled plus one for a field-capable H.264 SPS), at the SPS's fixed delay, with the DTS capped at the PTS. The timing rule's settling and its delay that only grows depend on everything a leg read before, so a leg that lost a group's tail mid-pyramid raised its delay for good and laid every later group elsewhere. A cut drops the frames the clock still holds from the cut group: they wait on frames that will not come, so the slots they would take are a guess. Without a declared depth the export warns and keeps the timing rule. Co-authored-by: Claude Opus 5.5 <noreply@anthropic.com>

A unit is released as early as a full CPB would need it, so a group that fills its lane late can still be on it when the next group's first unit is released: a leg holding it lays the next group behind, where a leg that lost it does not (an overrun), and the two diverge. An H.264 picture opening a buffering period says how long its HRD holds it before decoding (initial_cpb_removal_delay), so how much of the CPB is empty then. Release that picture as much later as its lane takes to carry that room, never so late that it misses its deadline. The HRD received every earlier picture before its first bit (H.264 C.3), so a lane faster than the HRD's rate has carried the group before on any leg that holds it. The SPS walk keeps the NAL HRD's schedule count and delay length, and a reader takes the delay from the access unit's SEI. A stream without a NAL HRD or a buffering period, and H.265, keep today's release. Co-authored-by: Claude Opus 5.5 <noreply@anthropic.com>

chatgpt-codex-connector · 2026-10-19T13:55:17Z

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coderabbitai · 2026-10-19T14:06:37Z

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Walkthrough

Adds export ts --sync for constant-rate MPEG-TS output. The CLI requires --mux-rate or a catalog constant rate and rejects --stitch and --passthrough. The exporter places packets in fixed PID lanes, plans output using group and timing data, and reports overrun and late-packet statistics. H.264 HRD buffering metadata and counted decode timing support synchronized scheduling. Tests cover packet placement, missing content, reordered video, timing boundaries, and invalid configurations.

Priority: ➖ Normal

Merge Risk: 🔵 Low · up to 79ae7

The synchronized-export termination test does not confirm that the stream ends. This is worth strengthening, but no production failure is established, so the change remains mergeable with follow-up.

Pre-merge checks: 5

Check name	Status	Explanation
Title check		The title clearly and concisely describes the main change: synchronized MPEG-TS rendering that produces identical TS legs through `export ts --sync`.
Description check		The description directly explains the problem, implementation approach, validation results, impact, and known limits of synchronized MPEG-TS rendering.
Docstring Coverage		Docstring coverage is 87.05% which is sufficient. The required threshold is 80.00%. Docstring coverage is scoped to functions touched by this diff. Analyzed 193 functions across 15 files.
Linked Issues check		Check skipped because no linked issues were found for this pull request.
Out of Scope Changes check		Check skipped because no linked issues were found for this pull request.

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Inline comments:
Review comments at @doc/bin/cli.md:
- Around line 438-439: Reword the TS export description and the --sync help text
so they describe only the TS output and continuity-counter behavior actually
provided, without claiming that TS identity alone forms an SMPTE ST 2022-7 pair.
- Around line 436-438: Update the `export ts --sync` packet-identity claim in
the CLI documentation to state alongside it that identity can differ when a leg
misses an SI revision during a stall or catalog changes alter the track set or
SI keys; keep these limitations with the claim rather than only listing overruns
and undeclared reorder depth.

Review comments at @rs/moq-mux/src/container/ts/schedule.rs:
- Around line 808-810: Update Schedule::is_empty so sync mode considers both the
grid and self.horizon, remaining non-empty while the next grid index has not
advanced past the recorded horizon. Preserve the existing behavior once the grid
index exceeds the horizon or no horizon is recorded.

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doc/bin/cli.md
quest/m2/README.md
quest/m2/hop-aligned-import.md
quest/m2/ts-hitless.md
quest/m2/ts-rtp-egress.md
rs/moq-cli/src/args.rs
rs/moq-cli/src/main.rs
rs/moq-cli/src/subscribe.rs
rs/moq-mux/benches/ts_schedule.rs
rs/moq-mux/src/codec/h264/mod.rs
rs/moq-mux/src/codec/h265/mod.rs
rs/moq-mux/src/codec/video.rs
rs/moq-mux/src/container/decode.rs
rs/moq-mux/src/container/ts/export.rs
rs/moq-mux/src/container/ts/export_timing_test.rs
rs/moq-mux/src/container/ts/lane.rs
rs/moq-mux/src/container/ts/mod.rs
rs/moq-mux/src/container/ts/schedule.rs
rs/moq-mux/src/container/ts/stats.rs

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quest/m2/README.md
quest/m2/ts-hitless.md
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Under --sync the export places packets straight on the grid, so the schedule never recorded a decode-time horizon and stopped the clock once the grid drained: the last PCR came 335 ms before the last decode time. mux_sync now records each placed unit's decode time, and is_empty holds the clock until the grid's next slot passes it. Co-authored-by: Claude Opus 5.5 <noreply@anthropic.com>

Name what a 1+1 pair's legs can still differ in (SI across a revision or a table the catalog adds or drops), and say an ST 2022-7 pair also needs identical RTP framing, which export ts does not write. Co-authored-by: Claude Opus 5.5 <noreply@anthropic.com>

Placed kinds go out from their placement under `--sync` too, as they do without it: a placed unit is released a slot past its placement, since the PCR runs a slot behind the grid's positions, and has the delay to clear its lane. Whole-PES tracks, where teletext and DVB Dolby audio now import, are laid on lanes sized by their descriptors instead of refused. Co-authored-by: Claude Opus 5.5 <noreply@anthropic.com>

A --sync leg that stalls keeps laying the slots it owes, and on current main its subscription can resume at the group it was in, as far behind those slots as the stall lasted. The two-second window then took the resumed content for a new timeline: the grid jumped back and laid the slots again under a PCR that stepped back. A minute either way keeps it on the same timeline, the missed content left as stuffing. Co-authored-by: Claude Opus 5.5 <noreply@anthropic.com>

A grid that runs on after a restart drops what it holds behind the slot it lays. It counted those packets late only when they reached it after it had resumed, so a stopped leg's loss showed in one run and not the next. Count them as they go, and let the stopped-legs test hold a stopped leg's late packets while the clean leg must have none. Co-authored-by: Claude Opus 5.5 <noreply@anthropic.com>

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Inline comments:
Review comments at @rs/moq-cli/src/args.rs:
- Line 1231: Update the --sync help text near the existing 1+1 pair requirement
to state that both legs must use the same multiplex rate, whether supplied via
--mux-rate or the catalog rate.

Review comments at @rs/moq-mux/src/container/ts/export.rs:
- Around line 2431-2448: Update the `update_catalog` SI-collision validation to
include the configured PCR PID when `--sync` is active. Extend the `es_pids`
collection with `self.psi`’s `pcr_pid` before calling
`reject_colliding_si_pids`, while preserving the existing track-PID checks and
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doc/bin/cli.md
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quest/m2/ts-hitless.md
rs/moq-cli/src/args.rs
rs/moq-cli/src/main.rs
rs/moq-cli/src/subscribe.rs
rs/moq-mux/src/codec/video.rs
rs/moq-mux/src/container/ts/export.rs
rs/moq-mux/src/container/ts/export_test.rs
rs/moq-mux/src/container/ts/export_timing_test.rs
rs/moq-mux/src/container/ts/lane.rs
rs/moq-mux/src/container/ts/schedule.rs
rs/moq-mux/src/container/ts/stats.rs

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quest/m2/README.md

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main now carries moq-dev#5849, whose stats::Release holds the release clock's counters. --sync's overruns and late join it: set beside gaps after Release::of, logged on the release-clock line and watched for change there, serialized only when nonzero like the rest, and listed in the stats concept page. Co-authored-by: Claude Opus 5.5 <noreply@anthropic.com>

chatgpt-codex-connector

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chatgpt-codex-connector · 2026-10-21T11:18:56Z

+	/// output order: the depth, or with fields both fields of each pair it counts and the other
+	/// field of the frame's own pair.
+	pub(crate) fn pictures(self) -> usize {
+		let depth = usize::try_from(self.depth).unwrap_or(usize::MAX);


Bound the SPS reorder count before buffering

When --sync receives an H.264 SPS with an enormous max_num_reorder_frames, this conversion applies no codec or level bound before Track::release passes it to pop_counted, so frames remain in DecodeClock until held.len() > depth. Since input backpressure only observes the jitter buffer, a hostile publisher can make the held-frame and slot collections grow indefinitely; reject an impossible depth or cap the count to a validated decoder limit.

AGENTS.md reference: AGENTS.md:L17-L18

Useful? React with 👍 / 👎.

Fixed in 56f45f0. No decoded picture buffer holds more than 16 frames (H.264 A.3.1, HEVC A.4.2), so both sps_reorders now read a deeper max_num_reorder_frames or sps_max_num_reorder_pics as no declaration (Reorder::MAX_DEPTH). The track then takes the path of an SPS without a bitstream restriction: no reorder delay, and under --sync the warning and the timing rule, so nothing is held for the depth. The MKV export reads the same functions and gets the bound too. an_impossible_reorder_depth_is_undeclared builds baseline SPSs declaring 2, 16 and 2^20 frames and fails without the fix.

(Written by Claude Opus 5.5)

chatgpt-codex-connector · 2026-10-21T11:18:57Z

+	pub fn push_si(&mut self, index: u128, packets: &[u8]) {
+		let from = self.layout.first(index);
+		for packet in packets.as_chunks::<{ TsPacket::SIZE }>().0 {
+			self.si.push_back((from, *packet));


Bound SI queued beyond the reserved lane

With --sync, a non-clock SI entry can request a 25 ms repetition interval and contain more packets than the 80 packets/s SI_LANE reserve drains; every due slot appends the complete snapshot here while Grid::lay removes only the available free positions. A remote publisher can therefore make this VecDeque grow without bound by repeatedly publishing valid large sections, eventually exhausting the export process, so admission needs to refuse excess SI or otherwise keep a bounded backlog.

AGENTS.md reference: AGENTS.md:L18-L18

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Fixed in db0ba7d. Grid::push_si now sends none of an emission on a PID whose previous emission is still queued, so the queue holds at most one emission per PID, a copy of what the export already keeps of each entry's snapshot. Whether an emission is skipped depends only on the grid's queue, which legs laying the same slots with the same snapshots hold alike. Each emission numbers from zero and flags its first section, so a skipped one leaves no counter gap. si_the_free_positions_cannot_carry_does_not_pile_up pushes 40 packets every slot, more than the free positions carry; without the fix 77 are queued by the second slot.

(Written by Claude Opus 5.5)

chatgpt-codex-connector · 2026-10-21T11:18:57Z

+			.iter()
+			.map(|&(pid, need)| {
+				let packets = match need {
+					Need::Fixed(packets) => packets,


Reject zero-capacity sync lanes

A --sync MP2 catalog with sampleRate: 0 makes lane_need produce Need::Fixed(0), and this constructor accepts a lane that never owns a position. The first frame then enters Layout::take, whose loop can never fill, pinning the export task and a CPU core on malformed remote input instead of returning an error; reject any computed zero packet rate when building the layout.

AGENTS.md reference: AGENTS.md:L17-L18

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Fixed in db0ba7d: Layout::new refuses any lane that comes to no packets a second, naming its PID, so the export fails when the tables are built instead of spinning in take. That covers MP2 or AAC with sampleRate 0 (Need::Fixed(0)) and video whose declared HRD rate is below a packet a second (Need::Rest(0)). a_lane_of_no_packets_is_refused fails without the fix.

(Written by Claude Opus 5.5)

chatgpt-codex-connector · 2026-10-21T11:18:57Z

+			.values()
+			.map(|track| track.pid)
+			.chain([self.pmt_pid()])
+			.chain(self.si.keys().map(|(pid, _)| *pid))


Reserve the dedicated PCR PID across SI updates

When a sync catalog adds an SI entry after PAT/PMT construction, this PID was chosen using only the SI keys present initially, while the later collision check excludes elementary and PMT PIDs but not psi.pcr_pid. If that update claims the dedicated PID, a multi-packet SI emission leaves a nonzero payload continuity counter and the following PCR-only packet resets it to its fixed zero value, corrupting that PID's continuity; subsequent catalog updates should reject the dedicated PCR PID as already reserved.

AGENTS.md reference: AGENTS.md:L17-L17

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The same collision CodeRabbit raised: fixed in 1a91e9e, with sync_refuses_a_later_si_entry_on_the_clock_pid, which fails without it.

(Written by Claude Opus 5.5)

chatgpt-codex-connector · 2026-10-21T11:18:57Z

+					let counter = match n {
+						0 => emission,
+						n => emission * (self.tables.len() as u128 - 1) + n as u128 - 1,
+					};
+					packet[3] = (packet[3] & 0xf0) | (counter & 0x0f) as u8;


Flag table discontinuities when the grid jumps

When a sync timeline restarts more than the run-on window from the last slot, jump emits PAT/PMT here with continuity counters recomputed from the new absolute index; unless the values happen to align modulo 16, downstream sees a continuity jump. Export::lay flags only the dedicated PCR packet, which does not mark discontinuity on the PAT or PMT PID, so the first table packets after a jump also need a discontinuity indication (or counters continuous from the prior emission).

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Fixed in db0ba7d. The PAT and PMT are now packetized with a one-byte adaptation field on each section's first packet, and Grid::lay sets its discontinuity_indicator exactly where the slot is a jump, the PCR's condition, and clears it elsewhere. Carrying the field on every emission keeps the table packet count, and so the layout's table positions, the same whether or not a slot flags. A timeline's first tables are not flagged: nothing came before them. the_tables_flag_a_jump fails without the fix.

(Written by Claude Opus 5.5)

Under --sync the PCR rides a PID of its own, picked when the tables are built clear of the SI present then. An SI entry a later catalog update adds was checked against the track PIDs alone, so it could land on the clock PID, sharing its continuity counter and flagging a time-base break at each emission. Check it against the PCR PID too. The --sync help and the CLI page now say every leg needs the same rate. Co-authored-by: Claude Opus 5.5 <noreply@anthropic.com>

Co-authored-by: Claude Opus 5.5 <noreply@anthropic.com>

…s on a jump Co-authored-by: Claude Opus 5.5 <noreply@anthropic.com>

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chatgpt-codex-connector · 2026-10-21T13:06:35Z

+				&& known.is_none_or(|known| index < known)
+			{
+				self.queue_si(index)?;


Stop replenishing SI while draining the final grid

When a --sync export has a non-clock SI entry whose interval collapses to one PCR slot, such as 0 or 25 ms, an EOF or generation change calls lay(None). This branch queues SI before Schedule::next can observe an empty grid, so as soon as Grid::lay drains one emission the next iteration adds another; lay never returns and keeps appending TS slots to self.queue until CPU or memory is exhausted. Stop periodic SI admission after the media horizon during this flush while still draining emissions already queued.

AGENTS.md reference: AGENTS.md:L18-L18

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Fixed in 79ae7c9. At the last flush (lay(None)), SI now joins only the slots the media still runs to. Schedule::media_done holds once every media packet placed has gone out and the clock has passed the last decode time; after that no SI is queued, and the emissions already queued still drain, since is_empty waits for them. Guarding on the SI queue alone would not do: two PIDs due every slot would take turns keeping it non-empty.

New test, si_due_every_slot_ends_with_the_media_under_sync: under --sync, an SDT at interval 0 repeats while the media runs, and the export ends. The export runs on a thread of its own, because a flush that never returns blocks the runtime that would time it out. With the old condition, the test fails at its 5 s deadline instead of hanging.

(Written by Claude Opus 5.5)

Co-authored-by: Claude Opus 5.5 <noreply@anthropic.com>

kixelated · 2026-10-21T23:48:39Z

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chatgpt-codex-connector · 2026-10-21T23:55:09Z

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kixelated · 2026-10-21T23:59:39Z

Queueing for merge via /quest-merge.

Reviews: CodeRabbit reviewed up to 79ae7c9 (Low risk) and Codex reviewed db0ba7d. Every CodeRabbit and Codex thread has an answer. The head 75d2e32 only changes a test, si_due_every_slot_ends_with_the_media_under_sync: it now fails when the export stalls instead of ending, which closes CodeRabbit's last nitpick. Codex tried to review 75d2e32 twice and failed both times, so the earlier reviews cover this test-only change.
Merge state: no conflicts with main. Check runs in the merge queue.

(Written by Claude Opus 5.5)

Main's group-end settle (moq-dev#6139) stays off under --sync: the counted decode clock settles each DTS from the frames read, and a cut group's held frames are dropped, so legs stay identical. Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

kixelated · 2026-10-22T04:58:15Z

@codex review

Merged main into the PR. The non-trivial resolution is in rs/moq-mux/src/container/ts/export.rs: main's group-end settle stays off under --sync (it broke legs_stopped_in_turn_stay_complementary), and the PCR PID now takes main's reserved-PID fallback only without sync.

(Written by Claude Opus 5.5)

chatgpt-codex-connector · 2026-10-22T05:07:37Z

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kixelated · 2026-10-22T05:44:25Z

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Retrying after the last attempt failed. Focus on the main merge in 56f0d17, rs/moq-mux/src/container/ts/export.rs: main's group-end settle is off under --sync, and the PCR PID keeps main's reserved-PID fallback only without sync.

(Written by Claude Opus 5.5)

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chatgpt-codex-connector · 2026-10-22T05:49:42Z

-				Poll::Ready(Some(Event::GroupEnd | Event::Cut)) => self.settle = true,
+				// Under sync the frames read settle each DTS, not when this leg found the source
+				// empty, and [`Self::queue`] drops what a cut group left held.
+				Poll::Ready(Some(Event::GroupEnd | Event::Cut)) => self.settle = self.sync.is_none(),


Settle group tails in synchronized exports

When --sync carries reordered video and a group ends with up to the declared reorder depth still in DecodeClock, this assignment suppresses the pending flush. If the next group is missing, its cut counter changes before another picture can settle that tail, so Track::queue calls clock.discard() and drops pictures from the preceding complete group that both legs received; a cut group similarly loses its last delivered pictures. Preserve the GroupEnd/Cut settlement under sync before applying the next group's loss handling.

AGENTS.md reference: rs/moq-mux/AGENTS.md:L5-L5

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Not changing this; the suppression is deliberate and matches the PR's pre-merge behavior under --sync.

A clean end then a missing group drops nothing: Item::GroupEnd clears the source's open flag, so the following Read::Gap adds a skip but no cut (source.rs), held == pending.cut still holds, and the next frames read settle the tail. A closed group's successors all present after it, so they settle the same DTS a flush would.

A cut group's held tail is dropped on purpose. pop_counted takes each DTS from the held window, and a flush without the frames the cut lost gives a DTS a clean leg does not, so the bytes at those positions would differ from another leg's. Dropping leaves stuffing that a leg which received the group fills. legs_stopped_in_turn_stay_complementary covers it and fails with main's settle turned on under sync.

(Written by Claude Opus 5.5)

chatgpt-codex-connector · 2026-10-22T05:49:42Z

+			.map(|track| track.pid)
+			.max()
+			.unwrap_or(FIRST_ES_PID);
+		(top + 1..0x1FFF)


Search all free PIDs for the synchronized PCR

With --sync, a valid catalog whose highest elementary-stream PID is 0x1ffe (or whose SI entries occupy all larger candidate PIDs) always fails here: clock_pid only scans above top, so it reports "no PID left" even when lower IDs such as 0x1001 are unused. The non-sync branch inherited main's full reserved-PID scan, and the synchronized dedicated PCR needs the same all-free-PID fallback so valid sparse or data-only TS layouts remain exportable.

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Fixed in 87d7e7d: clock_pid now wraps to the free PIDs from FIRST_ES_PID below the streams when none is free above them, mirroring the non-sync fallback and staying deterministic across legs. sync_clock_pid_falls_below_the_streams puts the video on 0x1FFE and expects the PCR on 0x1001; without the fix it fails with "no PID left for the PCR".

(Written by Claude Opus 5.5)

Under --sync the dedicated PCR PID was searched only above the highest elementary-stream PID, so a program with a stream on 0x1FFE failed to export though lower PIDs were free. The search now wraps to FIRST_ES_PID, still deterministic across legs. Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

kixelated · 2026-10-22T06:25:53Z

Queueing for merge via /quest-merge.

Codex reviewed the main merge at 56f0d17 and raised two findings:
- The sync PCR PID search found no free PID when a stream sat on 0x1FFE. Fixed in 87d7e7d: the search now wraps below the streams, with a test that fails without the fix.
- Settle group tails under sync: declined, with the reasoning in the thread. A clean group end followed by a missing group drops nothing. A cut group's held tail is dropped on purpose so legs stay complementary, and turning main's settle on under sync fails legs_stopped_in_turn_stay_complementary.
Codex's automatic review of 87d7e7d failed. The only change since its review is that fix, so its review of 56f0d17 covers it.
Every earlier Codex thread has a fix and a test, and all of them still pass after the merge. cargo test -p moq-mux passes (1620 tests) and so do the just check lints.
The PR-level Check run is waiting for fork workflow approval. On main PRs it only reports skipped, and the real gate runs in the merge queue.

(Written by Claude Opus 5.5)

Resolve rs/moq-cli/src/subscribe.rs: keep main's moq_clock::now() and the PR's six-count --sync report tuple. Align quest/m1/ts-reliability/pmt-export.md, which main linked to the ts-hitless quest this PR finishes, by moving that constraint into its plan. Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

kixelated · 2026-10-22T09:58:08Z

Merged main into this branch after the queue dropped it for a conflict with moq-dev/moq#6248 (merge commit 5e5a402, no rebase).

rs/moq-cli/src/subscribe.rs: kept main's moq_clock::now() and this PR's six-count --sync report tuple.
quest/m1/ts-reliability/pmt-export.md: main added a Related link to /quest/m2/ts-hitless.md, which this PR finishes and deletes. Moved that constraint into its plan ("under --sync, the revision is a function of the catalog alone") and dropped the dead link.

Local checks: clippy -D warnings on moq-cli and moq-mux, moq-mux tests, quest check. The announced::tests network tests in moq-cli flaked once each under full parallel load and pass in isolation; this PR does not touch them.

(Written by Claude Opus 5.5)

Resolve against #5949 (TS `--sync` lanes) and #6249 (arrival-stamp lateness): a rebound source restamps `subscribed` instead of the removed `empty`, frames carry their arrival through the splice, and the TS lanes keep reading the source's group sequence. Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

t0ms and others added 3 commits October 19, 2026 14:34

t0ms marked this pull request as ready for review October 19, 2026 13:55

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Comment thread rs/moq-mux/src/container/ts/schedule.rs

t0ms marked this pull request as draft October 19, 2026 14:48

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This was referenced Oct 19, 2026

quest: import ten open issues #5969

Merged

export ts --sync: a group that began behind the one before it lays apart on a leg that lost that earlier group #5864

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t0ms marked this pull request as draft October 20, 2026 11:41

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Comment thread rs/moq-mux/src/container/ts/export.rs

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t0ms and others added 3 commits October 21, 2026 12:21

fix(mux): read a reorder depth past the DPB as undeclared

56f45f0

Co-authored-by: Claude Opus 5.5 <noreply@anthropic.com>

fix(mux): refuse an empty sync lane, skip SI still queued, flag table…

db0ba7d

…s on a jump Co-authored-by: Claude Opus 5.5 <noreply@anthropic.com>

t0ms marked this pull request as draft October 21, 2026 12:51

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t0ms marked this pull request as draft October 21, 2026 13:37

fix(mux): stop admitting SI once the last flush's media is out

79ae7c9

Co-authored-by: Claude Opus 5.5 <noreply@anthropic.com>

t0ms marked this pull request as ready for review October 21, 2026 14:19

t0ms mentioned this pull request Oct 21, 2026

fix(mux): retire TS tracks a PMT revision drops or changes #6208

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kixelated mentioned this pull request Oct 22, 2026

quest: audit the tree against main (2026-10-22) #6273

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kixelated enabled auto-merge October 22, 2026 06:25

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t0ms mentioned this pull request Oct 22, 2026

fix(mux): the TS export follows a PMT revision at the next version #6289

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github-merge-queue Bot removed this pull request from the merge queue due to a conflict with the base branch Oct 22, 2026

kixelated added this pull request to the merge queue Oct 22, 2026

This was referenced Oct 22, 2026

fix(mux): TS programs follow the PAT as it changes #6301

Closed

feat(moq-mux): send synced TS legs as RTP with export ts --rtp #6304

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Merged via the queue into moq-dev:main with commit 2d36911 Oct 22, 2026
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This was referenced Oct 22, 2026

feat(quic)!: bound incomplete messages with receive leases #5878

Merged

fix(mux): run the TS recovery arms clean at a 500 ms delay #6236

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This was referenced Oct 22, 2026

fix(moq-mux): exporters follow a rendition moved to a new track #6276

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refactor(mux)!: remove export ts --sync #6554

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