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Merged
kixelated merged 1 commit into from
Oct 23, 2026
Merged

quest: pace the gap slots after a short forward restart #6506

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1 change: 1 addition & 0 deletions quest/m2/README.md
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Expand Up @@ -135,6 +135,7 @@ ranked just below deterministic TS legs, which it requires.
- [Deterministic H.265 TS legs](/quest/m2/ts-hitless-h265.md) - H.265's buffering period gets the same group anchor as H.264
- [TS over RTP legs](/quest/m2/ts-rtp-egress.md) - two legs send identical RTP packets, headers included, so an ST 2022-7 receiver can merge them
- [Old tail across a restart](/quest/m2/ts-sync-restart-tail.md) - both `--sync` legs send the old timeline's tail up to a restart, so an ST 2022-7 merge has no hole there
- [Paced gap after a restart](/quest/m2/ts-restart-gap-burst.md) - a forward restart within the minute no longer sends every gap slot in one burst
- [moqsrc A/V sync](/quest/m2/moqsrc-av-sync.md) - a nightly test measures A/V skew from `moqsrc` through clock-synced sinks
- [MP4 export](/quest/m2/mp4-export.md) - `moq export mp4 --output` records crash-safe fragments, then finishes a regular MP4 with moov at the end
- [fMP4 edit lists](/quest/m2/fmp4-edit-lists.md) - the fMP4 importer applies edit lists to frame timestamps
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24 changes: 24 additions & 0 deletions quest/m2/ts-restart-gap-burst.md
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# [S] Pace the gap slots after a short forward restart

## Goal

After a forward timeline restart within the minute a restarted grid runs on
across (`AHEAD` in `rs/moq-mux/src/container/ts/lane.rs`), `moq export ts`
lays every slot in the gap at once. On the new clock their due times are
already past, so a leg sends them in one burst, which can overflow a finite
UDP or sink queue. The plain stdout TS path bursts the same way, and so does
a `--sync --rtp` leg once
[moq-dev/moq#6304](https://github.com/moq-dev/moq/pull/6304) lands. The gap
slots are either paced out or not laid at all.

## Plan

- Decide between pacing the gap slots and skipping them. Skipping must keep
synced legs identical, so it must follow from something both legs read
alike.
- Test with a mocked-time restart inside the minute, asserting datagram or
packet spacing. `an_rtp_leg_sends_its_paced_tail_before_a_restart` from
that PR restarts 120 s ahead specifically to avoid this case, so it is the
natural one to extend.

Public API: none.
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