The wire half of sub-frame slice output (latency §7 LN1, planning
design/nvenc-subframe-slice-output.md Phase 2): toward a client that
advertises the new cap bit (0x20), a chunked-poll encoder session ships each
AU's completed FEC blocks while the tail of the frame is still encoding —
the AU's last packet leaves the host as the encode finishes instead of
after it.
Wire semantics (negotiated; zero change for anyone else):
- Non-final blocks ride SENTINEL headers: block_count = 0 (a value no legacy
sender emits) + frame_bytes = 0 + exactly max_data_per_block data shards,
so the receiver's shard-offset formula needs no total.
- The final block's headers carry the real frame_bytes/block_count (+
FLAG_EOF) and RETRO-VALIDATE the whole frame: totals under which a
received sentinel block is out of range or not full-K kill the frame
wholesale (no spliced delivery) and the index can't be resurrected.
- Firewall: sentinels are bounded by the negotiated limits (full-K exactly,
never the last block the limits allow, no total to lie about); the exact
derived-geometry check runs unchanged on every non-sentinel packet and
retroactively at pinning. Sentinel opens commit a max_frame_bytes buffer,
bounded by the existing IN_FLIGHT_BUF_FACTOR budget (amplification test).
- Order-agnostic like legacy: a reversed frame (final block first) opens
legacy-shaped and still accepts its sentinels against the pinned totals.
- Small/empty streamed AUs degenerate to byte-identical legacy headers.
Host: Packetizer::{begin,push,finish}_streamed seal full-K blocks (data +
parity per block) as chunks arrive; Session::seal_streamed_* share the
pooled-wire + two-lane seal machinery via the new seal_run; the send thread
paces each flush under the frame's existing deadline (pace_sealed split out
of paced_submit) and runs the whole-AU accounting at the last chunk; the
encode pump forwards poll_chunk output as ChunkMsg when the client has the
cap AND the encoder chunks (re-queried per AU — an escalation falls back
seamlessly). Probes never run mid-AU. PUNKTFUNK_STREAMED_AU=0 = host escape
hatch. Client core ORs the cap into Hello (the shared reassembler carries
the support). Sampled first_slice_us vs encode_us PERF log measures the
overlap; the 0xCF stage-field extension stays a follow-up.
Core tests: streamed round-trip (clean/loss/reorder/duplicate, both orders),
sentinel firewall bounds, lying-final wholesale kill + no-resurrect,
open-amplification budget, header-shape pins. Gates still owed before
default-on: security review pass, loss-harness curve, GameStream smoke
(plane untouched structurally), bitrate A/B.
Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
enricobuehler
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