rustdesk 7bab2c3297 bump webrtc fork: MTU-safe bundles, a reordering window, tail loss within the RTT ...

rustdesk-org/webrtc cc6633bc, three commits on 825a0a48, all on the path
that sends without a congestion window:

Both bundlers counted a DATA chunk by its payload alone; with the header and
padding counted, bundles of small chunks stay within the MTU, and the fragment
payload rounds down to 1160 so a full chunk does too. A chunk is fast
retransmitted at most five times, KCP's IKCP_FASTACK_LIMIT.

A frame's chunks go out within microseconds of each other, so on a path that
jitters the send-order rule resent every chunk that landed behind three of
its siblings: 2.7x the payload on the wire at 10ms of jitter, and on a link
without the room for that, a queue that fed on itself. A reordering window,
RACK's, makes evidence count only from what was sent a quarter of an srtt
after the chunk once the path is seen to reorder, widening on the duplicate
TSNs the receiver reports. 5 Mbps, 1% loss, 20ms jitter: 600 of 600 frames
at a 98ms mean where 290 arrived at 6.2s.

A chunk lost at the tail of a burst has only T3-rtx, which ran from floors
sized for a 200ms delayed ack and restarted only on the tail's predecessor's
ack: 600ms and more. Every DATA chunk now carries the I bit, the floors are
KCP's shape, and a fast retransmission restarts the timer. One 200-byte
message per frame at 5% loss: 9 of 600 later than 200ms, from 42.

Random loss without jitter is unchanged at every rate and frame size.

Co-Authored-By: Claude Fable 5.1 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_019aokqJuhjvB3kijXtAg5Ns

2026-09-05 22:55:44 +08:00

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