Groundwork for multi-Gbps (2.5G link here, 5G to the Mac Studio). The encoder is
pixel-rate bound, not bitrate bound, so these unblock the transport:
- MAX_BITRATE_KBPS 2G -> 8G, MAX_PROBE_KBPS 3G -> 10G (the cap was policy, not a
hardware limit — NVENC emits multi-Gbps trivially with the 2-way split).
- Welcome shard_payload 1200 -> 1452: fills a 1500 MTU, ~17% fewer packets for
free (even size, FEC-safe; negotiated so the client follows).
- PUNKTFUNK_FEC_PCT env overrides the 20% FEC default — a clean wired LAN can drop
it (every recovery shard is wire bytes+packets); 0 disables FEC.
Next: UDP GSO (the dominant lever — research shows ~2.4x throughput / ~40x fewer
syscalls; sendmmsg batching alone is insufficient) + in-place AES-GCM seal.
Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
enricobuehler
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