Mac → Windows mic passthrough crackled heavily while the identical
stream was clean on the Linux host. Cause: clients push mic audio in
BURSTS on their own clock (the Mac input tap yields ~two 20 ms Opus
packets every ~42 ms) while the WASAPI render loop pulled a block every
~10 ms device period and greedily drained whatever was queued, padding
the rest with zeros — the queue sat near-empty and most periods
inserted mid-stream silence. The Linux backend has absorbed this since
day one with its priming jitter buffer; the WASAPI loop had none.
Port the same semantics: emit silence until ~48 ms is buffered (covers
the worst inter-burst gap), then play from the cushion (zero-filling
only a momentary shortfall), re-prime only after a genuine full drain
(client went quiet). Queue cap raised 80 → 120 ms for burst headroom;
steady-state added latency ≈ the 48 ms cushion.
Diagnosed live on .173: probe tone recording from CABLE Output proved
the endpoint wiring, then the burst-vs-period math explained the
crackle. Build-verified on Windows; on-glass listen pending.
Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
enricobuehler
547bc250b6