alan
6f7f7ddd6c
The bar turned green after 2 s on a timer even when the microphone delivered nothing. It now turns green only on real audio: RMS above 0.0005, or three consecutive chunks that are not digital silence (the virtual mic emits one stray nonzero chunk right after start, and a Bluetooth headset's floor ramps in from a few LSB). Measured 1.2-1.4 s after the key, within 0.14 s of the first real samples. diagnostics/bluetooth/ records how startup went from ~1.6 s (or never) to ~1.1-1.4 s: a btusb driver bug, two PipeWire bluez5 bugs, a 500 ms WirePlumber switch timeout and an over-broad auto-connect rule. Those fixes are machine level and live outside this repo; the patches, tools and measurements are here. STARTUP-TIME.md is the summary and explains the ~0.9 s hardware floor. Co-Authored-By: Claude Fable 5.1 <noreply@anthropic.com> Claude-Session: https://claude.ai/code/session_01Xoc9DJCViR7dg9eKzzAcfQ
2.8 KiB
How we cut Bluetooth microphone startup time
Measured on a Sony WH-1000XM5 over an Intel AX210, PipeWire 1.6.8, WirePlumber 0.5.17, kernel 7.2.3. Times are after the dictation key press.
| before | after | |
|---|---|---|
| mic link (eSCO) up | 0.7–1.0 s, sometimes never | 0.26–0.49 s |
| first real audio at the daemon | 1.5–1.7 s, or never | 1.06–1.43 s |
| "Listening" in the bar | 2.1 s on a timer, even with no audio | 1.19–1.43 s, only on real audio |
What changed
| Change | Where it lives | Gain |
|---|---|---|
| Daemon indicator: green on real audio only (RMS > 0.0005 or three consecutive non-silent chunks), no timer | daemon/sttd.py |
the bar cannot claim to listen to a dead mic |
| WirePlumber profile-switch timeout 500 ms → 50 ms | ~/.local/share/wireplumber/scripts/device/autoswitch-bluetooth-profile.lua |
link up ~0.45 s sooner |
| A2DP auto-connect rule narrowed to the XM5 | ~/.config/wireplumber/wireplumber.conf.d/bluetooth-a2dp-autoconnect.conf |
no 5 s pages of absent devices at login |
btusb driver patch 0002 |
/usr/lib/modules/<kernel>/updates/btusb.ko |
mic link no longer comes up silent when a page overlaps it |
PipeWire bluez5 patches 0001 + 0003 |
~/.local/lib/spa-0.2/bluez5/ via SPA_PLUGIN_DIR drop-ins |
no stale-error dead takes; back-to-back takes work |
Only the first row is part of this repo. The rest are machine-level and are described, with patches and measurements, in HANDOFF.md.
Why ~0.9 s is the floor
key press
0.00 s ─┬─ daemon starts pw-record on camera-effects-mic
│
│ Camera Effects notices the client (250 ms poll),
│ opens its helper stream, WirePlumber waits 50 ms,
│ then asks BlueZ for the headset profile
│
0.30 s ─┼─ eSCO link up (the headset must leave sniff mode,
│ then the radio sets up the synchronous link: ~0.1 s)
│
│ headset sends encoded digital silence while its own
│ mic path starts and mSBC syncs: ~0.5–0.6 s
│ (measured at the decoder; Linux cannot shorten it)
│
0.85 s ─┼─ first non-zero samples leave the headset
│ Camera Effects processing + 50 ms chunking
0.90 s ─┴─ first real audio reaches the daemon
What is left on the Linux side is the ~0.25 s before the profile switch is even requested. The daemon could ask for the headset profile itself when capture starts, but the WirePlumber autoswitch script only restores a profile it switched, so the daemon would have to restore A2DP too. Not done.
The headset's silence after link-up and the eSCO setup are hardware. Words
spoken in the first ~0.9 s are lost unless the microphone is already in
hands-free mode, which drops playback to mono, so it is off by default
(warmMic).