User report at +67 (.voiceChat mode): playback still 'broken'.
Even with VPIO's Apple-documented session-mode pairing,
its output-side gating chain (echo subtraction + adaptive
noise suppression) chops quiet inter-phoneme content of human
voice. Musicbot signal (loud, ~continuous) survives because it
stays above the gating threshold; speech does not.
Fix: set kAUVoiceIOProperty_BypassVoiceProcessing = 1 on the
unit immediately after EnableIO (before stream format / callbacks
/ initialize). This disables ALL VPIO voice processing \u2014 the
unit becomes effectively a vanilla RemoteIO with mic + speaker
buses. Raw samples pass through both directions.
Trade-off:
* Lost: Apple's hardware AEC + AGC + NS on the mic path. User
reports current capture is clean already, suggesting their
test environment (headset? non-speakerphone?) doesn't need
AEC. If echo loops back when speakerphone is engaged, we'll
re-evaluate \u2014 either re-enable VPIO selectively for
echo-prone routes or ship software AEC (DEC-007).
* Gained: playback is no longer gated. Quiet inter-phoneme
speech content reaches the speaker.
Property setter:
* Constant: kAUVoiceIOProperty_BypassVoiceProcessing = 2100
* Scope: Global, Element: Input (1) per WebRTC's reference iOS
ADM (voice_processing_audio_unit.mm).
* Value: u32 = 1 (= bypass).
* Soft-fail with warn log if the property is rejected on an
exotic iOS version (the unit still works, just with VPIO
defaults).
Build counter 67 -> 68.
EdisonJwa
c16318c86b