Apple mic uplink: the microphone was never in the audio graph, so nothing ever pulled it #94

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enricobuehler merged 2 commits from fix/apple-mic-uplink into main 2026-08-07 14:33:49 +00:00

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Author	SHA1	Message	Date
enricobuehler	d2d5058d0b	fix(client/apple): the mic was never in the graph, so nothing ever pulled it ... ROOT CAUSE, from the reporter's device log: 16:25:49.093 mic capture: 48000 Hz, 1 ch <- tap installed, format fine 16:25:49.235 audio engines joined - voice processing active ... 13 s of session, no errors, and the 10 s silence verdict NEVER fires The engine started clean and the tap was installed against a valid format - so neither the format timing nor the encoder was the fault. The tripwire fires after ten seconds of CAPTURED frames and never fired across a 13-second session: the tap received nothing at all. Because the capture side must be pulled, and only the render graph pulls anything. On the combined engine the input node carried a tap and no connection, so it was not in the graph and nobody drove it: the IO unit came up (the recording indicator lit for a beat, then went out as the input went idle) and not one buffer ever reached the tap. No error, no failed start - a session that quietly sent no microphone. The input now runs through a silent sink into the main mixer, which is what Apple's own voice-processing sample does. outputVolume = 0 because the mic must reach the graph and never the speaker. The split path never needed this - a capture-only engine has the input node AS its graph - so this broke exactly when the combined topology became the default. Verified: swift build (macOS), swift build --triple arm64-apple-ios17.0, swift test 208 passed. Awaiting the reporter's on-device confirmation.	2026-08-07 16:30:29 +02:00
enricobuehler	7e34ca3d5e	fix(client/apple): a session that can't voice-process still sends its microphone ... Field report: mic uplink dead on iOS, iPadOS and macOS alike, while Android on the same host works - so the host and the wire are fine. Two defects in the combined (voice-processing) engine, which became the default on all three Apple platforms a week ago and has never run on a device - CI only runs swift test on macOS, and the loopback test counts datagrams without decoding them. - The tap read the input format before the engine was prepared. Enabling voice processing swaps the engine's IO unit for the VPIO one and renegotiates its formats; until prepare() the input node can still report the pre-swap state, 0 Hz / 0 channels included, which installMicTap correctly refuses as 'no usable input device'. Both topologies now prepare first, so the chain is built against what the voice processor actually emits. - A mic chain that failed on the voice-processed engine took the whole uplink down for the session: that arm fell back to playback ONLY. The sibling failure a few lines above - the voice processor refusing to engage at all - already falls back to the split path, which is a working mic without echo cancellation. Both arms do that now. The mic outranks the AEC. Not reproduced locally (no Punktfunk entries in this Mac's log store, and collecting the device's log needs root), so this is a strong inference plus one proven logic defect rather than a confirmed fix. If it persists, Console filtered to subsystem io.unom.punktfunk / category audio names the stage: 'mic capture: N Hz' then 'audio engines joined' then, 10 s in, either 'mic uplink OK - peak ...' or the SILENCE warning. Follow-up worth doing separately: nothing reports whether the uplink actually opened, so the HUD offers a Mute Microphone button over a session sending nothing. Android gates that on a real micRunning signal.	2026-08-07 16:09:33 +02:00