Audio and lip sync
The phone's microphone has two possible jobs and can only do one: be the audio you hear, or be a timing reference that aligns the microphone you actually use. Turning one on turns the other off.
The phone as a microphone#
Options → Send phone mic to OBS makes the camera source carry the phone's microphone — a wireless mic, in effect. Off by default, since most streamers use their own mic and align it instead.
A mic row on the Live screen and in the browser panel picks which one:
| Choice | What you get |
|---|---|
| Auto | iOS's default routing — normally the Bottom mic whatever camera is active, since iOS doesn't tie the two together. A headset or Bluetooth mic takes over automatically. |
| Front | The front array, aimed roughly where the front camera looks. |
| Back | The rear mic, aimed at what the rear camera sees. |
The switch is live.
Automatic lip sync#
Video always arrives a little late, so a separate microphone runs early against it — the dubbed-film effect. The usual fix is to guess a delay in OBS and nudge it. LensLink measures it instead.
Setting it up#
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In the source properties
Pick your real microphone under Lip-sync audio source, then enable Automatically delay that audio source… and Auto-calibrate.
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In the app's Options
Turn on Auto lip-sync reference. The phone's mic is now a timing signal only — never played, never recorded, never on your stream.
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Talk for about fifteen seconds
The plugin compares the two streams, measures the offset and corrects it. The Live screen and browser panel show the stage: Measuring sync, then Sync locked.
Once it is locked#
Your microphone's own delay is now known, so the correction keeps tracking the camera's latency by itself — through silence and straight after a reconnect — and recalibrates if you change audio gear mid-stream.
To force a fresh measurement, tap Recalibrate in the sync pill, on the phone or in the browser panel. It's offered only while locked, the one state where it does anything.
| Readout | Meaning |
|---|---|
| Nothing shown | Auto-calibrate isn't running. |
| Measuring sync | Keep talking. |
| Sync locked | Offset applied and tracked. |
| Recalibrating | Re-measuring after a change. Not an error. |
When your microphone is the slow one#
Some USB interfaces add enough latency that the mic arrives after the video, where delaying it further can't help. Auto video delay for slow mics delays the video instead.
A fixed correction, without auto-calibrate#
With Auto-calibrate off, the delay checkbox alone shifts your mic by the measured camera latency. A known device delay goes in Audio device's own latency and is subtracted.
Why not just type a number in OBS? Camera latency isn't a constant — it moves with resolution, codec, link and network. A measured offset survives switching from 1080p60 Wi-Fi to 4K30 USB. A typed one doesn't.
Screen-mirror audio#
The LensLink Screen source carries real, playable app and system audio — not a timing reference. iOS mutes DRM apps during a broadcast, and your microphone isn't included: screen mirroring.