Bug Report — Live Link Face recording fails when AirPlay screen mirroring is active

General Feedback & Requests
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Title: Live Link Face 1.7.3 — Recording fails with AVFoundationErrorDomain -11800 / NSOSStatusErrorDomain -17771 while AirPlay screen mirroring is active

Summary

Starting a recording (locally, or via OSC /RecordStart) in Live Link Face fails immediately whenever AirPlay screen mirroring is active at the same time (mirroring the iPhone screen to a Windows machine through an AirPlay receiver). The take stops recording right after it starts, and the resulting MOV file is corrupted (no moov atom — duration 0, unplayable). The same recording works fine when AirPlay mirroring is turned off.

This appears to be a regression: version 1.7.1 changelog states “Fixes an issue that prevented recording when AirPlay screen mirroring is active”, but the failure still reproduces on 1.7.3 (latest).

Environment

Item Value
Live Link Face version 1.7.3
iOS version [FILL: e.g. iOS 26.0 — check Settings → General → About]
iPhone model [FILL: e.g. iPhone 15 Pro]
Capture mode [FILL: MetaHuman Animator / Live Link (ARKit)]
Frame rate [FILL: 60 FPS / 30 FPS]
AirPlay receiver (on PC) AirMirror (Windows), acting as an AirPlay receiver
Unreal Engine version [FILL: e.g. 5.7]
Recording trigger [FILL: in-app button / OSC /RecordStart]

Steps to Reproduce

  1. Start AirPlay screen mirroring from the iPhone to the Windows AirPlay receiver (AirMirror).
  2. Open Live Link Face, select the capture mode.
  3. Start a recording (tap the record button, or send /RecordStart slate take via OSC).
  4. Observe: the recording stops almost immediately and an error dialog appears.

Expected Result

The recording should start normally, keep running until stopped, and produce a valid, playable MOV file — even while the screen is being mirrored via AirPlay.

Actual Result

The recording aborts immediately. The following error is shown:

Error Domain=AVFoundationErrorDomain Code=-11800 "The operation could not be completed"
UserInfo={
  NSLocalizedFailureReason=An unknown error occurred (-17771),
  NSLocalizedDescription=The operation could not be completed,
  NSUnderlyingError=<...> {
    Error Domain=NSOSStatusErrorDomain Code=-17771 "(null)"
  }
}

The partial MOV file that is left behind is corrupt: it only contains ftyp and a broken mdat box, with no moov box, so its duration reads as 0 and it cannot be played.

Additional Context / Analysis

  • Turning off AirPlay mirroring before recording makes the error disappear — recording then works normally. This strongly suggests the hardware video encoder session used for AirPlay mirroring conflicts with the encoder session Live Link Face needs to write the camera stream to disk.
  • The underlying error NSOSStatusErrorDomain Code=-17771 is the VideoToolbox / AVAssetWriter reporting that the hardware encoder resource is unavailable at finishWriting.
  • Community reports of the same -11800 failure during AirPlay go back to Live Link Face 1.6.0 (with a similar underlying code -16364). The 1.7.1 fix appears not to cover the current iOS release.

What I’ve Already Tried

  • [x] Updated Live Link Face to the latest version (1.7.3).
  • [x] Confirmed the failure reproduces 100% when AirPlay is active, and never when it is off.
  • [x] Confirmed sufficient free storage on the device (not a disk-full issue).
  • [ ] (check what else you tried: 30 FPS, disabling Live Link streaming, restarting the device, etc.)

Attachments

  • Screenshot of the error dialog (attached).