CameraKit crashes if on audio call (iOS)

aidan

**Tested with Discord and FaceTime - if I have an active call going it messes with the AVCaptureSession/ARKit somehow and causes CameraKit to fail crashing the whole app

If I set AVSessionInput.audioEnabled to False it at least doesn't crash anymore:
avSession = AVSessionInput(session: self.captureSession) avSession!.audioEnabled = false

BUT the camera still freezes up due to something wrong with the ARSession:

2023-04-08 04:00:13.437839-0400 Gotcha[1259:72917] [Session] ARSession <0x13f250d00>: did fail with error: Error Domain=com.apple.arkit.error Code=102 "Required sensor failed." UserInfo={NSLocalizedFailureReason=A sensor failed to deliver the required input., NSUnderlyingError=0x2808bcc00 {Error Domain=AVFoundationErrorDomain Code=-11800 "The operation could not be completed" UserInfo={NSLocalizedFailureReason=An unknown error occurred (-12780), NSLocalizedDescription=The operation could not be completed, NSUnderlyingError=0x2809c8b40 {Error Domain=NSOSStatusErrorDomain Code=-12780 "(null)"}}}, NSLocalizedRecoverySuggestion=Make sure that the application has the required privacy settings., NSLocalizedDescription=Required sensor failed.}

Only happens when on call! Very strange behavior.

aidan

Update: The error doesn't seem to have anything to do with Microphone or Video usage in other apps (I disabled their permissions)

Now my hunch is the error is a conflict with AVAudioSession - no matter what audio settings are set in advance CameraKit will shut down background audio making me think it collides with audio calls.

Is it possible that CameraKit is overriding AVAudioSession settings? FYI I've now tested with FaceTime and Discord audio calling and both cause CameraKit to fail.

iPhone 12 Pro running 16.4.1

FYI this is important use case for my app as I'm making Lens games streamable

Here's a little more so you can see what's going on: Camera loads then Lens loads up (Lens has worldtracking functionality) but after ~0.1s the entire View freezes. Can still be dismissed though. Another potentially helpful detail is when the view occasionally loads without displaying the Lens (just the camera feed) it does not freeze up and the camera feed continues to stream in.

aidan

Update #2: Confirming this error does NOT occur within a facetracking lens (back or front camera doesn't matter) so it seems to be a core issue with how ARKit is handled inside CameraKit and I have suspicion the ARSessionInput(session:ARSession()) provided to CameraKit.start() is not being used as I also don't receive any events in my ARSessionDelegate so it's potentially ignoring my attempt to use providesAudioData=false which could be the reason it's failing

TL;DR: background audio call + CameraKit + Lens with worldtracking = CRASH!

aidan

@arashp @stevenxu Update #3: Confirming it does indeed suspend when receiving a call from both FaceTime and Discord during an active CameraKit session and never recovers, appearing frozen on its last rendered frame. The app remains stable, view can be dismissed, no error in console

stevenxu

@aidan Thanks for following up on that! Updated our ticket for @arashp and eng team to investigate when they get a chance.

stevenxu

@aidan We didn't forget about this! Will follow up with our eng team later today. Last I checked, they are aware of this bug and it's a matter of bandwidth to get to this when they can. Thanks for your patience!

aidan

@stevenxu woooot! thanks for the ping. If it's realistic to have it working by AWE (May 31st) would love to know as I'm going to be showing it off there and running trials with the first batch of Twitch streamers

otherwise full steam ahead on gameplay over here!!

arashp

Hi @aidan, thank you for reporting this and your patience while we looked into it. It may be that the compass, microphone, or some other sensor--used by ARKit in this case--are unavailable during a call; hence the message: "Code=102 'Required sensor failed' ". (Well, maybe "sensor is unavailable" would've been more apt.)

To handle this case, more generally, you might handle the interruption: stop your ARSessionInput and AVSessionInput when a user gets a call and start once the interruption has ended. As a rough example you might implement the handing of interruptions along these lines:

NotificationCenter.default.addObserver(self, selector: #selector(wasInterrupted), name: 
     .AVCaptureSessionWasInterrupted, object: nil)

NotificationCenter.default.addObserver(self, selector: #selector(interruptionEnded), name:
     .AVCaptureSessionInterruptionEnded, object: nil)

NotificationCenter.default.addObserver(self, selector: #selector(interruptionEnded), name:
     UIApplication.didBecomeActiveNotification, object: nil)

Or whatever cases you wish to handle, and then stop and start your inputs:

    @objc
    func wasInterrupted() {
        cameraController?.arInput.stopRunning()
        cameraController?.cameraInput?.stopRunning()
    }

    @objc
    func interruptionEnded() {
        if cameraController?.arInput.isRunning == false {
            cameraController?.arInput.startRunning()
            cameraController?.cameraInput?.startRunning()
        }
    }

Let us know whether this addresses the issue or if you have any further questions. Thanks again.

aidan

Hey @arashp, thanks for the detailed response however for my use case I need ARKit to keep alive during an active call. If I'm understanding you correctly the compass is an optional feature in ARKit so would I be able to disable the compass while using CameraKit? Then I would be able to stream the CameraKit session during screen broadcasting. Thanks so much

arashp

Appreciate the use case and feedback @aidan. Another potential cause here is that the microphone is unavailable during a call. I have asked our team to investigate. Thanks again for reporting this

aidan

@arashp @stevenxu update on this issue? this is putting me in the unfortunate position to migrate off Camera Kit

Big hunch this fix is as simple as setting ARWorldTrackingConfiguration().providesAudioData to False. This is done somewhere inside CameraKit.start which I don't have access to. If I override the delegate, I can see that the ARSession is indeed sending audio data ARSession did output audio sample buffer data

stevenxu

@aidan Thanks for holding us accountable and your patience!! I've updated the jira ticket with your hunch and eng just confirmed they are scoping it this week with your information.

This would be a huge L for our team if you were to migrate off, but completely understand why given our lack of progress and time to resolve this. For that, I apologize. No excuses on our side.

Hang tight as I'm looking to get a full update for you by the date in the calendar invite sent.