I have a Mac Catalyst video conferencing app that streams video using AVCaptureMultiCamSession. Everything has been working well for me in a variety of scenarios and hardware, but recently I got a report that virtual cameras / camera extensions do not seem to work - which I can reproduce 100% of the time by using something like OBS's virtual camera. FaceTime and Photo Booth work okay with these virtual cameras. Although my app can see and add the external AVCaptureDevice, I get an AVCaptureSessionRuntimeError posted when I start the session with a connection between the virtual camera and a AVCaptureVideoDataOutput (I don't get the error if I don't connect or add an output). The posted error is AVUnknown: AVCaptureSessionRuntimeErrorNotification with 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=0x600001dcd680 {Error Domain=NSOSStatusErrorDomain Code=-12780 "(null)"}} Which doesn't tell me too much. I do see some fig assertions just above in Console though: <<<< BWMultiStreamCameraSourceNode >>>> Fig assert: "err == 0 " at bail (BWMultiStreamCameraSourceNode.m:3964) - (err=-12780) <<<< BWMultiStreamCameraSourceNode >>>> Fig assert: "err == 0 " at bail (BWMultiStreamCameraSourceNode.m:1591) - (err=-12780) <<<< BWMultiStreamCameraSourceNode >>>> Fig assert: "err == 0 " at bail (BWMultiStreamCameraSourceNode.m:1418) - (err=-12780) <<<< FigCaptureCameraSourcePipeline >>>> Fig assert: "err == 0 " at bail (FigCaptureCameraSourcePipeline.m:3572) - (err=-12780) <<<< FigCaptureCameraSourcePipeline >>>> Fig assert: "err == 0 " at bail (FigCaptureCameraSourcePipeline.m:4518) - (err=-12780) <<<< FigCaptureCameraSourcePipeline >>>> Fig assert: "err == 0 " at bail (FigCaptureCameraSourcePipeline.m:483) - (err=-12780) I've verified formats are sane (the usual 420v 1080p 30fps I have everywhere else) and data output functions and such, but I'm a bit stuck as to where to go from here. One thing that did stand out is that in the AVCamBarcode example I can see the virtual camera in that app's preview layer, but if I create an AVCaptureVideoDataOutput and add it to the session in that example, it fails in what looks like exactly the same way that my app does, with the same assertions. Does anyone have any advice? Thanks!

Hi there, I have some existing metal rendering / shader views that I would like to use to present stereoscopic content on the Vision Pro. Is there a metal shader function / variable that lets me know which eye we're currently rendering to inside my shader? Something like Unity's unity_StereoEyeIndex? I know RealityKit has GeometrySwitchCameraIndex, so I want something similar (but outside of a RealityKit context). Many thanks, Rich

Hi there, I'm having some trouble with AVAudioMixerNode only working when there is a single input, and outputting silence or very quiet buzzing when >1 input node is connected. My setup has voice processing enabled, input going to a sink, and N source nodes going to the main mixer node, going to the output node. In all cases I am connecting nodes in the graph with the same declared format: 48kHz 1 channel Float32 PCM. This is working great for 1 source node, but as soon as I add a second it breaks. I can reproduce this behaviour in the SignalGenerator sample, when the same format is used everywhere. Again, it'll work fine with 1 source node even in this configuration, but add another and there's silence. Am I doing something wrong with formats here? Is this expected? As I understood it with voice processing on and use of a mixer node I should be able to use my own format essentially everywhere in my graph? My SignalGenerator modified repro example follows: import Foundation import AVFoundation // True replicates my real app's behaviour, which is broken. // You can remove one source node connection // to make it work even when this is true. let showBrokenState: Bool = true // SignalGenerator constants. let frequency: Float = 440 let amplitude: Float = 0.5 let duration: Float = 5.0 let twoPi = 2 * Float.pi let sine = { (phase: Float) -> Float in return sin(phase) } let whiteNoise = { (phase: Float) -> Float in return ((Float(arc4random_uniform(UINT32_MAX)) / Float(UINT32_MAX)) * 2 - 1) } // My "application" format. let format: AVAudioFormat = .init(commonFormat: .pcmFormatFloat32, sampleRate: 48000, channels: 1, interleaved: true)! // Engine setup. let engine = AVAudioEngine() let mainMixer = engine.mainMixerNode let output = engine.outputNode try! output.setVoiceProcessingEnabled(true) let outputFormat = engine.outputNode.inputFormat(forBus: 0) let sampleRate = Float(format.sampleRate) let inputFormat = format var currentPhase: Float = 0 let phaseIncrement = (twoPi / sampleRate) * frequency let srcNodeOne = AVAudioSourceNode { _, _, frameCount, audioBufferList -> OSStatus in let ablPointer = UnsafeMutableAudioBufferListPointer(audioBufferList) for frame in 0..<Int(frameCount) { let value = sine(currentPhase) * amplitude currentPhase += phaseIncrement if currentPhase >= twoPi { currentPhase -= twoPi } if currentPhase < 0.0 { currentPhase += twoPi } for buffer in ablPointer { let buf: UnsafeMutableBufferPointer<Float> = UnsafeMutableBufferPointer(buffer) buf[frame] = value } } return noErr } let srcNodeTwo = AVAudioSourceNode { _, _, frameCount, audioBufferList -> OSStatus in let ablPointer = UnsafeMutableAudioBufferListPointer(audioBufferList) for frame in 0..<Int(frameCount) { let value = whiteNoise(currentPhase) * amplitude currentPhase += phaseIncrement if currentPhase >= twoPi { currentPhase -= twoPi } if currentPhase < 0.0 { currentPhase += twoPi } for buffer in ablPointer { let buf: UnsafeMutableBufferPointer<Float> = UnsafeMutableBufferPointer(buffer) buf[frame] = value } } return noErr } engine.attach(srcNodeOne) engine.attach(srcNodeTwo) engine.connect(srcNodeOne, to: mainMixer, format: inputFormat) engine.connect(srcNodeTwo, to: mainMixer, format: inputFormat) engine.connect(mainMixer, to: output, format: showBrokenState ? inputFormat : outputFormat) // Put the input node to a sink just to match the formats and make VP happy. let sink: AVAudioSinkNode = .init { timestamp, numFrames, data in .zero } engine.attach(sink) engine.connect(engine.inputNode, to: sink, format: showBrokenState ? inputFormat : outputFormat) mainMixer.outputVolume = 0.5 try! engine.start() CFRunLoopRunInMode(.defaultMode, CFTimeInterval(duration), false) engine.stop()