AVAudioSession: Mac Catalyst speaker reports input latency as 0
Originator: | jscalo | ||
Number: | rdar://FB8983951 | Date Originated: | 1/28/2021 |
Status: | Open | Resolved: | |
Product: | AVFoundation | Product Version: | iOS 14 |
Classification: | Unexpected behavior | Reproducible: | Always |
Running an iOS via Catalyst on a Mac using built-in mic & speaker, AVAudioSession always reports the inputLatency as 0. private func initAudioSession() { do { audioSession = AVAudioSession() try audioSession.setCategory(.playAndRecord, options: [.allowBluetooth, .allowBluetoothA2DP, .defaultToSpeaker]) let builtInTypes: [AVAudioSession.Port] = [.lineIn, .builtInMic] let connectedTypes: [AVAudioSession.Port] = [.headsetMic, .usbAudio, .bluetoothHFP] guard let inputs = audioSession.availableInputs else { preconditionFailure() } var input: AVAudioSessionPortDescription! // Prefer airpods/headphones if connected if let connectedInput = (inputs.first { connectedTypes.contains($0.portType) }) { input = connectedInput } if input == nil { if let builtInInput = (inputs.first { builtInTypes.contains($0.portType) }) { input = builtInInput } } precondition(input != nil) try audioSession.setPreferredInput(input) try audioSession.setActive(true) } catch { assertionFailure("*** Caught: \(error)") } } At some point during the capture session: func printLatencyInfo() { print("audioSession.inputLatency: \(audioSession.inputLatency)") print("audioSession.outputLatency: \(audioSession.outputLatency)") print("audioSession.ioBufferDuration: \(audioSession.ioBufferDuration)") print("engine.mainMixerNode.auAudioUnit.latency: \(engine.mainMixerNode.auAudioUnit.latency)") print("engine.inputNode.auAudioUnit.latency: \(engine.inputNode.auAudioUnit.latency)") print("engine.outputNode.auAudioUnit.latency: \(engine.outputNode.auAudioUnit.latency)") print("engine.mainMixerNode.outputPresentationLatency: \(engine.mainMixerNode.outputPresentationLatency)") print("engine.inputNode.outputPresentationLatency: \(engine.inputNode.outputPresentationLatency)") print("engine.outputNode.outputPresentationLatency: \(engine.outputNode.outputPresentationLatency)") print("engine.inputNode.auAudioUnit.latency: \(engine.inputNode.auAudioUnit.latency)") print("engine.outputNode.auAudioUnit.latency: \(engine.outputNode.auAudioUnit.latency)") print("metronomePlayerNode.auAudioUnit.latency: \(metronomePlayerNode.auAudioUnit.latency)") } And here audioSession.inputLatency is always 0 on Mac Catalyst with built-in mic & speaker.
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