ios - Swift:声音输出和麦克风输入 |使用 AudioKit |

Question

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我正在使用 >Xcode 9.2 版<
我正在使用 >AudioKit 版本 4.0.4<

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我已经写了一些代码，你可以在下面找到它们应该能够

• 播放特定的声音(频率:500.0HZ)
• “收听”麦克风输入并实时计算频率

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如果我调用 playSound() 或 receiveSound() separated 一切看起来都很好，并且确实如我预期的那样工作。但是之后调用 playSound() 和 receiveSound() 呢？正是在那里，我遇到了大问题。

这就是我想让代码工作的方式:

SystemClass.playSound() //play sound
DispatchQueue.main.asyncAfter(deadline: (DispatchTime.now() + 3.0)) {
   SystemClass.receiveSound() //get microphone input 3 seconds later
}

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let SystemClass: System = System()
class System {
    public init() { }

    func playSound() {
        let sound = AKOscillator()
        AudioKit.output = sound
        AudioKit.start()
        sound.frequency = 500.0
        sound.amplitude = 0.5
        sound.start()
        DispatchQueue.main.asyncAfter(deadline: (DispatchTime.now() + 2.0)) {
            sound.stop()
        }
    }


    var tracker: AKFrequencyTracker!
    func receiveSound() {
        AudioKit.stop()
        AKSettings.audioInputEnabled = true
        let mic = AKMicrophone()
        tracker = AKFrequencyTracker(mic)
        let silence = AKBooster(tracker, gain: 0)
        AudioKit.output = silence
        AudioKit.start()
        Timer.scheduledTimer( timeInterval: 0.1, target: self, selector: #selector(SystemClass.outputFrequency), userInfo: nil, repeats: true)
    }

    @objc func outputFrequency() {
        print("Frequency: \(tracker.frequency)")
    }
}

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这些消息是我每次运行代码时收到的一些编译器错误消息(调用 playSound() 和调用 receiveSound () 3秒后):

AVAEInternal.h:103:_AVAE_CheckNoErr: [AVAudioEngineGraph.mm:1266:Initialize: (err = AUGraphParser::InitializeActiveNodesInOutputChain(ThisGraph, kOutputChainOptimizedTraversal, *GetOutputNode(), isOutputChainActive)): error -10875

AVAudioEngine.mm:149:-[AVAudioEngine prepare]: Engine@0x1c401bff0: could not initialize, error = -10875

[MediaRemote] [AVOutputContext] WARNING: AVF context unavailable for sharedSystemAudioContext

[AVAudioEngineGraph.mm:1266:Initialize: (err = AUGraphParser::InitializeActiveNodesInOutputChain(ThisGraph, kOutputChainOptimizedTraversal, *GetOutputNode(), isOutputChainActive)): error -10875

Fatal error: AudioKit: Could not start engine. error: Error 

Domain=com.apple.coreaudio.avfaudio Code=-10875 "(null)" UserInfo={failed call=err = AUGraphParser::InitializeActiveNodesInOutputChain(ThisGraph, kOutputChainOptimizedTraversal, *GetOutputNode(), isOutputChainActive)}.: file /Users/megastep/src/ak/AudioKit/AudioKit/Common/Internals/AudioKit.swift, line 243

Answer 1

我相信您的大部分问题是由于在使用它们的函数中本地声明 AKNodes 造成的:

   let sound = AKOscillator()
   let mic = AKMicrophone()        
   let silence = AKBooster(tracker, gain: 0)

将它们声明为实例变量，如所述here .