ios - 在WatchOS上使用AVAudioEngine录音时禁止播放

Question

我使用AVAudioEngine从iOS的麦克风中收集PCM数据，但效果很好，但是当我尝试将项目移至WatchOS时，在录音时会得到反馈。录制时如何停止从扬声器播放？

var audioEngine = AVAudioEngine()

try AVAudioSession.sharedInstance().setCategory(.playAndRecord, mode: .default)
try AVAudioSession.sharedInstance().setActive(true)

let input = audioEngine.inputNode
let format = input.inputFormat(forBus: 0)

audioEngine.connect(input, to: audioEngine.mainMixerNode, format: format)

try! audioEngine.start()
let mixer = audioEngine.mainMixerNode

let format = mixer.outputFormat(forBus: 0)
let sampleRate = format.sampleRate
let fft_size = 2048

mixer.installTap(onBus: 0, bufferSize: UInt32(fft_size), format: format, 
            block: {(buffer: AVAudioPCMBuffer!, time: AVAudioTime!) -> Void in
    // Processing
}

Answer 1

对于遇到此问题的其他任何人，我通过删除从inputNode到mainMixerNode的连接来修复它，并将水龙头直接安装在inputNode上。在猜测之前，我的做法是创建一个反馈循环，在该循环中回放所录制的内容。不知道为什么只在WatchOS而不是在iPhone上发生这种情况……也许是从耳塞而不是麦克风旁边的扬声器回放。固定代码:

var audioEngine = AVAudioEngine()

try AVAudioSession.sharedInstance().setCategory(.playAndRecord, mode: .default)
try AVAudioSession.sharedInstance().setActive(true)

try! audioEngine.start()
let input = audioEngine.inputNode

let format = mixer.outputFormat(forBus: 0)
let sampleRate = format.sampleRate
let fft_size = 2048

input.installTap(onBus: 0, bufferSize: UInt32(fft_size), format: format, 
            block: {(buffer: AVAudioPCMBuffer!, time: AVAudioTime!) -> Void in
    // Processing
}