AVAudioEngine 录制麦克风输入似乎在播放音乐时停止

Question

我正在录制麦克风输入以将其与 Shazam 目录中的歌曲相匹配。这行得通，但是如果我 start() AVAudioEngine 然后会发生一些事情，比如音乐开始通过 MPMusicPlayerController.applicationMusicPlayer.play() 播放，似乎音频引擎停止或被中断。麦克风录音关闭，因此 SHSessionDelegate 永远找不到匹配项或因错误而失败，所以我的 UI 卡住了，显示它正在听，但它不再听了。发生这种情况时有没有办法通知我，以便我可以更新 UI 来处理取消？

private lazy var shazamAudioEngine = AVAudioEngine()
private lazy var shazamSession: SHSession = {
    let session = SHSession()
    session.delegate = self
    return session
}()

...

try? AVAudioSession.sharedInstance().setCategory(.record)

//Create an audio format for our buffers based on the format of the input, with a single channel (mono)
let audioFormat = AVAudioFormat(standardFormatWithSampleRate: shazamAudioEngine.inputNode.outputFormat(forBus: 0).sampleRate, channels: 1)

//Install a "tap" in the audio engine's input so that we can send buffers from the microphone to the session
shazamAudioEngine.inputNode.installTap(onBus: 0, bufferSize: 2048, format: audioFormat) { [weak self] buffer, when in
    //Whenever a new buffer comes in, we send it over to the session for recognition
    self?.shazamSession.matchStreamingBuffer(buffer, at: when)
}

do {
    try shazamAudioEngine.start()
} catch {
    ...
}

Answer 1

在我的测试中，isRunning 跟踪此状态，因此当您开始播放音乐并且麦克风停止录制时，它会从 true 变为 false。不幸的是，KVO 无法观察到属性，所以我所做的是设置一个重复的 Timer 来检测它是否更改以处理取消，确保 invalidate() 计时器在其他状态时发生变化。

audioEngineRunningTimer = Timer.scheduledTimer(withTimeInterval: 0.5, repeats: true) { [weak self] timer in    
    //the audio engine stops running when you start playing music for example, so handle cancelation here
    if self?.shazamAudioEngine.isRunning == false {
        //...
    }
}

AVAudioEngine 录制麦克风输入似乎在播放音乐时停止

AVAudioEngine recording microphone input seems to stop upon playing music

avfoundation

shazam

ios

avaudioengine