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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，但如果我发生start()了AVAudioEngine一些事情，比如音乐开始通过 播放MPMusicPlayerController.applicationMusicPlayer.play()，音频引擎似乎停止或被中断。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，显示它不再在听了。有没有办法在发生这种情况时得到通知，以便我可以更新 UI 以处理取消？

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 {
    ...
}
4

1 回答 1

1

在我的测试isRunning中跟踪此状态，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 无法观察到该属性，因此我所做的是设置重复Timer以检测它是否更改以处理取消，并确保invalidate()在发生其他状态更改时使用计时器。

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 {
        //...
    }
}
于 2021-07-11T16:14:50.463 回答