音频套件输出更改为入耳式扬声器

Question

我在我的应用程序中实现了AudioKit"麦克风分析"示例 https://audiokit.io/examples/MicrophoneAnalysis/。

我想分析麦克风输入频率，然后播放接近确定频率的正确音符。

通常，声音输出是连接到我的iPhone的扬声器或蓝牙设备，但是在实施"麦克风分析"示例后，声音输出更改为iPhone顶部的小型扬声器，通常在您接到电话时使用。 如何像以前一样切换到"普通"扬声器或连接的蓝牙设备？

var mic: AKMicrophone!
var tracker: AKFrequencyTracker!
var silence: AKBooster!

func initFrequencyTracker() {
AKSettings.audioInputEnabled = true
mic = AKMicrophone()
tracker = AKFrequencyTracker(mic)
silence = AKBooster(tracker, gain: 0)
}
func deinitFrequencyTracker() {
plotTimer.invalidate()
do {
try AudioKit.stop()
AudioKit.output = nil
} catch {
print(error)
}
}
func initPlotTimer() {
AudioKit.output = silence
do {
try AudioKit.start()
} catch {
AKLog("AudioKit did not start!")
}
setupPlot()
plotTimer = Timer.scheduledTimer(timeInterval: 0.1, target: self, selector: #selector(updatePlotUI), userInfo: nil, repeats: true)
}
func setupPlot() {
let plot = AKNodeOutputPlot(mic, frame: audioInputPlot.bounds)
plot.translatesAutoresizingMaskIntoConstraints = false
plot.alpha = 0.3
plot.plotType = .rolling
plot.shouldFill = true
plot.shouldCenterYAxis = false
plot.shouldMirror = true
plot.color = UIColor(named: uiFarbe)
audioInputPlot.addSubview(plot)
// Pin the AKNodeOutputPlot to the audioInputPlot
var constraints = [plot.leadingAnchor.constraint(equalTo: audioInputPlot.leadingAnchor)]
constraints.append(plot.trailingAnchor.constraint(equalTo: audioInputPlot.trailingAnchor))
constraints.append(plot.topAnchor.constraint(equalTo: audioInputPlot.topAnchor))
constraints.append(plot.bottomAnchor.constraint(equalTo: audioInputPlot.bottomAnchor))
constraints.forEach { $0.isActive = true }
}
@objc func updatePlotUI() {
if tracker.amplitude > 0.1 {
let trackerFrequency = Float(tracker.frequency)
guard trackerFrequency < 7_000 else {
// This is a bit of hack because of modern Macbooks giving super high frequencies
return
}
var frequency = trackerFrequency
while frequency > Float(noteFrequencies[noteFrequencies.count - 1]) {
frequency /= 2.0
}
while frequency < Float(noteFrequencies[0]) {
frequency *= 2.0
}
var minDistance: Float = 10_000.0
var index = 0
for i in 0..<noteFrequencies.count {
let distance = fabsf(Float(noteFrequencies[i]) - frequency)
if distance < minDistance {
index = i
minDistance = distance
}
}
//                let octave = Int(log2f(trackerFrequency / frequency))
frequencyLabel.text = String(format: "%0.1f", tracker.frequency)
if frequencyTranspose(note: notesToTanspose[index]) != droneLabel.text {
note = frequencyTranspose(note: notesToTanspose[index])
droneLabel.text = note
DispatchQueue.main.asyncAfter(deadline: .now() + 0.03, execute: {
self.prepareSinglePlayerFirstForStart(note: self.note)
self.startSinglePlayer()
})
}
}
}
func frequencyTranspose(note: String) -> String {
var indexNote = notesToTanspose.firstIndex(of: note)!
let chosenInstrument = UserDefaults.standard.object(forKey: "whichInstrument") as! String
if chosenInstrument == "Bb" {
if indexNote + 2 >= notesToTanspose.count {
indexNote -= 12
}
return notesToTanspose[indexNote + 2]
} else if chosenInstrument == "Eb" {
if indexNote - 3 < 0 {
indexNote += 12
}
return notesToTanspose[indexNote - 3]
} else {
return note
}
}

Answer 1

最好控制会话设置，因此首先在应用程序中创建一个方法，以便在初始化期间处理该问题。

接下来，有一个示例，我设置了一个类别和所需的选项：

func start() {
do {
let session = AVAudioSession.sharedInstance()
try session.setCategory(.playAndRecord, options: .defaultToSpeaker)
try session.setActive(true, options: .notifyOthersOnDeactivation)
try session.overrideOutputAudioPort(AVAudioSession.PortOverride.speaker)
try AudioKit.start()
} catch {
// your error handler
}
}

您可以在initPlotTimer中调用 AudioKit.Start((start调用该方法。

上面的例子是使用AVAudioSession，我相信这就是AKSettings包装的内容(请随意编辑我的答案以免误导未来的读者，因为我目前没有查看 AudioKit 源代码(。

现在AVAudioSession已经公开，让我们坚持使用AudioKit提供的方法，因为这就是您正在处理的问题。

这是另一个使用AKSettings的示例：

func start() {
do {
AKSettings.channelCount = 2
AKSettings.ioBufferDuration = 0.002
AKSettings.audioInputEnabled = true
AKSettings.bufferLength = .medium
AKSettings.defaultToSpeaker = true
// check docs for other options and settings
try AKSettings.setSession(category: .playAndRecord, with: [.defaultToSpeaker, .allowBluetooth])
try AudioKit.start()
} catch {
// your handler
}
}

请记住，您不必将其称为start或运行 AudioKit 的start方法，我只是公开初始化阶段，以使其对您和其他用例具有可读性。

参考：

https://developer.apple.com/documentation/avfoundation/avaudiosession/categoryoptions

https://audiokit.io/docs/Classes/AKSettings.html