AVAudioSessionIOS16InpitIssue
关于这个问题:
我有一个iOS的“吉他效果”应用程序，它从输入中获取音频信号，处理它并通过输出向用户播放结果音频。该应用程序不适用于iOS设备的内置麦克风（因为会出现反馈）-用户必须通过特殊设备连接吉他：模拟设备如iRig或数字设备如iRig HD。
简而言之：从iOS 16开始，我遇到了AVAudioSession的奇怪行为，导致我的应用程序崩溃。在iOS 16中，AVAudioSession路由的输入始终是MicrophoneBuiltIn-无论我是否连接任何外部麦克风，如iRig设备或带麦克风的耳机。即使我尝试通过为AVAudioSession分配preferredInput来手动切换到外部麦克风，它也不会改变路线-输入始终是MicrophoneBuiltIn。在iOS 15和更早版本的iOS中，iOS会自动将路由的输入更改为您连接到iOS设备的任何外部麦克风。您可以通过为AVAudioSession分配preferredInput属性来控制输入。
项目结构:
这是一个非常小的项目，用于重现此问题。所有代码都在ViewController类中。
- 我创建了一个playAndRecord AVAudioSession，并订阅routeChangeNotification通知：
NotificationCenter.default.addObserver(self, selector: #selector(handleRouteChange), name: AVAudioSession.routeChangeNotification, object: nil)
let audioSession = AVAudioSession.sharedInstance()
do {
try audioSession.setCategory(AVAudioSession.Category.playAndRecord, options: .mixWithOthers)
try audioSession.setActive(true, options: [])
} catch {
print("AVAudioSession init error: \(error)")
}
当我收到通知时，我会打印可用音频输入列表、首选输入和当前的音频路由：
@objc func handleRouteChange(notification: Notification) {
print("\nHANDLE ROUTE CHANGE")
print("AVAILABLE INPUTS: \(AVAudioSession.sharedInstance().availableInputs ?? [])")
print("PREFERRED INPUT: \(String(describing: AVAudioSession.sharedInstance().preferredInput))")
print("CURRENT ROUTE: \(AVAudioSession.sharedInstance().currentRoute)\n")
}
我有一个按钮，点击后会显示所有可用音频输入的列表，并提供将每个输入设置为首选项的方法。
@IBAction func selectPreferredInputClick(_ sender: UIButton) {
let inputs = AVAudioSession.sharedInstance().availableInputs ?? []
let title = "Select Preferred Input"
let message = "Current Preferred Input: \(String(describing: AVAudioSession.sharedInstance().preferredInput?.portName))\nCurrent Route Input \(String(describing: AVAudioSession.sharedInstance().currentRoute.inputs.first?.portName))"
let alert = UIAlertController(title: title, message: message, preferredStyle: .alert)
for input in inputs {
alert.addAction(UIAlertAction(title: input.portName, style: .default) {_ in
print("\n\(title)")
print("\(message) New Preferred Input: \(input.portName)\n")
do {
try AVAudioSession.sharedInstance().setPreferredInput(input)
} catch {
print("Set Preferred Input Error: \(error)")
}
})
}
alert.addAction(UIAlertAction(title: "Cancel", style: .cancel))
present(alert, animated: true)
}
iOS 16行为:
当我启动应用程序而没有连接任何外部麦克风并初始化AVAudioSession时，我会得到以下日志:
HANDLE ROUTE CHANGE
AVAILABLE INPUTS: [<AVAudioSessionPortDescription: 0x2837101e0, type = MicrophoneBuiltIn; name = iPhone Microphone; UID = Built-In Microphone; selectedDataSource = Bottom>]
PREFERRED INPUT: nil
CURRENT ROUTE: <AVAudioSessionRouteDescription: 0x283710a80,
inputs = (
"<AVAudioSessionPortDescription: 0x283710a50, type = MicrophoneBuiltIn; name = iPhone Microphone; UID = Built-In Microphone; selectedDataSource = Bottom>"
);
outputs = (
"<AVAudioSessionPortDescription: 0x283710600, type = Receiver; name = Receiver; UID = Built-In Receiver; selectedDataSource = (null)>"
)>
这很好。然后我连接了iRig设备（基本上是外部麦克风），我看到了以下日志：
HANDLE ROUTE CHANGE
AVAILABLE INPUTS: [<AVAudioSessionPortDescription: 0x283718630, type = MicrophoneBuiltIn; name = iPhone Microphone; UID = Built-In Microphone; selectedDataSource = Bottom>, <AVAudioSessionPortDescription: 0x283718500, type = MicrophoneWired; name = Headset Microphone; UID = Wired Microphone; selectedDataSource = (null)>]
PREFERRED INPUT: nil
CURRENT ROUTE: <AVAudioSessionRouteDescription: 0x283700140,
inputs = (
"<AVAudioSessionPortDescription: 0x283700160, type = MicrophoneBuiltIn; name = iPhone Microphone; UID = Built-In Microphone; selectedDataSource = Bottom>"
);
outputs = (
"<AVAudioSessionPortDescription: 0x2837001f0, type = Headphones; name = Headphones; UID = Wired Headphones; selectedDataSource = (null)>"
)>
你会发现- 有线麦克风出现在可用输入列表中，但路由的输入仍然是内置麦克风。 然后我尝试先将AVAudioSession的preferredInput更改为有线麦克风，然后改为内置麦克风，再改回有线麦克风：
Select Preferred Input
Current Preferred Input: nil
Current Route Input Optional("iPhone Microphone") New Preferred Input: Headset Microphone
Select Preferred Input
Current Preferred Input: Optional("Headset Microphone")
Current Route Input Optional("iPhone Microphone") New Preferred Input: iPhone Microphone
HANDLE ROUTE CHANGE
AVAILABLE INPUTS: [<AVAudioSessionPortDescription: 0x28299da70, type = MicrophoneBuiltIn; name = iPhone Microphone; UID = Built-In Microphone; selectedDataSource = Bottom>, <AVAudioSessionPortDescription: 0x28299d930, type = MicrophoneWired; name = Headset Microphone; UID = Wired Microphone; selectedDataSource = (null)>]
PREFERRED INPUT: Optional(<AVAudioSessionPortDescription: 0x282994330, type = MicrophoneBuiltIn; name = iPhone Microphone; UID = Built-In Microphone; selectedDataSource = Bottom>)
CURRENT ROUTE: <AVAudioSessionRouteDescription: 0x2829912d0,
inputs = (
"<AVAudioSessionPortDescription: 0x282991820, type = MicrophoneBuiltIn; name = iPhone Microphone; UID = Built-In Microphone; selectedDataSource = Bottom>"
);
outputs = (
"<AVAudioSessionPortDescription: 0x282991740, type = Headphones; name = Headphones; UID = Wired Headphones; selectedDataSource = (null)>"
)>
Select Preferred Input
Current Preferred Input: Optional("iPhone Microphone")
Current Route Input Optional("iPhone Microphone") New Preferred Input: Headset Microphone
HANDLE ROUTE CHANGE
AVAILABLE INPUTS: [<AVAudioSessionPortDescription: 0x28299d7c0, type = MicrophoneBuiltIn; name = iPhone Microphone; UID = Built-In Microphone; selectedDataSource = Bottom>, <AVAudioSessionPortDescription: 0x28299d8c0, type = MicrophoneWired; name = Headset Microphone; UID = Wired Microphone; selectedDataSource = (null)>]
PREFERRED INPUT: Optional(<AVAudioSessionPortDescription: 0x2829918e0, type = MicrophoneWired; name = Headset Microphone; UID = Wired Microphone; selectedDataSource = (null)>)
CURRENT ROUTE: <AVAudioSessionRouteDescription: 0x28299d530,
inputs = (
"<AVAudioSessionPortDescription: 0x28299d510, type = MicrophoneBuiltIn; name = iPhone Microphone; UID = Built-In Microphone; selectedDataSource = Bottom>"
);
outputs = (
"<AVAudioSessionPortDescription: 0x28299d6d0, type = Headphones; name = Headphones; UID = Wired Headphones; selectedDataSource = (null)>"
)>
无论选择什么输入设备，AudioSession路由的输入设备都是MicrophoneBuiltIn。
iOS 15行为：
在iOS 15中，一切都不同（而且更好）。当我启动应用程序并初始化AVAudioSession时，如果没有连接外部麦克风，我会得到与iOS 16相同的日志记录。
HANDLE ROUTE CHANGE
AVAILABLE INPUTS: [<AVAudioSessionPortDescription: 0x2813cc930, type = MicrophoneBuiltIn; name = iPad Microphone; UID = Built-In Microphone; selectedDataSource = Top>]
PREFERRED INPUT: nil
CURRENT ROUTE: <AVAudioSessionRouteDescription: 0x2813cc9c0,
inputs = (
"<AVAudioSessionPortDescription: 0x2813cc9b0, type = MicrophoneBuiltIn; name = iPad Microphone; UID = Built-In Microphone; selectedDataSource = Top>"
);
outputs = (
"<AVAudioSessionPortDescription: 0x2813cc6b0, type = Speaker; name = Speaker; UID = Speaker; selectedDataSource = (null)>"
)>
然后我连接iRig设备（基本上是外部麦克风），我看到以下日志：
HANDLE ROUTE CHANGE
AVAILABLE INPUTS: [<AVAudioSessionPortDescription: 0x2813d0450, type = MicrophoneBuiltIn; name = iPad Microphone; UID = Built-In Microphone; selectedDataSource = Top>, <AVAudioSessionPortDescription: 0x2813d04a0, type = MicrophoneWired; name = YC136 USB AUDIO; UID = AppleUSBAudioEngine:Generic:YC136 USB AUDIO:20170726905926:2; selectedDataSource = (null)>]
PREFERRED INPUT: nil
CURRENT ROUTE: <AVAudioSessionRouteDescription: 0x2813e40f0,
inputs = (
"<AVAudioSessionPortDescription: 0x2813e4110, type = MicrophoneWired; name = YC136 USB AUDIO; UID = AppleUSBAudioEngine:Generic:YC136 USB AUDIO:20170726905926:2; selectedDataSource = (null)>"
);
outputs = (
"<AVAudioSessionPortDescription: 0x2813e4150, type = Headphones; name = YC136 USB AUDIO; UID = AppleUSBAudioEngine:Generic:YC136 USB AUDIO:20170726905926:1; selectedDataSource = (null)>"
)>
HANDLE ROUTE CHANGE
AVAILABLE INPUTS: [<AVAudioSessionPortDescription: 0x2813e40e0, type = MicrophoneBuiltIn; name = iPad Microphone; UID = Built-In Microphone; selectedDataSource = Top>, <AVAudioSessionPortDescription: 0x2813e4160, type = MicrophoneWired; name = YC136 USB AUDIO; UID = AppleUSBAudioEngine:Generic:YC136 USB AUDIO:20170726905926:2; selectedDataSource = (null)>]
PREFERRED INPUT: nil
CURRENT ROUTE: <AVAudioSessionRouteDescription: 0x2813dc1c0,
inputs = (
"<AVAudioSessionPortDescription: 0x2813dc1e0, type = MicrophoneWired; name = YC136 USB AUDIO; UID = AppleUSBAudioEngine:Generic:YC136 USB AUDIO:20170726905926:2; selectedDataSource = (null)>"
);
outputs = (
"<AVAudioSessionPortDescription: 0x2813dc220, type = Headphones; name = YC136 USB AUDIO; UID = AppleUSBAudioEngine:Generic:YC136 USB AUDIO:20170726905926:1; selectedDataSource = (null)>"
)>
这里有两个主要的区别：
- routeChangeNotification被调用了两次
- AVAudioSession路由的输入是MicrophoneWired 然后我尝试改变AVAudioSession的首选输入，并得到以下日志:
Select Preferred Input
Current Preferred Input: nil
Current Route Input Optional("YC136 USB AUDIO") New Preferred Input: iPad Microphone
HANDLE ROUTE CHANGE
AVAILABLE INPUTS: [<AVAudioSessionPortDescription: 0x2813c8db0, type = MicrophoneBuiltIn; name = iPad Microphone; UID = Built-In Microphone; selectedDataSource = Top>, <AVAudioSessionPortDescription: 0x2813c8e00, type = MicrophoneWired; name = YC136 USB AUDIO; UID = AppleUSBAudioEngine:Generic:YC136 USB AUDIO:20170726905926:2; selectedDataSource = (null)>]
PREFERRED INPUT: Optional(<AVAudioSessionPortDescription: 0x2813d8ad0, type = MicrophoneBuiltIn; name = iPad Microphone; UID = Built-In Microphone; selectedDataSource = Top>)
CURRENT ROUTE: <AVAudioSessionRouteDescription: 0x2813c0c40,
inputs = (
"<AVAudioSessionPortDescription: 0x2813c1300, type = MicrophoneBuiltIn; name = iPad Microphone; UID = Built-In Microphone; selectedDataSource = Top>"
);
outputs = (
"<AVAudioSessionPortDescription: 0x2813c10b0, type = Headphones; name = YC136 USB AUDIO; UID = AppleUSBAudioEngine:Generic:YC136 USB AUDIO:20170726905926:1; selectedDataSource = (null)>"
)>
Select Preferred Input
Current Preferred Input: Optional("iPad Microphone")
Current Route Input Optional("iPad Microphone") New Preferred Input: YC136 USB AUDIO
HANDLE ROUTE CHANGE
AVAILABLE INPUTS: [<AVAudioSessionPortDescription: 0x2813c0d50, type = MicrophoneBuiltIn; name = iPad Microphone; UID = Built-In Microphone; selectedDataSource = Top>, <AVAudioSessionPortDescription: 0x2813c0a20, type = MicrophoneWired; name = YC136 USB AUDIO; UID = AppleUSBAudioEngine:Generic:YC136 USB AUDIO:20170726905926:2; selectedDataSource = (null)>]
PREFERRED INPUT: Optional(<AVAudioSessionPortDescription: 0x2813e4140, type = MicrophoneWired; name = YC136 USB AUDIO; UID = AppleUSBAudioEngine:Generic:YC136 USB AUDIO:20170726905926:2; selectedDataSource = (null)>)
CURRENT ROUTE: <AVAudioSessionRouteDescription: 0x2813cdaa0,
inputs = (
"<AVAudioSessionPortDescription: 0x2813cdad0, type = MicrophoneWired; name = YC136 USB AUDIO; UID = AppleUSBAudioEngine:Generic:YC136 USB AUDIO:20170726905926:2; selectedDataSource = (null)>"
);
outputs = (
"<AVAudioSessionPortDescription: 0x2813cdeb0, type = Headphones; name = YC136 USB AUDIO; UID = AppleUSBAudioEngine:Generic:YC136 USB AUDIO:20170726905926:1; selectedDataSource = (null)>"
)>
如您所见，路由的输入与AVAudioSession的首选输入匹配。
结论：
请告知是否有任何方法使iOS 16的行为与iOS 15及以下版本相同。我搜索了iOS 16的发布说明，没有找到提到AVAudioSession的任何信息。如果没有办法，请告知管理AVAudioSession路由输入源的正确方法。非常感谢任何建议。