同时使用 SFSpeechRecognizer 和 AVSpeechSythesizer 时如何正确设置 AVAudioSession 和 AVAudioEngine

Question

我正在尝试创建一个同时利用 STT（语音到文本）和 TTS（文本到语音）的应用程序。但是，我运行遇到了一些模糊的问题，非常感谢您的专业知识。

该应用程序包含一个位于屏幕中央的按钮，单击该按钮可使用以下代码启动所需的语音识别功能。

// MARK: - Constant Properties

let audioEngine = AVAudioEngine()



// MARK: - Optional Properties

var recognitionRequest: SFSpeechAudioBufferRecognitionRequest?
var recognitionTask: SFSpeechRecognitionTask?
var speechRecognizer: SFSpeechRecognizer?



// MARK: - Functions

internal func startSpeechRecognition() {

    // Instantiate the recognitionRequest property.
    self.recognitionRequest = SFSpeechAudioBufferRecognitionRequest()

    // Set up the audio session.
    let audioSession = AVAudioSession.sharedInstance()
    do {
        try audioSession.setCategory(.record, mode: .measurement, options: [.defaultToSpeaker, .duckOthers])
        try audioSession.setActive(true, options: .notifyOthersOnDeactivation)
    } catch {
        print("An error has occurred while setting the AVAudioSession.")
    }

    // Set up the audio input tap.
    let inputNode = self.audioEngine.inputNode
    let inputNodeFormat = inputNode.outputFormat(forBus: 0)

    self.audioEngine.inputNode.installTap(onBus: 0, bufferSize: 512, format: inputNodeFormat, block: { [unowned self] buffer, time in
        self.recognitionRequest?.append(buffer)
    })

    // Start the recognition task.
    guard
        let speechRecognizer = self.speechRecognizer,
        let recognitionRequest = self.recognitionRequest else {
            fatalError("One or more properties could not be instantiated.")
    }

    self.recognitionTask = speechRecognizer.recognitionTask(with: recognitionRequest, resultHandler: { [unowned self] result, error in

        if error != nil {

            // Stop the audio engine and recognition task.
            self.stopSpeechRecognition()

        } else if let result = result {

            let bestTranscriptionString = result.bestTranscription.formattedString

            self.command = bestTranscriptionString
            print(bestTranscriptionString)

        }

    })

    // Start the audioEngine.
    do {
        try self.audioEngine.start()
    } catch {
        print("Could not start the audioEngine property.")
    }

}



internal func stopSpeechRecognition() {

    // Stop the audio engine.
    self.audioEngine.stop()
    self.audioEngine.inputNode.removeTap(onBus: 0)

    // End and deallocate the recognition request.
    self.recognitionRequest?.endAudio()
    self.recognitionRequest = nil

    // Cancel and deallocate the recognition task.
    self.recognitionTask?.cancel()
    self.recognitionTask = nil

}

当单独使用时，这段代码就像一个魅力。但是，当我想使用 AVSpeechSynthesizer 对象阅读转录的文本时，似乎没有什么是清楚的。

我查看了多个 Stack Overflow 帖子的建议，建议修改

audioSession.setCategory(.record, mode: .measurement, options: [.defaultToSpeaker, .duckOthers])

给以下

audioSession.setCategory(.playAndRecord, mode: .default, options: [.defaultToSpeaker, .duckOthers])

还是徒劳。在分别运行 STT 和 TTS 之后，应用程序仍然崩溃。

解决方案是让我使用这个而不是前面提到的

audioSession.setCategory(.multiRoute, mode: .default, options: [.defaultToSpeaker, .duckOthers])

这让我完全不知所措，因为我真的不知道发生了什么错综复杂的事情。如果有任何相关解释，我将不胜感激！

Answer 1

我也在开发一个同时包含 SFSpeechRecognizer 和 AVSpeechSythesizer 的应用程序，对我来说 .setCategory(.playAndRecord, mode: .default) 工作正常，它是满足我们需求的最佳类别，according to Apple。甚至，我能够 .speak() SFSpeechRecognitionTask 的每个转录，而音频引擎是运行没有任何问题。我的意见是你的程序逻辑中的某个地方导致了崩溃。如果您可以用相应的错误更新您的问题，那就太好了。

关于 .multiRoute 类别为何有效：我猜 AVAudioInputNode 有问题。如果您在控制台中看到这样的错误

Terminating app due to uncaught exception 'com.apple.coreaudio.avfaudio', reason: 'required condition is false: IsFormatSampleRateAndChannelCountValid(hwFormat)

或者像这样

Terminating app due to uncaught exception 'com.apple.coreaudio.avfaudio', reason: 'required condition is false: nullptr == Tap()

您只需要对代码的某些部分重新排序，例如将音频会话的设置移动到只被调用一次的地方，或者确保输入节点的抽头总是在安装 新的之前删除，即使识别任务是否成功完成也是如此。也许（我从未使用过它）.multiRoute 能够通过 its nature 使用不同的音频流和路由来重用相同的输入节点。

我按照 Apple 的 WWDC session:

在我的程序中使用的逻辑保留在下面

设置类别

override func viewDidLoad() { //or init() or when necessarily
    super.viewDidLoad()
    try? AVAudioSession.sharedInstance().setCategory(.playAndRecord, mode: .default)
}

Validations/permissions

func shouldProcessSpeechRecognition() {
    guard AVAudioSession.sharedInstance().recordPermission == .granted,
        speechRecognizerAuthorizationStatus == .authorized,
        let speechRecognizer = speechRecognizer, speechRecognizer.isAvailable else { return }
        //Continue only if we have authorization and recognizer is available

        startSpeechRecognition()
}

正在启动 STT

func startSpeechRecognition() {
    let format = audioEngine.inputNode.outputFormat(forBus: 0)
    audioEngine.inputNode.installTap(onBus: 0, bufferSize: 1024, format: format) { [unowned self] (buffer, _) in
        self.recognitionRequest.append(buffer)
    }
    audioEngine.prepare()
    do {
        try audioEngine.start()
        recognitionTask = speechRecognizer!.recognitionTask(with: recognitionRequest, resultHandler: {...}
    } catch {...}
}

结束 STT

func endSpeechRecognition() {
    recognitionTask?.finish()
    stopAudioEngine()
}

正在取消 STT

func cancelSpeechRecognition() {
    recognitionTask?.cancel()
    stopAudioEngine()
}

正在停止音频引擎

func stopAudioEngine() {
    audioEngine.stop()
    audioEngine.inputNode.removeTap(onBus: 0)
    recognitionRequest.endAudio()        
}

这样，我可以在我的代码中的任何地方调用一个 AVSpeechSynthesizer 实例并说出一句话。

同时使用 SFSpeechRecognizer 和 AVSpeechSythesizer 时如何正确设置 AVAudioSession 和 AVAudioEngine

How to correctly set up AVAudioSession and AVAudioEngine when using both SFSpeechRecognizer and AVSpeechSythesizer

avfoundation

ios

avaudiosession

swift

avaudioengine