swift AVAudioEngine故障

Question

我正在使用AVAudioCV录制声音，并使用苹果内置的口述进行分析。但是，当我尝试用按钮打开音频引擎时，音频缓冲区立即完成，并且没有拾取任何声音。然而，只有当我第二次打开按钮时，缓冲区才开始出现故障，这让我相信，当我停止录制时，一些点击没有从音频引擎中删除，并且这些点击相互碰撞，立即结束了缓冲区。

我已经搜索了许多关于AVAudioCV中由于未删除的水龙头而导致的小故障的帖子，但到目前为止我还没有看到任何有用的帖子。这就是我所拥有的：

 func recognizeAudioStream() {
         let speechRecognizer = SFSpeechRecognizer()
         
         //performs speech recognition on live audio; as audio is captured, call append
         //to request object, call endAudio() to end speech recognition
         var recognitionRequest: SFSpeechAudioBufferRecognitionRequest?
         
         //determines & edits state of speech recognition task (end, start, cancel, etc)
         var recognitionTask: SFSpeechRecognitionTask?
         
         let audioEngine = AVAudioEngine()
         
         
         func startRecording() throws{
             
             //cancel previous audio task
             recognitionTask?.cancel()
             recognitionTask = nil
             
             //get info from microphone
             let audioSession = AVAudioSession.sharedInstance()
             try audioSession.setCategory(.record, mode: .measurement, options: .duckOthers)
             try audioSession.setActive(true, options: .notifyOthersOnDeactivation)
             
             let inputNode = audioEngine.inputNode
             
             //audio buffer; takes a continuous input of audio and recognizes speech
             recognitionRequest = SFSpeechAudioBufferRecognitionRequest()
             //allows device to print results of your speech before you're done talking
             recognitionRequest?.shouldReportPartialResults = true
             
             
             recognitionTask = speechRecognizer!.recognitionTask(with: recognitionRequest!) {result, error in
                 
                 var isFinal = false
                 
                 if let result = result{ //if we can let result be the nonoptional version of result, then
                     isFinal = result.isFinal
                     print("Text: \(result.bestTranscription.formattedString)")
                     
                 }
                 
                 if error != nil || result!.isFinal{ //if an error occurs or we're done speaking
                     
                     audioEngine.stop()
                     inputNode.removeTap(onBus: 0)
                     
                     recognitionTask = nil
                     recognitionRequest = nil

                     let bufferText = result?.bestTranscription.formattedString.components(separatedBy: (" "))
                     print("completed buffer")
                     
                     self.addToDictionary(wordNames: bufferText)
                     self.populateTempWords()
                     
                     wordsColl.reloadData()
 
                     do{
                         try startRecording()
                     }
                     catch{
                         print(error)
                     }
                     
                 }
             
             }
             
             //configure microphone; let the recording format match with that of the bus we are using
             let recordingFormat = inputNode.outputFormat(forBus: 0)
             
             //contents of buffer will be dumped into recognitionRequest and into result, where
             //it will then be transcribed and printed out
             //1024 bytes = dumping "limit": once buffer fills to 1024 bytes, it is appended to recognitionRequest
             inputNode.installTap(onBus: 0, bufferSize: 1024, format: recordingFormat) { (buffer: AVAudioPCMBuffer, when: AVAudioTime) in
                 recognitionRequest?.append(buffer)
             }
             
             audioEngine.prepare()
             try audioEngine.start()
         }
         
         do{
             if(!isRecording){
                audioEngine.mainMixerNode.removeTap(onBus: 0)
                audioEngine.stop()
                 return
             }
             try startRecording()
         }
         catch{
             print(error)
         }
         
         
     }

上面是我的recognizeAudioStream()函数。它首先初始化SFSpeechRecognizer()和AVAudioEngine()，然后调用startRecording()。取消之前的音频任务，并将AVAudioEngine()类型的audioEngine设置为安装tap的inputNode。变量isFinal存储变量isFinal的数据成员result，该成员在其上方的recognitionTask()闭包中设置。当1024字节过滤器填满并且inputNode上的抽头被移除时，isFinal设置为真。recognitionTask被重置，缓冲区中的文本被分析并加载到我的单词字典中。在这个块的下面是buffer和audioEngine的设置。

最后，do/catch块检查audioEngine是否应该记录(如果不应该，isRecording= false )，在这种情况下，将删除tap并停止audioEngine。否则，将再次调用startRecording()来填充另一个缓冲区。在第二次打开录制按钮之前，我对此没有任何问题。

下面是我的记录按钮的objc函数：

    @objc func recordingState(){
        if isRecording{
            recordButton.setImage(UIImage(named: "unfilled_star.png"), for: .normal)
            isRecording = false
        }
        
        else{
            print("try to start recording")
            recordButton.setImage(UIImage(named: "filled_star.png"), for: .normal)
 
            let speechRecognizer = SFSpeechRecognizer()
            requestDictAccess();
            
            if speechRecognizer!.isAvailable { //if the user has granted permission
                speechRecognizer?.supportsOnDeviceRecognition = true //for offline data
                isRecording = true
                
                recognizeAudioStream()
            }
        }
    }

当第二次运行recognizeAudioStream()时，我得到了这个输出，整个代码块大约在一秒钟内完成：

authorized
2021-04-22 22:38:29.671122-0400 DictoCounter[76126:11539342] [aurioc] 323: Unable to join I/O thread to workgroup ((null)): 2
2021-04-22 22:38:29.679718-0400 DictoCounter[76126:11539130] [Utility] +[AFAggregator logDictationFailedWithError:] Error Domain=kAFAssistantErrorDomain Code=209 "(null)"
completed buffer
2021-04-22 22:38:29.688449-0400 DictoCounter[76126:11538858] Words successfully saved.
2021-04-22 22:38:29.690209-0400 DictoCounter[76126:11539349] [aurioc] 323: Unable to join I/O thread to workgroup ((null)): 2
2021-04-22 22:38:29.699224-0400 DictoCounter[76126:11539130] [Utility] +[AFAggregator logDictationFailedWithError:] Error Domain=kAFAssistantErrorDomain Code=209 "(null)"
completed buffer
2021-04-22 22:38:29.719147-0400 DictoCounter[76126:11538858] Words successfully saved.
2021-04-22 22:38:29.720698-0400 DictoCounter[76126:11539352] [aurioc] 323: Unable to join I/O thread to workgroup ((null)): 2
2021-04-22 22:38:29.734173-0400 DictoCounter[76126:11539102] [Utility] +[AFAggregator logDictationFailedWithError:] Error Domain=kAFAssistantErrorDomain Code=209 "(null)"
completed buffer
2021-04-22 22:38:29.740684-0400 DictoCounter[76126:11538858] Words successfully saved.
2021-04-22 22:38:29.741952-0400 DictoCounter[76126:11539370] [aurioc] 323: Unable to join I/O thread to workgroup ((null)): 2
2021-04-22 22:38:29.754000-0400 DictoCounter[76126:11539102] [Utility] +[AFAggregator logDictationFailedWithError:] Error Domain=kAFAssistantErrorDomain Code=209 "(null)"
completed buffer
2021-04-22 22:38:29.761909-0400 DictoCounter[76126:11538858] Words successfully saved.
2021-04-22 22:38:29.763036-0400 DictoCounter[76126:11539371] [aurioc] 323: Unable to join I/O thread to workgroup ((null)): 2
2021-04-22 22:38:29.776616-0400 DictoCounter[76126:11539104] [Utility] +[AFAggregator logDictationFailedWithError:] Error Domain=kAFAssistantErrorDomain Code=209 "(null)"
completed buffer

我不太确定在这里该做什么。我已经查看了许多其他帖子，这些帖子建议没有删除taps，但我删除了do/catch块中的所有taps。我不确定我在演奏什么。非常感谢大家的帮助--提前谢谢！

Answer 1

可能的问题是路由/配置更改或中断，您可以检查在结束录制时是否调用这些通知中的任何一个

private var notificationTokens = [NSObjectProtocol]()

// init
notificationTokens = [
    NotificationCenter.default.addObserver(
        forName: AVAudioSession.routeChangeNotification,
        object: nil,
        queue: .main
    ) { notification in
        self.engineStartTimer?.invalidate()
        guard self.resumePlaybackAfterSeek == nil else { return }
        self.scheduledBufferFrames = 0
        self.ignoreBufferIndex = self.lastBufferIndex
        self.resumePlaybackAfterSeek = false
        startRestartEngineTimer()
    },
    NotificationCenter.default.addObserver(
        forName: AVAudioSession.interruptionNotification,
        object: nil,
        queue: .main
    ) { notification in
        startRestartEngineTimer()
    },
    NotificationCenter.default.addObserver(
        forName: .AVAudioEngineConfigurationChange,
        object: nil,
        queue: .main
    ) { notification in
        startRestartEngineTimer()
    }
]

如果这不起作用，请提供一个MRE