Avspeechrecognizer: Required Condition Is False: _Recordingtap == Nil Error in Swift3

AVAudioSequencer Causes Crash on Deinit/Segue: 'required condition is false: outputNode'

This crash can be confusing, and may also output no error message whatsoever to the console if the sequencer's content hasn't been loaded yet. Very unhelpful!

The AVAudioSequencer is indeed the cause of the issue. To fix it, make the sequencer an implicitly unwrapped optional (i.e. add ! to its type) and add explicit instructions to stop & remove it during deinit, before the rest of the object is deinitialized.

The fixed code is as follows (take note of the deinit method especially):

class TestAudioClass {

    private var audioEngine: AVAudioEngine
    private var sampler: AVAudioUnitSampler
    private var sequencer: AVAudioSequencer!

    init() {
        self.audioEngine = AVAudioEngine()
        self.sampler = AVAudioUnitSampler()
        audioEngine.attach(sampler)
        audioEngine.connect(sampler, to: audioEngine.mainMixerNode, format: nil)
        self.sequencer = AVAudioSequencer(audioEngine: audioEngine)
        if let fileURL = Bundle.main.url(forResource: "TestMusic", withExtension: "mid") {
            do {
                try sequencer.load(from: fileURL, options: AVMusicSequenceLoadOptions())
            } catch {
                print("Error loading sequencer: \(error.localizedDescription)")
            }
        }
        sequencer.prepareToPlay()
    }

    deinit {
        sequencer.stop()
        sequencer = nil
    }
}

Hope this helps!

Tap audio output using AVAudioEngine

I was facing the same problem and during 2 days of brainstorming found the following.

Apple says that For AVAudioOutputNode, tap format must be specified as nil. I'm not sure that it's important but in my case, that finally worked, format was nil.
You need to start recording and don't forget to stop it.

Removing tap is really important, otherwise you will have file that you can't open.

Try to save the file with the same audio settings that you used in source file.

Here's my code that finally worked. It was partly taken from this question Saving Audio After Effect in iOS.

    func playSound() {
    let rate: Float? = effect.speed
    let pitch: Float? = effect.pitch
    let echo: Bool? = effect.echo
    let reverb: Bool? = effect.reverb

    // initialize audio engine components
    audioEngine = AVAudioEngine()

    // node for playing audio
    audioPlayerNode = AVAudioPlayerNode()
    audioEngine.attach(audioPlayerNode)

    // node for adjusting rate/pitch
    let changeRatePitchNode = AVAudioUnitTimePitch()
    if let pitch = pitch {
        changeRatePitchNode.pitch = pitch
    }
    if let rate = rate {
        changeRatePitchNode.rate = rate
    }
    audioEngine.attach(changeRatePitchNode)

    // node for echo
    let echoNode = AVAudioUnitDistortion()
    echoNode.loadFactoryPreset(.multiEcho1)
    audioEngine.attach(echoNode)

    // node for reverb
    let reverbNode = AVAudioUnitReverb()
    reverbNode.loadFactoryPreset(.cathedral)
    reverbNode.wetDryMix = 50
    audioEngine.attach(reverbNode)

    // connect nodes
    if echo == true && reverb == true {
        connectAudioNodes(audioPlayerNode, changeRatePitchNode, echoNode, reverbNode, audioEngine.mainMixerNode, audioEngine.outputNode)
    } else if echo == true {
        connectAudioNodes(audioPlayerNode, changeRatePitchNode, echoNode, audioEngine.mainMixerNode, audioEngine.outputNode)
    } else if reverb == true {
        connectAudioNodes(audioPlayerNode, changeRatePitchNode, reverbNode, audioEngine.mainMixerNode, audioEngine.outputNode)
    } else {
        connectAudioNodes(audioPlayerNode, changeRatePitchNode, audioEngine.mainMixerNode, audioEngine.outputNode)
    }

    // schedule to play and start the engine!
    audioPlayerNode.stop()
    audioPlayerNode.scheduleFile(audioFile, at: nil) {
        var delayInSeconds: Double = 0
        if let lastRenderTime = self.audioPlayerNode.lastRenderTime, let playerTime = self.audioPlayerNode.playerTime(forNodeTime: lastRenderTime) {
            if let rate = rate {
                delayInSeconds = Double(self.audioFile.length - playerTime.sampleTime) / Double(self.audioFile.processingFormat.sampleRate) / Double(rate)
            } else {
                delayInSeconds = Double(self.audioFile.length - playerTime.sampleTime) / Double(self.audioFile.processingFormat.sampleRate)
            }
        }

        // schedule a stop timer for when audio finishes playing
        self.stopTimer = Timer(timeInterval: delayInSeconds, target: self, selector: #selector(EditViewController.stopAudio), userInfo: nil, repeats: false)
        RunLoop.main.add(self.stopTimer!, forMode: RunLoop.Mode.default)
    }

    do {
        try audioEngine.start()
    } catch {
        showAlert(Alerts.AudioEngineError, message: String(describing: error))
        return
    }

    //Try to save
    let dirPaths: String = (NSSearchPathForDirectoriesInDomains(.libraryDirectory, .userDomainMask, true)[0]) + "/sounds/"
    let tmpFileUrl = URL(fileURLWithPath: dirPaths + "effected.caf")

    //Save the tmpFileUrl into global varibale to not lose it (not important if you want to do something else)
    filteredOutputURL = URL(fileURLWithPath: filePath)
        do{
            print(dirPaths)
            let settings = [AVSampleRateKey : NSNumber(value: Float(44100.0)),
            AVFormatIDKey : NSNumber(value: Int32(kAudioFormatMPEG4AAC)),
            AVNumberOfChannelsKey : NSNumber(value: 1),
            AVEncoderAudioQualityKey : NSNumber(value: Int32(AVAudioQuality.medium.rawValue))]
            self.newAudio = try! AVAudioFile(forWriting: tmpFileUrl as URL, settings: settings)
            let length = self.audioFile.length
            audioEngine.mainMixerNode.installTap(onBus: 0, bufferSize: 4096, format: nil) {
                (buffer: AVAudioPCMBuffer?, time: AVAudioTime!) -> Void in
                //Let us know when to stop saving the file, otherwise saving infinitely
                if (self.newAudio.length) <= length {
                    do{
                        try self.newAudio.write(from: buffer!)

                    } catch _{
                        print("Problem Writing Buffer")
                    }
                } else {
                    //if we dont remove it, will keep on tapping infinitely
                    self.audioEngine.mainMixerNode.removeTap(onBus: 0)
                }
            }
    }

    // play the recording!
    audioPlayerNode.play()

}

@objc func stopAudio() {
    if let audioPlayerNode = audioPlayerNode {
        let engine = audioEngine
        audioPlayerNode.stop()
        engine?.mainMixerNode.removeTap(onBus: 0)

    }
    if let stopTimer = stopTimer {
        stopTimer.invalidate()
    }
    configureUI(.notPlaying)
    if let audioEngine = audioEngine {
        audioEngine.stop()
        audioEngine.reset()
    }
    isPlaying = false
}

Related Topics