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Я пытаюсь зациклить mp3-файл, где я могу изменить его высоту во время воспроизведения. Я могу изменить высоту тона, но я не могу зациклить файл. Это мой код:

 import AVKit

class ViewController: UIViewController {

    @IBOutlet weak var speedSlider: UISlider!
    @IBOutlet weak var speedLabel: UILabel!
    let pitchControl = AVAudioUnitTimePitch()
    let engine = AVAudioEngine()
    
    override func viewDidLoad(){
        super.viewDidLoad()
        do{ try playSound(soundName: "audiSound1")} catch{}
    }

    @IBAction func speedSlided(_ sender: Any) {
        pitchControl.pitch = speedSlider.value
        speedLabel.text = String(speedSlider.value)
    }
    
    func playSound(soundName: String) throws{
        guard let url = Bundle.main.url(forResource: soundName, withExtension: "mp3") else { return }
        let file = try AVAudioFile(forReading: url)
        let audioPlayer = AVAudioPlayerNode()
        engine.attach(audioPlayer)
        engine.attach(pitchControl)
        engine.connect(audioPlayer, to: pitchControl, format: nil)
        engine.connect(pitchControl, to: engine.mainMixerNode, format: nil)
        audioPlayer.scheduleFile(try! AVAudioFile(forReading: url), at: nil)
        try engine.start()
        audioPlayer.play()
    }
}
 

Чтобы сделать его циклическим, я попытался использовать AVAudioPCMBuffer(), см.:

 import AVKit

class ViewController: UIViewController {

    @IBOutlet weak var speedSlider: UISlider!
    @IBOutlet weak var speedLabel: UILabel!
    let pitchControl = AVAudioUnitTimePitch()
    let engine = AVAudioEngine()
    
    override func viewDidLoad(){
        super.viewDidLoad()
        do{ try playSound(soundName: "audiSound1")} catch{}
    }

    @IBAction func speedSlided(_ sender: Any) {
        pitchControl.pitch = speedSlider.value
        speedLabel.text = String(speedSlider.value)
    }
    
    func playSound(soundName: String) throws{
        guard let url = Bundle.main.url(forResource: soundName, withExtension: "mp3") else { return }
        let file = try AVAudioFile(forReading: url)
        let audioPlayer = AVAudioPlayerNode()
        
        //New:
        let audioFileBuffer = AVAudioPCMBuffer(pcmFormat: file.fileFormat, frameCapacity: AVAudioFrameCount(file.length))
        try? file.read(into: audioFileBuffer!)

        engine.attach(audioPlayer)
        engine.attach(pitchControl)
        engine.connect(audioPlayer, to: pitchControl, format: nil)
        engine.connect(pitchControl, to: engine.mainMixerNode, format: nil)
        audioPlayer.scheduleBuffer(audioFileBuffer!,at: nil, options: .loops, completionHandler: nil) //Changed
        try engine.start()
        audioPlayer.play()
    }
}
 

Но когда я запускаю проект, он выдает мне поток 1: «требуемое условие ложно: isPCMFormat» Ошибка :/ Точное сообщение об ошибке:

2021-04-06 20:31:51.824454 0200 avas[67546:8825321] [avae] AVAEInternal.h:76 требуемое условие ложно: [AVAudioBuffer.мм:175:-[AVAudioPCMBuffer initWithPCMFormat:Емкость кадра:]: (isPCMFormat)] 2021-04-06 20:31:51.832637 0200 avas[67546:8825321] *** Завершение работы приложения из-за неучтенного исключения «com.apple.coreaudio.avfaudio», причина: «требуемое условие ложно: isPCMFormat»

Я понятия не имею, как я могу сделать это другим (рабочим) способом. Кто-нибудь может мне помочь? 🙂

Большое вам спасибо!

Это работает:

 import AVKit

class ViewController: UIViewController {

    @IBOutlet weak var speedSlider: UISlider!
    @IBOutlet weak var speedLabel: UILabel!
    let pitchControl = AVAudioUnitTimePitch()
    let engine = AVAudioEngine()
    
    override func viewDidLoad(){
        super.viewDidLoad()
        do{ try playSound(soundName: "audiSound1")} catch{}
    }

    @IBAction func speedSlided(_ sender: Any) {
        pitchControl.pitch = speedSlider.value
        speedLabel.text = String(speedSlider.value)
    }
    
    func playSound(soundName: String) throws{
        guard let url = Bundle.main.url(forResource: soundName, withExtension: "mp3") else { return }
        let file = try AVAudioFile(forReading: url)
        let audioPlayer = AVAudioPlayerNode()
        let audioFormat = file.processingFormat
        let audioFrameCount = UInt32(file.length)
        let audioFileBuffer = AVAudioPCMBuffer(pcmFormat: audioFormat, frameCapacity: audioFrameCount)
        
        try! file.read(into: audioFileBuffer!)
        let mainMixer = engine.mainMixerNode
        
        engine.attach(audioPlayer)
        engine.attach(pitchControl)
        engine.connect(audioPlayer, to: mainMixer, format: audioFileBuffer?.format)
        engine.connect(audioPlayer, to: pitchControl, format:audioFileBuffer?.format)
        engine.connect(pitchControl, to: engine.mainMixerNode, format: nil)
        
        try engine.start()
        audioPlayer.play()
        audioPlayer.scheduleBuffer(audioFileBuffer!, at: nil, options: .loops, completionHandler: nil)
    }
}