Apple's New AudioEngine for Pitch Change

  1. 4 years ago
    Edited 4 years ago by niutech

    I am currently trying to get Apple's new audio engine working with my current audio setup. Specifically, I am trying to change the pitch with Audio Engine, which apparently is possible according to this post .

    I have also looked into other pitch changing solutions including Dirac and ObjectAL, but unfortunately both seem to be pretty messed up in terms of working with Swift, which I am using.

    My question is how do I change the pitch of an audio file using Apple's new audio engine. I am able to play sounds using AVAudioPlayer, but I am not getting how the file is referenced in audioEngine. In the code on the linked page there is a 'format' that refers to audio file, but I am not getting how to create a format, or what it does.

    I am playing sounds with this simple code:

    let path = NSBundle.mainBundle().pathForResource(String(randomNumber), ofType:"m4r")
    let fileURL = NSURL(fileURLWithPath: path!)
    player = AVAudioPlayer(contentsOfURL: fileURL, error: nil)
    player.prepareToPlay()
    player.play()

  2. niutech

    25 Sep 2014 Administrator
    Edited 4 years ago by niutech

    Gene De Lisa replied on StackOverflow:

    You use an AVAudioPlayerNode, not an AVAudioPlayer.

    engine = AVAudioEngine()
    playerNode = AVAudioPlayerNode()
    engine.attachNode(playerNode)


    Then you can attach an AVAudioUnitTimePitch.

    auTimePitch = AVAudioUnitTimePitch()
    auTimePitch.pitch = 1200 // In cents. The default value is 1.0. The range of values is -2400 to 2400
    auTimePitch.rate = 2 //The default value is 1.0. The range of supported values is 1/32 to 32.0.
    engine.attachNode(auTimePitch)
    engine.connect(playerNode, to: auTimePitch, format: mixer.outputFormatForBus(0))
    engine.connect(auTimePitch, to: mixer, format: mixer.outputFormatForBus(0))

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