AudioKit ios AKSamplerMetronome

Question

AudioKit ios AKSamplerMetronome

4

我目前正在使用AudioKit的AKSamplerMetronome来生成和播放节拍器声音，现在我需要实现一个回调函数来获取当前节拍，假设我有5个节拍，我需要获取当前正在播放的节拍，以便我可以根据节拍计数添加一些更多的功能。是否有可用的回调函数来实现它？？

这是我的当前代码：

 // using AKSamplerMetronome
var metronome1 = AKSamplerMetronome()
var mixer = AKMixer()
// first sound called
let beatstart = Bundle.main.url(forResource: "mybeat", withExtension: "wav")
 // other sounds based on beat count
let beaten = Bundle.main.url(forResource: "others", withExtension: "wav")
// setting first sound and other beat sounds
metronome1.sound = McountSoundUrl
metronome1.downBeatSound = MoneSoundUrl
metronome1 >>> mixer
AudioKit.output = mixer
AudioKit.start()

- RAM

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- c_booth · Accepted Answer

您可以使用AKSequencer轻松完成此操作（我曾经做过类似的事情）。我将序列器的一个轨道分配给了AKMIDISampler，用于生成节拍声音，并将第二个轨道发送到AKCallbackInstrument中。
在发送到AKCallbackInstrument的轨道中，我随意编码了MIDI数据中的节拍信息，例如，第一拍的MIDI数据具有MIDINote 1，第二拍具有MIDINote 2（您可以使用velocity完成此操作）。然后，回调函数将只查看所有noteOn消息，并从MIDI Note编号获取当前拍子，并相应地进行响应。这有点间接，但它有效。

// create the sequencer before hand (e.g., at init); calling play() immediately after creating it causes some odd behaviour
    let sequencer = AKSequencer()

    // set up the sampler and callbackInst
    let sampler = AKSynthSnare()
    // or for your own sample:
    // let sampler = AKMIDISampler()
    // sampler.loadWav("myMetronomeSound)
    let callbackInst = AKCallbackInstrument()
    AudioKit.output = sampler
    AudioKit.start()

    // create two tracks for the sequencer
    let metronomeTrack = sequencer.newTrack()
    metronomeTrack?.setMIDIOutput(sampler.midiIn)
    let callbackTrack = sequencer.newTrack()
    callbackTrack?.setMIDIOutput(callbackInst.midiIn)

    // create the MIDI data
    for i in 0 ..< 4 {
        // this will trigger the sampler on the four down beats
        metronomeTrack?.add(noteNumber: 60, velocity: 100, position: AKDuration(beats: Double(i)), duration: AKDuration(beats: 0.5))

        // set the midiNote number to the current beat number
        callbackTrack?.add(noteNumber: MIDINoteNumber(i), velocity: 100, position: AKDuration(beats: Double(i)), duration: AKDuration(beats: 0.5))
    }

    // set the callback
    callbackInst.callback = {status, noteNumber, velocity in
        guard status == .noteOn else { return }
        print("beat number: \(noteNumber + 1)")
        // e.g., resondToBeat(beatNum: noteNumber)
    }

    // get the sequencer ready
    sequencer.enableLooping(AKDuration(beats: 4))
    sequencer.setTempo(60)
    sequencer.play()