我可以离线渲染具有动态速度的音频文件吗？

Question

我正在开发一个卡拉OK应用程序。我试着提供一个有趣的功能。我可以使用AudioKit离线渲染基于时间的动态速度值的音频文件吗？点击下面的图片，你很快就会得到它。

image example

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我在这里发布了一些代码。

// I want to change the tempo for bgm audio file dynamically
self.timePitch = AKTimePitch(self.bgmPlayer)
// here I set the initialized rate value to time Pitch
self.timePitch.rate = 1.0
// support iOS10+
self.out = AKOfflineRenderNode()
self.timePitch.connect(to: self.out)
// make the renderer as AudioKit.out
AudioKit.output = self.out
do {
    try AudioKit.start()
} catch {
    debugPrint(error.localizedDescription)
}
let url = URL(fileURLWithPath: NSTemporaryDirectory() + "output.caf")
// get total duration
let duration = self.duration()
DispatchQueue.global(qos: .background).async {
    do {
        let avAudioTime = AVAudioTime(sampleTime: 0, atRate:self.out.avAudioNode.inputFormat(forBus: 0).sampleRate)
        // start play BGM
        self.bgmPlayer.play(at: avAudioTime)
        // and render it to an offline file
        try self.out?.renderToURL(url, duration: duration)
        // **********
        // Question:
        // Can I change the tempo value when rendering?
        // **********

        // stop when finished
        self.bgmPlayer.stop()
    } catch {
        debugPrint(error)
    }
}

Answer 1

这实际上取决于动态速度的实现方式 - 您可以通过时间/音高变换发送音频并渲染结果。