如何将音频效果应用于文件并写入文件系统 – iOS

我正在构建一个应用程序,允许用户将音频过滤器应用于录制的音频,例如Reverb,Boost.

我无法找到有关如何将过滤器应用于文件本身的任何可行信息来源,因为以后需要将处理后的文件上传到服务器.

我目前正在使用AudioKit进行可视化,我知道它能够进行音频处理,但仅限于播放.请提供任何进一步研究的建议.

解决方法

AudioKit有一个不需要iOS 11的离线渲染节点.这是一个例子,需要player.schedule(…)和player.start(at.)位,因为AKAudioPlayer的底层AVAudioPlayerNode将阻塞调用线程等待如果你用player.play()启动它,那么下一个渲染.

import UIKit
import AudioKit

class ViewController: UIViewController {

    var player: AKAudioPlayer?
    var reverb = AKReverb()
    var boost = AKBooster()
    var offlineRender = AKOfflineRenderNode()

    override func viewDidLoad() {
        super.viewDidLoad()

        guard let url = Bundle.main.url(forResource: "theFunkiestFunkingFunk",withExtension: "mp3") else {
            return
        }
        var audioFile: AKAudioFile?
        do {
            audioFile = try AKAudioFile.init(forReading: url)
            player = try AKAudioPlayer.init(file: audioFile!)
        } catch {
            print(error)
            return
        }
        guard let player = player else {
            return
        }


        player >>> reverb >>> boost >>> offlineRender

        AudioKit.output = offlineRender
        AudioKit.start()


        let docs = FileManager.default.urls(for: .documentDirectory,in: .userDomainMask).first!
        let dstURL = docs.appendingPathComponent("rendered.caf")

        offlineRender.internalRenderEnabled = false
        player.schedule(from: 0,to: player.duration,avTime: nil)
        let sampleTimeZero = AVAudioTime(sampleTime: 0,atRate: AudioKit.format.sampleRate)
        player.play(at: sampleTimeZero)
        do {
            try offlineRender.renderToURL(dstURL,seconds: player.duration)
        } catch {
            print(error)
            return
        }
        offlineRender.internalRenderEnabled = true

        print("Done! Rendered to " + dstURL.path)
    }
}