使用 AVAudioPlayer 在 iOS 中自动平移

Posted 2023-03-08

【中文标题】使用 AVAudioPlayer 在 iOS 中自动平移

【英文标题】：Autopan in iOS with AVAudioPlayer smoothly

【发布时间】：2019-11-20 09:02:40

【问题描述】：

我正在尝试使用 AVaudioPlayer 构建自动平移（在左、中、右声道之间移动音频）来播放我的音乐文件。我可以通过 AVAudioPlayer.pan 方法得到它。通过在我的 swift 代码中使用计时器来实现自动平移。现在的问题是，音频播放不流畅，并且介于两者之间。

这是我现在的代码，

class AudioPlayer: UIViewController 
  var player = AVAudioPlayer()

override func viewDidLoad() 
        super.viewDidLoad()
      prepareAudiosession()
    

  func prepareAudioSession() 

           let audioFileName = "LPNumb"
           let audioFileExtension = "mp3"

           guard let filePath = Bundle.main.path(forResource: audioFileName, ofType: audioFileExtension) else 
               print("Audio file not found at specified path")
               return
           
        do 
           let alertSound = URL(fileURLWithPath: filePath)
           try? player = AVAudioPlayer(contentsOf: alertSound)

         catch 
            print(error)
        
       

  @IBAction func play(_ sender: AnyObject)
        player.play()
        if  player.isPlaying
        _ = Timer.scheduledTimer(timeInterval: 0.50, target: self, selector: #selector(self.update1), userInfo: nil, repeats: true)
        _ = Timer.scheduledTimer(timeInterval: 1.0, target: self, selector: #selector(self.update2), userInfo: nil, repeats: true)
            _ = Timer.scheduledTimer(timeInterval: 1.50, target: self, selector: #selector(self.update3), userInfo: nil, repeats: true)
        



    
   @objc func update1() 
        player.pan = 0
     
    @objc func update2() 
        player.pan = 1

    
    @objc func update3() 
        player.pan = -1
    

我想将输出音频设为 MONO，并要求音频能够顺利播放 AUTOPANNED。

【参考方案1】：

我认为，您只需为这项任务制作一个 Timer。查看代码：

import UIKit
import AVFoundation

enum PanState 
    case up
    case down


class ViewController: UIViewController 

    var audioPlayer: AVAudioPlayer?
    var timerForPan: Timer?
    var pan: Double = 0.0
    var panState: PanState = .up

    override func viewDidLoad() 
        super.viewDidLoad()

        if let path = Bundle.main.path(forResource: "LPNumb", ofType: "mp3") 
            let record = URL(fileURLWithPath: path)
            setupRecordToPlayer(from: record)
        
        setTimers()
    

    func setTimers() 
        timerForPan = Timer.scheduledTimer(timeInterval: 1, target: self, selector: #selector(self.updatePan), userInfo: nil, repeats: true)
    

    func setupRecordToPlayer(from url: URL) 
        do 
            audioPlayer = try AVAudioPlayer(contentsOf: url)
         catch let error 
            debugPrint(error.localizedDescription)
        
    

    @IBAction func playButtonPressed(_ sender: UIButton) 
        audioPlayerToPlay()
    

    @objc func updatePan() 
        if audioPlayer?.isPlaying ?? false 
            switch panState 
            case .up:
                self.pan += 0.1
                if pan >= 1 
                    self.panState = .down
                
            case .down:
                self.pan -= 0.1
                if pan <= -1 
                    self.panState = .up
                
            
            audioPlayer?.pan = Float(self.pan)
        
    

    /// Prepare Audio player to play
    func audioPlayerToPlay() 
        audioPlayer?.prepareToPlay()
        do 
            try AVAudioSession.sharedInstance().setCategory(.playback, mode: .default, options: [])
         catch 
            print(error.localizedDescription)
        
        audioPlayer?.play()
    

【讨论】：

,非常感谢。这是执行平移任务的最佳可能性..