使用 AVAudioEngine 重复播放音频文件

Posted 2023-02-15

【中文标题】使用 AVAudioEngine 重复播放音频文件

【英文标题】：Playing an audio file repeatedly with AVAudioEngine

【发布时间】：2015-04-15 15:10:09

【问题描述】：

我正在使用 Swift 和 Xcode 6 开发 ios 应用程序。我想做的是使用 AVAudioEngine 播放音频文件，直到此时一切正常。但是我怎样才能不停地播放它，我的意思是，当它结束时它又重新开始呢？

这是我的代码：

/*==================== CONFIGURATES THE AVAUDIOENGINE ===========*/
    audioEngine.reset() //Resets any previous configuration on AudioEngine

    let audioPlayerNode = AVAudioPlayerNode() //The node that will play the actual sound
    audioEngine.attachNode(audioPlayerNode) //Attachs the node to the audioengine

    audioEngine.connect(audioPlayerNode, to: audioEngine.outputNode, format: nil) //Connects the applause playback node to the sound output
    audioPlayerNode.scheduleFile(applause.applauseFile, atTime: nil, completionHandler: nil)

    audioEngine.startAndReturnError(nil)
    audioPlayerNode.play() //Plays the sound

在我说我应该为此使用 AVAudioPlayer 之前，我不能，因为以后我将不得不使用一些效果并同时播放三个音频文件，还要重复播放。

【参考方案1】：

我在另一个问题中找到了解决方案，@CarveDrone 提出并自动回答了这个问题，所以我刚刚复制了他使用的代码：

class aboutViewController: UIViewController 


    var audioEngine: AVAudioEngine = AVAudioEngine()
    var audioFilePlayer: AVAudioPlayerNode = AVAudioPlayerNode()

    override func viewDidLoad() 
        super.viewDidLoad()
        // Do any additional setup after loading the view, typically from a nib.


        let filePath: String = NSBundle.mainBundle().pathForResource("chimes", ofType: "wav")!
        println("\(filePath)")
        let fileURL: NSURL = NSURL(fileURLWithPath: filePath)!
        let audioFile = AVAudioFile(forReading: fileURL, error: nil)
        let audioFormat = audioFile.processingFormat
        let audioFrameCount = UInt32(audioFile.length)
        let audioFileBuffer = AVAudioPCMBuffer(PCMFormat: audioFormat, frameCapacity: audioFrameCount)
        audioFile.readIntoBuffer(audioFileBuffer, error: nil)

        var mainMixer = audioEngine.mainMixerNode
        audioEngine.attachNode(audioFilePlayer)
        audioEngine.connect(audioFilePlayer, to:mainMixer, format: audioFileBuffer.format)
        audioEngine.startAndReturnError(nil)

        audioFilePlayer.play()
        audioFilePlayer.scheduleBuffer(audioFileBuffer, atTime: nil, options:.Loops, completionHandler: nil)
    

您唯一需要更改的是filePath 常量。这是原始答案的链接：Having AVAudioEngine repeat a sound

【讨论】：

请注意，将长文件读入缓冲区将需要很长时间才能加载。 scheduleFile 方法有效地将文件流式传输到播放器，立即开始。不幸的是它没有循环。

嗯，我刚刚将这段代码翻译成 Swift 5，但我在控制台中得到了沉默和几个 kAudioUnitErr_TooManyFramesToProcess...

【参考方案2】：

Swift 5，感谢@Guillermo Barreiro

    var audioEngine: AVAudioEngine = AVAudioEngine()
    var audioFilePlayer: AVAudioPlayerNode = AVAudioPlayerNode()

    override func viewDidLoad() 
        super. viewDidLoad()

        guard let filePath: String = Bundle.main.path(forResource: "chimes", ofType: "wav") else return 
        print("\(filePath)")
        let fileURL: URL = URL(fileURLWithPath: filePath)
        guard let audioFile = try? AVAudioFile(forReading: fileURL) else return 

        let audioFormat = audioFile.processingFormat
        let audioFrameCount = UInt32(audioFile.length)
        guard let audioFileBuffer = AVAudioPCMBuffer(pcmFormat: audioFormat, frameCapacity: audioFrameCount)  else return 
        do
            try audioFile.read(into: audioFileBuffer)
         catch
            print("over")
        
        let mainMixer = audioEngine.mainMixerNode
        audioEngine.attach(audioFilePlayer)
        audioEngine.connect(audioFilePlayer, to:mainMixer, format: audioFileBuffer.format)
        try? audioEngine.start()
        audioFilePlayer.play()
        audioFilePlayer.scheduleBuffer(audioFileBuffer, at: nil, options:AVAudioPlayerNodeBufferOptions.loops)