iOS：使用 Swift 修剪音频文件？

Posted 2023-02-25

【中文标题】iOS：使用 Swift 修剪音频文件？

【英文标题】：iOS: trimming audio files with Swift?

【发布时间】：2016-11-16 13:55:36

【问题描述】：

我必须合并音频文件和录制的声音。例如录制的声音是 47 秒。我必须将 4 分钟的音频歌曲剪切或修剪为 47 秒。并合并音频文件。

var url:NSURL?
    if self.audioRecorder != nil
    
        url = self.audioRecorder!.url
    

    else
    
        url = self.soundFileURL!

    
    print("playing \(url)")
    do
    
        self.newplayer = try AVPlayer(URL: url!)
        let avAsset = AVURLAsset(URL: url!, options: nil)
        print("\(avAsset)")
        let audioDuration = avAsset.duration
        let totalSeconds = CMTimeGetSeconds(audioDuration)
        let hours = floor(totalSeconds / 3600)
        var minutes = floor(totalSeconds % 3600 / 60)
        var seconds = floor(totalSeconds % 3600 % 60)
        print("hours = \(hours),minutes = \(minutes),seconds = \(seconds)")

这是输出：//hours = 0.0,minutes = 0.0,seconds = 42.0

对于修剪方法，我刚刚尝试过：如何设置确切的持续时间、开始时间和结束时间以及新的网址：

 func exportAsset(asset:AVAsset, fileName:String)

    let documentsDirectory = NSFileManager.defaultManager().URLsForDirectory(.DocumentDirectory, inDomains: .UserDomainMask)[0]
    let trimmedSoundFileURL = documentsDirectory.URLByAppendingPathComponent(fileName)
    print("saving to \(trimmedSoundFileURL!.absoluteString)")

    let filemanager = NSFileManager.defaultManager()
    if filemanager.fileExistsAtPath(trimmedSoundFileURL!.absoluteString!) 
        print("sound exists")
    

    let exporter = AVAssetExportSession(asset: asset, presetName: AVAssetExportPresetAppleM4A)
    exporter!.outputFileType = AVFileTypeAppleM4A
    exporter!.outputURL = trimmedSoundFileURL

    let duration = CMTimeGetSeconds(asset.duration)
    if (duration < 5.0) 
        print("sound is not long enough")
        return
    
    // e.g. the first 5 seconds
    let startTime = CMTimeMake(0, 1)
    let stopTime = CMTimeMake(5, 1)
    let exportTimeRange = CMTimeRangeFromTimeToTime(startTime, stopTime)
    exporter!.timeRange = exportTimeRange


    // do it
    exporter!.exportAsynchronouslyWithCompletionHandler(
        switch exporter!.status 
        case  AVAssetExportSessionStatus.Failed:
            print("export failed \(exporter!.error)")
        case AVAssetExportSessionStatus.Cancelled:
            print("export cancelled \(exporter!.error)")
        default:
            print("export complete")
        
    )

【参考方案1】：

我终于找到了我的问题的答案。它工作正常...我附上了下面的代码。我在其中添加了修剪音频代码。它对那些试图合并和修剪音频的人很有用（swift2.3）：

func mixAudio()

    let currentTime = CFAbsoluteTimeGetCurrent()
    let composition = AVMutableComposition()
    let compositionAudioTrack = composition.addMutableTrackWithMediaType(AVMediaTypeAudio, preferredTrackID: kCMPersistentTrackID_Invalid)
    compositionAudioTrack.preferredVolume = 0.8
    let avAsset = AVURLAsset.init(URL: soundFileURL, options: nil)
    print("\(avAsset)")
    var tracks = avAsset.tracksWithMediaType(AVMediaTypeAudio)
    let clipAudioTrack = tracks[0]
    do 
        try compositionAudioTrack.insertTimeRange(CMTimeRangeMake(kCMTimeZero, avAsset.duration), ofTrack: clipAudioTrack, atTime: kCMTimeZero)
    
    catch _ 
    
    let compositionAudioTrack1 = composition.addMutableTrackWithMediaType(AVMediaTypeAudio, preferredTrackID: kCMPersistentTrackID_Invalid)
    compositionAudioTrack.preferredVolume = 0.8

    let avAsset1 = AVURLAsset.init(URL: soundFileURL1)
    print(avAsset1)


    var tracks1 = avAsset1.tracksWithMediaType(AVMediaTypeAudio)
    let clipAudioTrack1 = tracks1[0]
    do 
        try compositionAudioTrack1.insertTimeRange(CMTimeRangeMake(kCMTimeZero, avAsset1.duration), ofTrack: clipAudioTrack1, atTime: kCMTimeZero)
    
    catch _ 
    
    var paths = NSSearchPathForDirectoriesInDomains(.LibraryDirectory, .UserDomainMask, true)
    let CachesDirectory = paths[0]
    let strOutputFilePath = CachesDirectory.stringByAppendingString("/Fav")
    print(" strOutputFilePath is \n \(strOutputFilePath)")

    let requiredOutputPath = CachesDirectory.stringByAppendingString("/Fav.m4a")
    print(" requiredOutputPath is \n \(requiredOutputPath)")

    soundFile1 = NSURL.fileURLWithPath(requiredOutputPath)
    print(" OUtput path is \n \(soundFile1)")
    var audioDuration = avAsset.duration
    var totalSeconds = CMTimeGetSeconds(audioDuration)
    var hours = floor(totalSeconds / 3600)
    var minutes = floor(totalSeconds % 3600 / 60)
    var seconds = Int64(totalSeconds % 3600 % 60)
    print("hours = \(hours), minutes = \(minutes), seconds = \(seconds)")

    let recordSettings:[String : AnyObject] = [

        AVFormatIDKey: Int(kAudioFormatMPEG4AAC),
        AVSampleRateKey: 12000,
        AVNumberOfChannelsKey: 1,
        AVEncoderAudioQualityKey: AVAudioQuality.Low.rawValue
    ]
    do 
        audioRecorder = try AVAudioRecorder(URL: soundFile1, settings: recordSettings)
        audioRecorder!.delegate = self
        audioRecorder!.meteringEnabled = true
        audioRecorder!.prepareToRecord()
    

    catch let error as NSError
    
        audioRecorder = nil
        print(error.localizedDescription)
    

    do 

        try NSFileManager.defaultManager().removeItemAtURL(soundFile1)
    
    catch _ 
    
    let exporter = AVAssetExportSession(asset: composition, presetName: AVAssetExportPresetAppleM4A)
    exporter!.outputURL = soundFile1
    exporter!.outputFileType = AVFileTypeAppleM4A
    let duration = CMTimeGetSeconds(avAsset1.duration)
    print(duration)
    if (duration < 5.0) 
        print("sound is not long enough")
        return
    
    // e.g. the first 30 seconds
    let startTime = CMTimeMake(0, 1)
    let stopTime = CMTimeMake(seconds,1)
    let exportTimeRange = CMTimeRangeFromTimeToTime(startTime, stopTime)
    print(exportTimeRange)
    exporter!.timeRange = exportTimeRange
    print(exporter!.timeRange)


    exporter!.exportAsynchronouslyWithCompletionHandler
        () -> Void in
            print(" OUtput path is \n \(requiredOutputPath)")
            print("export complete: \(CFAbsoluteTimeGetCurrent() - currentTime)")
            var url:NSURL?
            if self.audioRecorder != nil
            
                url = self.audioRecorder!.url
            

            else
            
                url = self.soundFile1!
                print(url)

            

            print("playing \(url)")

    do
    
        print(self.soundFile1)
        print(" OUtput path is \n \(requiredOutputPath)")
        self.setSessionPlayback()
        do 
                                        self.optData = try NSData(contentsOfURL: self.soundFile1!, options: NSDataReadingOptions.DataReadingMappedIfSafe)
                                        print(self.optData)
                                        self.recordencryption = self.optData.base64EncodedStringWithOptions(NSDataBase64EncodingOptions())

                                        //  print(self.recordencryption)
                                          self.myImageUploadRequest()


                                    



        self.wasteplayer = try AVAudioPlayer(contentsOfURL: self.soundFile1)
        self.wasteplayer.numberOfLoops = 0
        self.wasteplayer.play()


    

    catch _
    
    

    

【讨论】：

这个函数中还用到了类级别的变量，请问您能评论一下哪些变量用于什么目的？ @HariKarthick

【参考方案2】：

基于上一个答案简单的声音修剪功能。

     static func trimmSound( inUrl:URL, outUrl:URL,timeRange:CMTimeRange, callBack:@escaping () -> Void)
          
          let startTime = timeRange.start
          let duration = timeRange.duration
          let audioAsset = AVAsset(url: inUrl)
          let composition = AVMutableComposition()
          let compositionAudioTrack = composition.addMutableTrack(withMediaType: AVMediaType.audio, preferredTrackID: CMPersistentTrackID(kCMPersistentTrackID_Invalid))
          
          let sourceAudioTrack = audioAsset.tracks(withMediaType: AVMediaType.audio).first!
          do 
               try compositionAudioTrack?.insertTimeRange(CMTimeRangeMake(start: startTime, duration: duration), of: sourceAudioTrack, at: .zero)
               
           catch 
               print(error.localizedDescription)
               return
          
          let exporter = AVAssetExportSession(asset: composition, presetName: AVAssetExportPresetAppleM4A)
          exporter!.outputURL = outUrl
          exporter!.outputFileType = AVFileType.m4a
          exporter!.shouldOptimizeForNetworkUse = true
          exporter!.exportAsynchronously 
               DispatchQueue.main.async 
                    callBack()