iOS: trimming audio files with Swift?

问题

I have to merge the audio file and recorded voice.For example the recorded voice is 47seconds. I have to cut or trim the 4minutes audio song to 47seconds. And merge the audio file.

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)")}

This is the output: //hours = 0.0,minutes = 0.0,seconds = 42.0

For trim method i just tried this: How to set exact Duration,start time and end time and the new url :

 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")
        }
    })
}

回答1:

Finally I find the answer for my question.It's working fine...I attached the code below. I added the trim audio code in it.It will be useful for those who are trying to merge and trim the audio(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 _
    {
    }

    }
}

来源：https://stackoverflow.com/questions/40633969/ios-trimming-audio-files-with-swift