在Swift中串联两个音频文件并播放它们

Question

我尝试快速连接.wav音频文件。

这是我的代码：

func merge(audio1: NSURL, audio2:  NSURL) {


    var error:NSError?

    var ok1 = false
    var ok2 = false


    var documentsDirectory:String = paths[0] as! String

    //Create AVMutableComposition Object.This object will hold our multiple AVMutableCompositionTrack.
    var composition = AVMutableComposition()
    var compositionAudioTrack1:AVMutableCompositionTrack = composition.addMutableTrackWithMediaType(AVMediaTypeAudio, preferredTrackID: CMPersistentTrackID())
    var compositionAudioTrack2:AVMutableCompositionTrack = composition.addMutableTrackWithMediaType(AVMediaTypeAudio, preferredTrackID: CMPersistentTrackID())

    //create new file to receive data
    var documentDirectoryURL = NSFileManager.defaultManager().URLsForDirectory(.DocumentDirectory, inDomains: .UserDomainMask).first! as! NSURL
    var fileDestinationUrl = documentDirectoryURL.URLByAppendingPathComponent("resultmerge.wav")
    println(fileDestinationUrl)


    var url1 = audio1
    var url2 = audio2


    var avAsset1 = AVURLAsset(URL: url1, options: nil)
    var avAsset2 = AVURLAsset(URL: url2, options: nil)

    var tracks1 =  avAsset1.tracksWithMediaType(AVMediaTypeAudio)
    var tracks2 =  avAsset2.tracksWithMediaType(AVMediaTypeAudio)

    var assetTrack1:AVAssetTrack = tracks1[0] as! AVAssetTrack
    var assetTrack2:AVAssetTrack = tracks2[0] as! AVAssetTrack


    var duration1: CMTime = assetTrack1.timeRange.duration
    var duration2: CMTime = assetTrack2.timeRange.duration

    var timeRange1 = CMTimeRangeMake(kCMTimeZero, duration1)
    var timeRange2 = CMTimeRangeMake(duration1, duration2)


    ok1 = compositionAudioTrack1.insertTimeRange(timeRange1, ofTrack: assetTrack1, atTime: kCMTimeZero, error: nil)
    if ok1 {

        ok2 = compositionAudioTrack2.insertTimeRange(timeRange2, ofTrack: assetTrack2, atTime: duration1, error: nil)

        if ok2 {
            println("success")
        }
    }

    //AVAssetExportPresetPassthrough => concatenation
    var assetExport = AVAssetExportSession(asset: composition, presetName: AVAssetExportPresetPassthrough)
    assetExport.outputFileType = AVFileTypeWAVE
    assetExport.outputURL = fileDestinationUrl
    assetExport.exportAsynchronouslyWithCompletionHandler({
        html" target="_blank">switch assetExport.status{
        case  AVAssetExportSessionStatus.Failed:
            println("failed \(assetExport.error)")
        case AVAssetExportSessionStatus.Cancelled:
            println("cancelled \(assetExport.error)")
        default:
            println("complete")
            var audioPlayer = AVAudioPlayer()
            audioPlayer = AVAudioPlayer(contentsOfURL: fileDestinationUrl, error: nil)
            audioPlayer.prepareToPlay()
            audioPlayer.play()
        }

    })

}

并在终端中运行此错误（在iPhone上运行）：

文件：///var/mobile/Containers/Data/Application/3F49D360-B363-4600-B3BB-
EE0810501910/Documents/resultmerge.wav

成功

失败，错误域= AVFoundationErrorDomain代码= -11838“操作中断” UserInfo = 0x174269ac0
{NSLocalizedDescription =操作中断，NSLocalizedFailureReason =希望操作的内容可以连续多次获得。}

但我不知道为什么会收到此错误。我将不胜感激您可以给我的任何帮助:)

Answer 1

我通过更改两件事使您的代码工作：

• 预设名称：从AVAssetExportPresetPassthrough到AVAssetExportPresetAppleM4A

• 输出文件类型：从AVFileTypeWAVE到 AVFileTypeAppleM4A

assetExport像这样修改您的声明：

var assetExport = AVAssetExportSession(asset: composition, presetName: AVAssetExportPresetAppleM4A)
assetExport.outputFileType = AVFileTypeAppleM4A

那么它将正确合并文件。

看起来AVAssetExportSession仅导出M4A格式，而忽略其他预设。尽管我还没有探讨过这种可能性，但也许有一种方法可以使其导出其他格式（通过对它进行子类化？）。