MPmovieplayercontroller音频问题

Question

我正在创建简单的媒体播放器我的问题是当我点击下一个按钮然后视频更改但之前视频的声音在新视频中播放3-4秒然后声音改变

这是我的代码

播放视频代码

Cross Distances

下一个按钮代码

func startplaying()
{
  if a >= 0 && a <= arr.count - 1
  {
    println(a)
    filesArray  = NSFileManager.defaultManager().contentsOfDirectoryAtPath(fileDestination, error: nil)!
    var predicate = NSPredicate(format: "self ENDSWITH '.mp4'", filesArray)
    filesArray = filesArray.filteredArrayUsingPredicate(predicate)
    videoPath = fileDestination.stringByAppendingPathComponent(arr[a])
    videoPath = "file://".stringByAppendingPathComponent(videoPath)
    println(arr[a])
    videoPath = Utilities.Instance().urlEncoder(videoPath)

    let url =  NSURL(string: videoPath)

    movieplayer = MPMoviePlayerController(contentURL: url)
    // navigationItem.title = name
    titleLabel.text = arr[a]
    navigationItem.hidesBackButton = true
    movieplayer.view.frame = CGRect(x: 0, y: 0, width: view.frame.size.width, height: view.frame.size.height)
    movieplayer.view.sizeToFit()
    movieplayer.fullscreen = true
    movieplayer.scalingMode = MPMovieScalingMode.AspectFit
    movieplayer.fullscreen = true
    movieplayer.controlStyle = MPMovieControlStyle.None
    movieplayer.movieSourceType = MPMovieSourceType.File
    movieplayer.play()
    slider.value = 0
    slider.maximumValue = Float(movieplayer.duration)
    timer = NSTimer.scheduledTimerWithTimeInterval(1, target: self, selector: "updateTime", userInfo: nil, repeats: true)
    self.view.addSubview(movieplayer.view)
    self.view.addSubview(butView)
    self.view.addSubview(titleView)
   }
}