Question

我正在尝试将一个录像带和两个录像带与AVComposition结合起来。它工作正常（我有一些带有两个录音带的视频），但是有一个奇怪的问题：当我试图在播放器中播放结果视频时，它正在播放，比如18秒，之后它开始于开始！

之后就可以了。

为什么会发生？

videoAsset，audioAsset和audioAsset2只是用URL初始化的AVAssets。

//Creating AVMutableComposition

var mixComposition = AVMutableComposition()

let videoTrack = mixComposition.addMutableTrackWithMediaType(AVMediaTypeVideo, preferredTrackID: Int32(kCMPersistentTrackID_Invalid))
    try! videoTrack.insertTimeRange(CMTimeRangeMake(kCMTimeZero, videoAsset.duration),
            ofTrack: videoAsset.tracksWithMediaType(AVMediaTypeVideo)[0],
            atTime: kCMTimeZero)


let audioTrack = mixComposition.addMutableTrackWithMediaType(AVMediaTypeAudio, preferredTrackID: 0)
        try! audioTrack.insertTimeRange(CMTimeRangeMake(kCMTimeZero, CMTimeAdd(kCMTimeZero, audioAsset.duration)),ofTrack: audioAsset.tracksWithMediaType(AVMediaTypeAudio)[0], atTime: kCMTimeZero)

//the first audiotrack is very short, it's just an overlay for the first several seconds               

let audioTrack2 = mixComposition.addMutableTrackWithMediaType(AVMediaTypeAudio, preferredTrackID: 1)
    try! audioTrack2.insertTimeRange(CMTimeRangeMake(kCMTimeZero, videoAsset.duration), ofTrack: audioAsset2.tracksWithMediaType(AVMediaTypeAudio)[0], atTime: kCMTimeZero)

//this one is the main audiotrack for the video. its length slighly bigger than video duration, so I use videoAsset.duration here

//Player

self.videoitem = AVPlayerItem(asset: mixComposition)

player = AVPlayer(playerItem: self.videoitem)
    let playerLayer = AVPlayerLayer(player: player)
                playerLayer.backgroundColor = UIColor.blackColor().CGColor
    playerLayer.frame = CGRectMake(0, 0, screenWidth, screenHeight)
                self.view.layer.addSublayer(playerLayer)

    NSNotificationCenter.defaultCenter().addObserver(self,
                    selector: "playerItemDidReachEnd:",
                    name: AVPlayerItemDidPlayToEndTimeNotification,
                    object: player.currentItem)

    player.volume = 0.7
    player.play()

AVMutableComposition结果中的重复视频

0 个答案: