Question

我有一个[AVAsset]数组，我试图将所有这些资产组合成一个资产，以便我可以无缝播放视频（我尝试使用AVQueuePlayer，但这不会播放资产无缝地）。

以下是我到目前为止的情况，但是当我尝试播放最终合成时，它只播放第一首曲目，即使它显示它包含所有曲目且总持续时间等于所有曲目。

我是否错过了一个步骤，即使看起来所有曲目都在合成中？如果AVPlayerItem有多个轨道，我可能需要以不同的方式处理AVPlayer吗？

let playerLayer: AVPlayerLayer = AVPlayerLayer()
lazy var videoPlayer: AVPlayer = AVPlayer()

var videoClips = [AVAsset]()

let videoComposition = AVMutableComposition()
var playerItem: AVPlayerItem!
var lastTime: CMTime = kCMTimeZero

for clipIndex in videoClips {

    let videoCompositionTrack = videoComposition.addMutableTrackWithMediaType(AVMediaTypeVideo, preferredTrackID: Int32(kCMPersistentTrackID_Invalid))

    do {
        try videoCompositionTrack.insertTimeRange(CMTimeRangeMake(kCMTimeZero, clipIndex.duration),
                                                  ofTrack: clipIndex.tracksWithMediaType(AVMediaTypeVideo)[0] ,
                                                  atTime: lastTime)
        lastTime = CMTimeAdd(lastTime, clipIndex.duration)
    } catch {
        print("Failed to insert track")
    }
}
print("VideoComposition Tracks: \(videoComposition.tracks.count)") // Shows multiple tracks

playerItem = AVPlayerItem(asset: videoComposition)
print("PlayerItem Duration: \(playerItem.duration.seconds)") // Shows the duration of all tracks together
print("PlayerItem Tracks: \(playerItem.tracks.count)") // Shows same number of tracks as the VideoComposition Track count

videoPlayer = AVPlayer(playerItem: playerItem)
playerLayer.player = videoPlayer
videoPlayer.volume = 0.0
videoPlayer.play()  // Only plays the first track

Answer 1

我能够找到答案最重要的问题。为了将所有剪辑一起播放，它们需要在同一轨道中。为此，请将以下行移到for循环之外（之前）：

let playerLayer: AVPlayerLayer = AVPlayerLayer()
lazy var videoPlayer: AVPlayer = AVPlayer()

var videoClips = [AVAsset]()

let videoComposition = AVMutableComposition()
var playerItem: AVPlayerItem!
var lastTime: CMTime = kCMTimeZero

let videoCompositionTrack = videoComposition.addMutableTrackWithMediaType(AVMediaTypeVideo, preferredTrackID: Int32(kCMPersistentTrackID_Invalid))

for clipIndex in videoClips {

    do {
        try videoCompositionTrack.insertTimeRange(CMTimeRangeMake(kCMTimeZero, clipIndex.duration),
                                                  ofTrack: clipIndex.tracksWithMediaType(AVMediaTypeVideo)[0] ,
                                                  atTime: lastTime)
        lastTime = CMTimeAdd(lastTime, clipIndex.duration)
    } catch {
        print("Failed to insert track")
    }
}
print("VideoComposition Tracks: \(videoComposition.tracks.count)") // Shows multiple tracks

playerItem = AVPlayerItem(asset: videoComposition)
print("PlayerItem Duration: \(playerItem.duration.seconds)") // Shows the duration of all tracks together
print("PlayerItem Tracks: \(playerItem.tracks.count)") // Shows same number of tracks as the VideoComposition Track count

videoPlayer = AVPlayer(playerItem: playerItem)
playerLayer.player = videoPlayer
videoPlayer.volume = 0.0
videoPlayer.play()  // Does play all clips sequentially

以下是完整的更正代码：

using (DefaultSoapClient soapClient = new DefaultSoapClient())
                    {
                        InitializeWebService(soapClient,sAUser,sAPass,vCompany,vBranchID);

                        Shipment shipmentToBeFound = new Shipment
                        {
                            Type = new StringSearch { Value = shipmentType },
                            ShipmentNbr = new StringSearch { Value = shipmentNbr },
                        };
                        Shipment shipment = (Shipment)soapClient.Get(shipmentToBeFound);

                        int iLineNbr =  Int32.Parse(sLineNbr);
                        ShipmentDetail shipmentLine = shipment.Details.Single(
                            orderLineToBeUpdated =>                                
                            orderLineToBeUpdated.LineNbr.Value == iLineNbr);
                            shipmentLine.LocationID = new StringValue { Value = vLocation.Trim() };
                            shipmentLine.ShippedQty = new DecimalValue { Value = decimal.Parse(sOrderedQty) };

                            shipment = (Shipment)soapClient.Put(shipment);

                        soapClient.Logout();

                    }

编辑：我之前提到，我仍然想知道如何在一个资产中播放多个曲目。这不是它的工作方式，我现在明白了。一个很好的资源：

https://developer.apple.com/library/mac/documentation/AudioVideo/Conceptual/AVFoundationPG/Articles/04_MediaCapture.html

AVMutableComposition - 仅播放第一曲目（Swift）

1 个答案: