Question

我正在合并多个视频（植入暂停按钮），并且当将来自后置摄像头的视频与来自前置摄像头的视频合并时，一切工作正常，然后其中一个视频在新视频中被颠倒过来（合并视频）。我的代码：

let mixComposition = AVMutableComposition() 

let videoTrack = mixComposition.addMutableTrackWithMediaType(AVMediaTypeVideo, preferredTrackID: CMPersistentTrackID())
let trackAudio = mixComposition.addMutableTrackWithMediaType(AVMediaTypeAudio, preferredTrackID: CMPersistentTrackID())

var insertTime = kCMTimeZero
for var i = 0; i < currentAssets.count; i++ {
    let tracks = currentAssets[i].tracksWithMediaType(AVMediaTypeVideo)
    let audios = currentAssets[i].tracksWithMediaType(AVMediaTypeAudio)

    let assetTrack:AVAssetTrack = tracks[0] as AVAssetTrack
    try videoTrack.insertTimeRange(CMTimeRangeMake(kCMTimeZero, currentAssets[i].duration), ofTrack: assetTrack, atTime: insertTime)
    let assetTrackAudio:AVAssetTrack = audios[0] as AVAssetTrack
    try trackAudio.insertTimeRange(CMTimeRangeMake(kCMTimeZero, currentAssets[i].duration), ofTrack: assetTrackAudio, atTime: insertTime)
    insertTime = CMTimeAdd(insertTime, currentAssets[i].duration)
}
videoTrack.preferredTransform = assetTrack.preferredTransform

let documentsURL = NSFileManager.defaultManager().URLsForDirectory(.DocumentDirectory,inDomains: .UserDomainMask).last!
let mediaURL = documentsURL.URLByAppendingPathComponent(AppMediaFolder)
let savePath = mediaURL.URLByAppendingPathComponent("\(NSUUID().UUIDString).mp4").path!

self.createDirectoryIfExists(mediaURL)
let url = NSURL(fileURLWithPath: savePath)

currentAssets.removeAll()
currentAssets.append(AVAsset(URL: url))

//Create Exporter
let exporter = AVAssetExportSession(asset: mixComposition, presetName: AVAssetExportPresetHighestQuality)!
exporter.outputURL = url
exporter.outputFileType = AVFileTypeMPEG4
exporter.shouldOptimizeForNetworkUse = true

Answer 1

您需要注意renderSize的{{1}}和AVMutableVideoComposition的转换。

要正确对齐它们，您需要以正确的度数翻译和旋转视频。要将其翻转过来，您需要将其旋转180度并将其转换为正确的坐标：

AVMutableVideoCompositionLayerInstruction

在我的情况下，... videoComposition.renderSize = CGSizeMake(X, Y) ... let translate = CGAffineTransformMakeTranslation(X, Y); let rotate = CGAffineTransformRotate(translate, CGFloat(ANGLE_IN_RADIANS)) ...和平移设置为1280和720，180度旋转基本上是renderSize弧度：

M_PI

最后，您仍然需要将此 videoComposition 添加到let videoComposition = AVMutableVideoComposition() videoComposition.renderSize = CGSizeMake(1280, 720) videoComposition.frameDuration = CMTimeMake(1, 30) let videoInstruction = AVMutableVideoCompositionInstruction() instruction.timeRange = CMTimeRangeMake(kCMTimeZero, CMTimeMakeWithSeconds(180, 30)) let transformInstruction:AVMutableVideoCompositionLayerInstruction = AVMutableVideoCompositionLayerInstruction(assetTrack: clipVideoTrack) let translate = CGAffineTransformMakeTranslation(1280, 720); let rotate = CGAffineTransformRotate(translate, CGFloat(M_PI)) transformInstruction.setTransform(rotate, atTime: kCMTimeZero) videoInstruction.layerInstructions = [transformInstruction] videoComposition.instructions = [videoInstruction]，才能使转换生效。

如何通过合并前后摄像头的视频来解决我的方向问题

1 个答案: