我要求从文档目录加载所有视频，然后合并为单个视频。然后将视频上传到服务器上。但是这段代码只合并了两个视频。我如何合并多个视频。
func mergeVideo(index:Int){
print("index:\(index)")
let item:AVPlayerItem!
Utility.showActivityIndicator()
var url = String()
var url2 = String()
url = fileManager.appending(videoFileNames[index] + ".MOV")
url2 = fileManager.appending(videoFileNames[index+1] + ".MOV")
let avAsset = AVAsset(url:NSURL(fileURLWithPath: url) as URL)
let avAsset2 = AVAsset(url:NSURL(fileURLWithPath: url2) as URL)
firstAsset = avAsset
secondAsset = avAsset2
if let firstAsset = firstAsset, let secondAsset = secondAsset {
// 1 - Create AVMutableComposition object. This object will hold your AVMutableCompositionTrack instances.
let mixComposition = AVMutableComposition()
// 2 - Create two video tracks
let firstTrack = mixComposition.addMutableTrack(withMediaType: AVMediaTypeVideo, preferredTrackID: Int32(kCMPersistentTrackID_Invalid))
do {
try firstTrack.insertTimeRange(CMTimeRangeMake(kCMTimeZero, firstAsset.duration), of: firstAsset.tracks(withMediaType: AVMediaTypeVideo)[0], at: kCMTimeZero)
} catch _ {
print("Failed to load first track")
}
let secondTrack = mixComposition.addMutableTrack(withMediaType: AVMediaTypeVideo, preferredTrackID: Int32(kCMPersistentTrackID_Invalid))
do {
try secondTrack.insertTimeRange(CMTimeRangeMake(kCMTimeZero, secondAsset.duration), of: secondAsset.tracks(withMediaType: AVMediaTypeVideo)[0], at: firstAsset.duration)
} catch _ {
print("Failed to load second track")
}
// 2.1
let mainInstruction = AVMutableVideoCompositionInstruction()
mainInstruction.timeRange = CMTimeRangeMake(kCMTimeZero, CMTimeAdd(firstAsset.duration, secondAsset.duration))
// 2.2
let firstInstruction = videoCompositionInstructionForTrack(firstTrack, asset: firstAsset)
firstInstruction.setOpacity(0.0, at: firstAsset.duration)
let secondInstruction = videoCompositionInstructionForTrack(secondTrack, asset: secondAsset)
// 2.3
mainInstruction.layerInstructions = [firstInstruction, secondInstruction]
let mainComposition = AVMutableVideoComposition()
mainComposition.instructions = [mainInstruction]
mainComposition.frameDuration = CMTimeMake(1, 30)
mainComposition.renderSize = CGSize(width: UIScreen.main.bounds.width, height: UIScreen.main.bounds.height)
item = AVPlayerItem(asset: mixComposition)
item.videoComposition = mainComposition
// 3 -Code for Audio track
/*
if let loadedAudioAsset = audioAsset {
let audioTrack = mixComposition.addMutableTrack(withMediaType: AVMediaTypeAudio, preferredTrackID: 0)
do {
try audioTrack.insertTimeRange(CMTimeRangeMake(kCMTimeZero, CMTimeAdd(firstAsset.duration, secondAsset.duration)),
of: loadedAudioAsset.tracks(withMediaType: AVMediaTypeAudio)[0] ,
at: kCMTimeZero)
} catch _ {
print("Failed to load Audio track")
}
}*/
// 4 - Get path
let documentDirectory = NSSearchPathForDirectoriesInDomains(.documentDirectory, .userDomainMask, true)[0]
let dateFormatter = DateFormatter()
dateFormatter.dateStyle = .long
dateFormatter.timeStyle = .short
let date = dateFormatter.string(from: Date())
let savePath = (documentDirectory as NSString).appendingPathComponent("mergeVideo-\(date).mov")
MergeURL = URL(fileURLWithPath: savePath)
// 5 - Create Exporter
guard let exporter = AVAssetExportSession(asset: mixComposition, presetName: AVAssetExportPresetHighestQuality) else { return }
exporter.outputURL = MergeURL
exporter.outputFileType = AVFileTypeQuickTimeMovie
exporter.shouldOptimizeForNetworkUse = true
exporter.videoComposition = mainComposition
// 6 - Perform the Export
exporter.exportAsynchronously() {
DispatchQueue.main.async { _ in
self.exportDidFinish(exporter)
}
}
}
}
func orientationFromTransform(_ transform: CGAffineTransform) -> (orientation: UIImageOrientation, isPortrait: Bool) {
var assetOrientation = UIImageOrientation.up
var isPortrait = false
if transform.a == 0 && transform.b == 1.0 && transform.c == -1.0 && transform.d == 0 {
assetOrientation = .right
isPortrait = true
} else if transform.a == 0 && transform.b == -1.0 && transform.c == 1.0 && transform.d == 0 {
assetOrientation = .left
isPortrait = true
} else if transform.a == 1.0 && transform.b == 0 && transform.c == 0 && transform.d == 1.0 {
assetOrientation = .up
} else if transform.a == -1.0 && transform.b == 0 && transform.c == 0 && transform.d == -1.0 {
assetOrientation = .down
}
return (assetOrientation, isPortrait)
}
func videoCompositionInstructionForTrack(_ track: AVCompositionTrack, asset: AVAsset) -> AVMutableVideoCompositionLayerInstruction {
let instruction = AVMutableVideoCompositionLayerInstruction(assetTrack: track)
let assetTrack = asset.tracks(withMediaType: AVMediaTypeVideo)[0]
let transform = assetTrack.preferredTransform
let assetInfo = orientationFromTransform(transform)
var scaleToFitRatio = UIScreen.main.bounds.width / assetTrack.naturalSize.width
if assetInfo.isPortrait {
scaleToFitRatio = UIScreen.main.bounds.width / assetTrack.naturalSize.height
let scaleFactor = CGAffineTransform(scaleX: scaleToFitRatio, y: scaleToFitRatio)
instruction.setTransform(assetTrack.preferredTransform.concatenating(scaleFactor),
at: kCMTimeZero)
} else {
let scaleFactor = CGAffineTransform(scaleX: scaleToFitRatio, y: scaleToFitRatio)
var concat = assetTrack.preferredTransform.concatenating(scaleFactor).concatenating(CGAffineTransform(translationX: 0, y: UIScreen.main.bounds.width / 2))
if assetInfo.orientation == .down {
let fixUpsideDown = CGAffineTransform(rotationAngle: CGFloat(M_PI))
let windowBounds = UIScreen.main.bounds
let yFix = assetTrack.naturalSize.height + windowBounds.height
let centerFix = CGAffineTransform(translationX: assetTrack.naturalSize.width, y: yFix)
concat = fixUpsideDown.concatenating(centerFix).concatenating(scaleFactor)
}
instruction.setTransform(concat, at: kCMTimeZero)
}
return instruction
}