Предположим, что у нас есть два видеоатрибута (объекты AVAsset), позвоните им blank и main, где main - это видео случайных ограниченная длина, допустим, 2-5 минут, а blank - это 4-секундное видео, мы хотим объединить видео в следующем порядке:
blank - main - blank
// Create AVMutableComposition Object.This object will hold our multiple AVMutableCompositionTrack.
let mixComposition = AVMutableComposition()
let assets = [blank, main, blank]
var totalTime : CMTime = CMTimeMake(0, 0)
var atTimeM: CMTime = CMTimeMake(0, 0)
Utils.log([blank.duration, main.duration])
// VIDEO TRACK
let videoTrack = mixComposition.addMutableTrack(withMediaType: AVMediaTypeVideo, preferredTrackID: Int32(kCMPersistentTrackID_Invalid))
for (index,asset) in assets.enumerated() {
do {
if index == 0 {
atTimeM = kCMTimeZero
} else {
atTimeM = totalTime // <-- Use the total time for all the videos seen so far.
}
try videoTrack.insertTimeRange(CMTimeRangeMake(kCMTimeZero, asset.duration), of: asset.tracks(withMediaType: AVMediaTypeVideo)[0], at: atTimeM)
} catch let error as NSError {
Utils.log("error: \(error)")
}
totalTime = CMTimeAdd(totalTime, asset.duration)
}
// AUDIO TRACK
let audioTrack = mixComposition.addMutableTrack(withMediaType: AVMediaTypeAudio, preferredTrackID: kCMPersistentTrackID_Invalid)
do {
try audioTrack.insertTimeRange(CMTimeRangeMake(kCMTimeZero, main.duration), of: main.tracks(withMediaType: AVMediaTypeAudio)[0], at: blank.duration)
} catch _ {
completionHandler(nil, ErrorType(rawValue: "Unable to add audio in composition."))
return
}
let outputURL = mainVideoObject.getDirectoryURL()?.appendingPathComponent("video-with-blank.mp4")
guard let exporter = AVAssetExportSession(asset: mixComposition, presetName: AVAssetExportPreset1280x720) else {
completionHandler(nil, ErrorType(rawValue: "Unable to create export session."))
return
}
let mainInstruction = AVMutableVideoCompositionInstruction()
mainInstruction.timeRange = CMTimeRangeMake(kCMTimeZero, CMTimeAdd(blank.duration, CMTimeAdd(main.duration, blank.duration)))
// Fixing orientation
let firstLayerInstruction = AVMutableVideoCompositionLayerInstruction(assetTrack: videoTrack)
let firstAssetTrack = blank.tracks(withMediaType: AVMediaTypeVideo)[0]
firstLayerInstruction.setTransform(firstAssetTrack.preferredTransform, at: kCMTimeZero)
firstLayerInstruction.setOpacity(0.0, at: blank.duration)
let secondLayerInstruction = AVMutableVideoCompositionLayerInstruction(assetTrack: videoTrack)
let secondAssetTrack = main.tracks(withMediaType: AVMediaTypeVideo)[0]
var isSecondAssetPortrait = false
let secondTransform = secondAssetTrack.preferredTransform
if (secondTransform.a == 0 && secondTransform.b == 1.0 && secondTransform.c == -1.0 && secondTransform.d == 0) {
isSecondAssetPortrait = true
}
if (secondTransform.a == 0 && secondTransform.b == -1.0 && secondTransform.c == 1.0 && secondTransform.d == 0) {
isSecondAssetPortrait = true
}
secondLayerInstruction.setTransform(secondAssetTrack.preferredTransform, at: blank.duration)
secondLayerInstruction.setOpacity(0.0, at: CMTimeAdd(blank.duration, main.duration))
let thirdLayerInstruction = AVMutableVideoCompositionLayerInstruction(assetTrack: videoTrack)
let thirdAssetTrack = blank.tracks(withMediaType: AVMediaTypeVideo)[0]
thirdLayerInstruction.setTransform(thirdAssetTrack.preferredTransform, at: CMTimeAdd(blank.duration, main.duration))
mainInstruction.layerInstructions = [firstLayerInstruction, secondLayerInstruction, thirdLayerInstruction]
var naturalSize = CGSize()
if(isSecondAssetPortrait) {
naturalSize = CGSize(width: secondAssetTrack.naturalSize.height, height: secondAssetTrack.naturalSize.width)
} else {
naturalSize = secondAssetTrack.naturalSize
}
let renderWidth = naturalSize.width
let renderHeight = naturalSize.height
let mainCompositionInst = AVMutableVideoComposition()
mainCompositionInst.instructions = [mainInstruction]
mainCompositionInst.frameDuration = CMTimeMake(1, 30)
mainCompositionInst.renderSize = CGSize(width: renderWidth, height: renderHeight)
exporter.outputURL = outputURL
exporter.outputFileType = AVFileTypeMPEG4
exporter.videoComposition = mainCompositionInst
//exporter.shouldOptimizeForNetworkUse = true
exporter.exportAsynchronously {
if exporter.status == .completed {
completionHandler(AVAsset(url: outputURL!), nil)
} else {
completionHandler(nil, ErrorType(rawValue: "Unable to export video."))
if let error = exporter.error {
Utils.log("Unable to export video. \(error)")
}
}
}
Предполагая, что оригинальный видеомагнитофон в течение 5 минут с качеством 720p занимает около 200 МБ пространства, добавление 4-го пустого видео при начале и конце основного видео не должно радикально изменять размер и должно заканчиваться очень быстро.
Однако результат - это видеоролик размером от 2 до 2,5x от размера исходного видео (так 400 - 500 МБ) и занимает слишком много времени для обработки.
Просьба сообщить,
Спасибо