假设我们有两个视频资源（AVAsset对象），我们称之为空白和主要，其中主是随机视频限制长度，比方说2-5分钟，空白始终为4秒视频，我们希望按以下顺序合并视频：
空白 - 主要 - 空白
// 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)")
}
}
}
假设原始录像机在720p质量下持续5分钟占用大约200MB的空间，在主视频的开始和结束时添加4s空白视频不应该大幅改变大小，并且应该非常快速地完成处理。
然而，结果是视频的大小是原始视频的2到2.5倍（所以400 - 500 MB）并且处理时间太长。
请指教，
由于
答案 0 :(得分：1)
在这里，我准备了一个自定义课程，您可以在其中传递视频名称，并将这些视频保存到捆绑包中。运行应用程序后，它将根据您的要求生成新的视频文件，并将其放入应用程序文档目录路径中。
使用Swift 4我准备了这个演示
//
// ViewController.swift
// SOVideoMergingDemo
//
// Created by iOS Test User on 03/01/18.
// Copyright © 2018 Test User. Ltd. All rights reserved.
//
import UIKit
import AVFoundation
import MediaPlayer
import Photos
import AssetsLibrary
import AVKit
class ViewController : UIViewController {
//--------------------------------------------------
//MARK:
//MARK: - IBOutlets
//--------------------------------------------------
//--------------------------------------------------
//MARK:
//MARK: - Properties
//--------------------------------------------------
var videoUrls : [URL] = []
var arrVideoAsset : [AVAsset] = []
let video1 = "1"
let video2 = "2"
let outPutVideo = "MergedVideo.mp4"
let semaphore = DispatchSemaphore(value: 1)
//--------------------------------------------------
//MARK:
//MARK: - Custom Methods
//--------------------------------------------------
func getVideoURL(forVideo : String) -> URL {
let videoPath = Bundle.main.path(forResource: forVideo, ofType:"mp4")
let vidURL = URL(fileURLWithPath: videoPath!)
return vidURL
}
//--------------------------------------------------
func mergeVideos(arrVideoAsset : [AVAsset]) {
let mixComposition = AVMutableComposition()
//Tracks to insert in Composition for Merging
// Create video tracks
let firstTrack = mixComposition.addMutableTrack(withMediaType: .video, preferredTrackID: kCMPersistentTrackID_Invalid)
let secondTrack = mixComposition.addMutableTrack(withMediaType: .video, preferredTrackID: kCMPersistentTrackID_Invalid)
let thirdTrack = mixComposition.addMutableTrack(withMediaType: .video, preferredTrackID: kCMPersistentTrackID_Invalid)
do {
try firstTrack?.insertTimeRange(CMTimeRangeMake(kCMTimeZero, arrVideoAsset[0].duration), of: arrVideoAsset[0].tracks(withMediaType: .video)[0], at: kCMTimeZero)
} catch _ {
print("Failed to load first track")
}
do {
try secondTrack?.insertTimeRange(CMTimeRangeMake(kCMTimeZero, arrVideoAsset[1].duration), of: arrVideoAsset[1].tracks(withMediaType: .video)[0], at: arrVideoAsset[0].duration)
} catch _ {
print("Failed to load second track")
}
do {
try thirdTrack?.insertTimeRange(CMTimeRangeMake(kCMTimeZero, arrVideoAsset[0].duration), of: arrVideoAsset[0].tracks(withMediaType: .video)[0], at: arrVideoAsset[1].duration)
} catch _ {
print("Failed to load second track")
}
//This Instruciton is Created for Merging Video Tracks
let compositionInstruction = AVMutableVideoCompositionInstruction()
compositionInstruction.timeRange = CMTimeRangeMake(kCMTimeZero,CMTimeAdd(arrVideoAsset[0].duration, CMTimeAdd(arrVideoAsset[1].duration, arrVideoAsset[2].duration)))
//Creating Layer Instruction for Videos
let firstInstruction = videoCompositionInstructionForTrack(firstTrack!, asset: arrVideoAsset[0])
firstInstruction.setOpacity(0.0, at: arrVideoAsset[0].duration )
let secondInstruction = videoCompositionInstructionForTrack(secondTrack!, asset: arrVideoAsset[1])
secondInstruction.setOpacity(0.0, at: arrVideoAsset[1].duration)
let thirdInstruction = videoCompositionInstructionForTrack(thirdTrack!, asset: arrVideoAsset[2])
compositionInstruction.layerInstructions = [firstInstruction, secondInstruction,thirdInstruction]
//By Changing These Height and Width User can affect Size of Merged Video. Calucalte it Carefully and As per you needs
let height = (Float((firstTrack?.naturalSize.height)!) < Float((secondTrack?.naturalSize.height)!)) ? firstTrack?.naturalSize.height : secondTrack?.naturalSize.height
let width = (Float((firstTrack?.naturalSize.width)!) < Float((secondTrack?.naturalSize.width)!)) ? firstTrack?.naturalSize.width : secondTrack?.naturalSize.width
let mainComposition = AVMutableVideoComposition()
mainComposition.instructions = [compositionInstruction]
mainComposition.frameDuration = CMTimeMake(1, 30)
mainComposition.renderSize = CGSize(width:width!,height: height!)
let exporter = AVAssetExportSession(asset:mixComposition, presetName: AVAssetExportPresetHighestQuality)
exporter?.outputURL = URL(fileURLWithPath: getDocumentDirectoryPath() + "/" + outPutVideo)
exporter?.outputFileType = AVFileType.mp4
exporter?.shouldOptimizeForNetworkUse = true
exporter?.videoComposition = mainComposition
print(self.getDocumentDirectoryPath())
exporter?.exportAsynchronously(completionHandler: {
DispatchQueue.main.async {
if exporter?.status == AVAssetExportSessionStatus.completed {
do {
let videoData = try Data(contentsOf: exporter!.outputURL!)
try videoData.write(to: URL(fileURLWithPath : self.getDocumentDirectoryPath() + "/" + self.outPutVideo), options: Data.WritingOptions.atomic)
} catch {
print("Failed to Save video ===>>> \(error.localizedDescription)")
}
//Uncomment This If you want to save video in Photos Library
// PHPhotoLibrary.shared().performChanges({
// PHAssetChangeRequest.creationRequestForAssetFromVideo(atFileURL: (exporter?.outputURL)!)
// }, completionHandler: { (success, error) in
// if success {
// let fetchOptions = PHFetchOptions()
// fetchOptions.sortDescriptors = [NSSortDescriptor.init(key:"creationDate", ascending: false)]
// _ = PHAsset.fetchAssets(with: .video, options:fetchOptions).firstObject
// } else {
// print("Error in Saving File in Photo Libaray -> \(String(describing: error?.localizedDescription))")
// }
// })
} else {
print("Error -> \(String(describing: exporter?.error?.localizedDescription))")
}
}
})
}
//--------------------------------------------------
//This Methiod is Used to Make Layer Instruction for Particular Video
func videoCompositionInstructionForTrack(_ track: AVCompositionTrack, asset: AVAsset) -> AVMutableVideoCompositionLayerInstruction {
let instruction = AVMutableVideoCompositionLayerInstruction(assetTrack: track)
let assetTrack = asset.tracks(withMediaType: AVMediaType.video)[0]
let scale : CGAffineTransform = CGAffineTransform(scaleX: 1, y:1)
instruction.setTransform(assetTrack.preferredTransform.concatenating(scale), at: kCMTimeZero)
return instruction
}
//--------------------------------------------------
func getDocumentDirectoryPath() -> String {
let arrPaths = NSSearchPathForDirectoriesInDomains(.documentDirectory, .userDomainMask, true)
return arrPaths[0]
}
//--------------------------------------------------
//MARK:
//MARK: - View Life Cycle Methods
//--------------------------------------------------
override func viewDidLoad() {
super.viewDidLoad()
// Do any additional setup after loading the view.
//Prepare Video Assets
arrVideoAsset.append(AVAsset(url:getVideoURL(forVideo:video1)))
arrVideoAsset.append(AVAsset(url:getVideoURL(forVideo:video2)))
arrVideoAsset.append(AVAsset(url:getVideoURL(forVideo:video1)))
//Merge this Videos
mergeVideos(arrVideoAsset:arrVideoAsset)
}
}