将视频合并在一起（AVFoundation）

Posted 2023-03-07

【中文标题】将视频合并在一起（AVFoundation）

【英文标题】：merging videos together (AVFoundation)

【发布时间】：2013-08-30 19:29:12

【问题描述】：

在我的应用程序中，我正在录制小视频并将它们添加到 NSMutableArray 中作为 AVAsset 以便我记录已捕获的内容。当用户按下按钮合并它们时，最终结果只是拍摄的第一个视频（例如，如果拍摄了三个短视频，合并后的最终结果只有第一个视频，其他视频不出现）。我在 NSMutableArray 中迭代并将视频拼接在一起的代码在这里：

if (self.capturedVideos.count != 0)         
    //Create AVMutableComposition Object.This object will hold our multiple AVMutableCompositionTrack.
    AVMutableComposition* mixComposition = [[AVMutableComposition alloc] init];

    for (AVAsset *asset in self.capturedVideos) 
        //check if the video is the first one captures so that it  is placed at time 0.
        if ([self.capturedVideos indexOfObject:asset] == 0) 
            AVMutableCompositionTrack *firstTrack = [mixComposition addMutableTrackWithMediaType:AVMediaTypeVideo preferredTrackID:kCMPersistentTrackID_Invalid];
            [firstTrack insertTimeRange:CMTimeRangeMake(kCMTimeZero, asset.duration) ofTrack:[[asset tracksWithMediaType:AVMediaTypeVideo] objectAtIndex:0] atTime:kCMTimeZero error:nil];
            previousAsset = asset;
         else
            AVMutableCompositionTrack *track = [mixComposition addMutableTrackWithMediaType:AVMediaTypeVideo preferredTrackID:kCMPersistentTrackID_Invalid];
            [track insertTimeRange:CMTimeRangeMake(kCMTimeZero, asset.duration) ofTrack:[[asset tracksWithMediaType:AVMediaTypeVideo] objectAtIndex:0] atTime:previousAsset.duration error:nil];
            previousAsset = asset;
        
    

    NSArray *paths = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES);
    NSString *documentsDirectory = [paths objectAtIndex:0];
    NSString *myPathDocs =  [documentsDirectory stringByAppendingPathComponent:
    [NSString stringWithFormat:@"mergeVideo-%d.mov",arc4random() % 1000]];
    NSURL *url = [NSURL fileURLWithPath:myPathDocs];
    // 5 - Create exporter
    AVAssetExportSession *exporter = [[AVAssetExportSession alloc] initWithAsset:mixComposition presetName:AVAssetExportPresetHighestQuality];
    exporter.outputURL=url;
    exporter.outputFileType = AVFileTypeQuickTimeMovie;
    exporter.shouldOptimizeForNetworkUse = YES;
    [exporter exportAsynchronouslyWithCompletionHandler:^
        dispatch_async(dispatch_get_main_queue(), ^
            [self exportDidFinish:exporter];
        );
    ];

for 循环之后的内容用于导出要保存在相机胶卷中的视频。那么我的错误在哪里？持续时间是正确的（所以没有重叠）。但是，我在怀疑某事。我在大括号中的@implementation 之后添加了一个实例变量，它是previousAsset，它跟踪添加的上一个资产，从而知道将下一个放置在哪里。它属于 AVAsset 类，所以我没有初始化它，因为当我尝试它时它向我显示错误。

previousAsset = [[AVAsset alloc] init];

【问题讨论】：

试试这个：- ***.com/questions/37210154/…

【参考方案1】：

斯威夫特版本

func merge(arrayVideos:[AVAsset], completion:@escaping (_ exporter: AVAssetExportSession) -> ()) -> Void 

  let mainComposition = AVMutableComposition()
  let compositionVideoTrack = mainComposition.addMutableTrack(withMediaType: .video, preferredTrackID: kCMPersistentTrackID_Invalid)
  compositionVideoTrack?.preferredTransform = CGAffineTransform(rotationAngle: .pi / 2)

  let soundtrackTrack = mainComposition.addMutableTrack(withMediaType: .audio, preferredTrackID: kCMPersistentTrackID_Invalid)

  var insertTime = kCMTimeZero

  for videoAsset in arrayVideos 
    try! compositionVideoTrack?.insertTimeRange(CMTimeRangeMake(kCMTimeZero, videoAsset.duration), of: videoAsset.tracks(withMediaType: .video)[0], at: insertTime)
    try! soundtrackTrack?.insertTimeRange(CMTimeRangeMake(kCMTimeZero, videoAsset.duration), of: videoAsset.tracks(withMediaType: .audio)[0], at: insertTime)

    insertTime = CMTimeAdd(insertTime, videoAsset.duration)
  

  let outputFileURL = URL(fileURLWithPath: NSTemporaryDirectory() + "merge.mp4")

  let fileManager = FileManager()
  fileManager.removeItemIfExisted(outputFileURL)

  let exporter = AVAssetExportSession(asset: mainComposition, presetName: AVAssetExportPresetHighestQuality)

  exporter?.outputURL = outputFileURL
  exporter?.outputFileType = AVFileType.mp4
  exporter?.shouldOptimizeForNetworkUse = true

  exporter?.exportAsynchronously 
    DispatchQueue.main.async 
      completion(exporter!)
    
  

【讨论】：

如何访问合并后的视频？

视频应该在 exporter.outputURL 上可用

【参考方案2】：

这样就可以了

      AVMutableComposition *mainComposition = [[AVMutableComposition alloc] init];
      AVMutableCompositionTrack *compositionVideoTrack = [mainComposition addMutableTrackWithMediaType:AVMediaTypeVideo preferredTrackID:kCMPersistentTrackID_Invalid];


      AVMutableCompositionTrack *soundtrackTrack = [mainComposition addMutableTrackWithMediaType:AVMediaTypeAudio preferredTrackID:kCMPersistentTrackID_Invalid];
      CMTime insertTime = kCMTimeZero;

      for (AVAsset *videoAsset in assets) 

          [compositionVideoTrack insertTimeRange:CMTimeRangeMake(kCMTimeZero, videoAsset.duration) ofTrack:[[videoAsset tracksWithMediaType:AVMediaTypeVideo] objectAtIndex:0] atTime:insertTime error:nil];

          [soundtrackTrack insertTimeRange:CMTimeRangeMake(kCMTimeZero, videoAsset.duration) ofTrack:[[videoAsset tracksWithMediaType:AVMediaTypeAudio] objectAtIndex:0] atTime:insertTime error:nil];

          // Updating the insertTime for the next insert
          insertTime = CMTimeAdd(insertTime, videoAsset.duration);
      

      NSArray *paths = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES);
      NSString *documentsDirectory = [paths objectAtIndex:0];

      // Creating a full path and URL to the exported video
      NSString *outputVideoPath =  [documentsDirectory stringByAppendingPathComponent:
                              [NSString stringWithFormat:@"mergeVideo-%d.mov",arc4random() % 1000]];

      // NSString *documentsDirectory = [paths objectAtIndex:0];
      NSString *myPathDocs =  [documentsDirectory stringByAppendingPathComponent:
                         current_name];
      NSURL *outptVideoUrl = [NSURL fileURLWithPath:myPathDocs];
      AVAssetExportSession *exporter = [[AVAssetExportSession alloc] initWithAsset:mainComposition presetName:AVAssetExportPreset640x480];

      // Setting attributes of the exporter
      exporter.outputURL=outptVideoUrl;
      exporter.outputFileType =AVFileTypeMPEG4;   //AVFileTypeQuickTimeMovie;
      exporter.shouldOptimizeForNetworkUse = YES;
      [exporter exportAsynchronouslyWithCompletionHandler:^
          dispatch_async(dispatch_get_main_queue(), ^
              //completion(exporter);
              [self exportDidFinish:exporter];
              // [self exportDidFinish:exporter:assets];
          );
      ];

这会很好..

【参考方案3】：

更新了@brenoxp 对 Swift 5.1 的回答

func merge(arrayVideos:[AVAsset], completion:@escaping (URL?, Error?) -> ()) 

  let mainComposition = AVMutableComposition()
  let compositionVideoTrack = mainComposition.addMutableTrack(withMediaType: .video, preferredTrackID: kCMPersistentTrackID_Invalid)
  compositionVideoTrack?.preferredTransform = CGAffineTransform(rotationAngle: .pi / 2)

  let soundtrackTrack = mainComposition.addMutableTrack(withMediaType: .audio, preferredTrackID: kCMPersistentTrackID_Invalid)

    var insertTime = CMTime.zero

  for videoAsset in arrayVideos 
    try! compositionVideoTrack?.insertTimeRange(CMTimeRangeMake(start: .zero, duration: videoAsset.duration), of: videoAsset.tracks(withMediaType: .video)[0], at: insertTime)
    try! soundtrackTrack?.insertTimeRange(CMTimeRangeMake(start: .zero, duration: videoAsset.duration), of: videoAsset.tracks(withMediaType: .audio)[0], at: insertTime)

    insertTime = CMTimeAdd(insertTime, videoAsset.duration)
  

  let outputFileURL = URL(fileURLWithPath: NSTemporaryDirectory() + "merge.mp4")

  let fileManager = FileManager()
  try? fileManager.removeItem(at: outputFileURL)

  let exporter = AVAssetExportSession(asset: mainComposition, presetName: AVAssetExportPresetHighestQuality)

  exporter?.outputURL = outputFileURL
  exporter?.outputFileType = AVFileType.mp4
  exporter?.shouldOptimizeForNetworkUse = true

  exporter?.exportAsynchronously 
    if let url = exporter?.outputURL
        completion(url, nil)
    
    if let error = exporter?.error 
        completion(nil, error)
    
  

【参考方案4】：

Git Hub 上有一个很棒的示例项目，它是一个很好的起点，可以帮助您在应用程序中以更可重用的方式做到这一点

https://github.com/khoavd-dev/MergeVideos/blob/master/MergeVideos/VideoManager/KVVideoManager.swift