无法使用 AVAssetExportSession 导出 AVMutableComposition答案

【问题标题】：Can not export AVMutableComposition with AVAssetExportSession无法使用 AVAssetExportSession 导出 AVMutableComposition
【发布时间】：2018-07-23 13:46:35
【问题描述】：

这是作曲创作的一部分：

  AVMutableComposition* mixComposition = [[AVMutableComposition alloc] init];

  for (NSDictionary *track in tracks) {
    NSURL *url = [[NSURL alloc] initWithString:track[@"url"]];
    AVURLAsset *urlAsset = [AVURLAsset URLAssetWithURL:url options:nil];
    AVMutableCompositionTrack *firstTrack = [mixComposition addMutableTrackWithMediaType:AVMediaTypeAudio
                                                                        preferredTrackID:kCMPersistentTrackID_Invalid];

    [firstTrack insertTimeRange:CMTimeRangeMake(kCMTimeZero, urlAsset.duration)
                        ofTrack:[[urlAsset tracksWithMediaType:AVMediaTypeAudio] objectAtIndex:0]
                         atTime:kCMTimeZero
                          error:nil];
  }
  [self persist:mixComposition for:songId];

然后我希望将集合保存在目录中，这样我就不必每次都下载它

合成的输出如下所示：

"AVMutableCompositionTrack: 0x1c4a276a0 trackID = 1, mediaType = soun, editCount = 1", "AVMutableCompositionTrack: 0x1c4a28560 trackID = 2, mediaType = soun, editCount = 1"...,

- (void)persist:(AVMutableComposition *) composition
            for:(NSString *) songId {

  NSLog(@"%@", composition);


  AVAssetExportSession *exportSession = [[AVAssetExportSession alloc]
                                         initWithAsset:composition
                                         presetName:AVAssetExportPresetAppleM4A];
  NSString *path = [NSHomeDirectory() stringByAppendingPathComponent: songId];
  NSURL *url = [NSURL fileURLWithPath: path];
  exportSession.outputURL = url;
  exportSession.shouldOptimizeForNetworkUse = YES;
  exportSession.outputFileType = AVFileTypeAppleM4A;


  //   perform the export
  [exportSession exportAsynchronouslyWithCompletionHandler:^{

    if (AVAssetExportSessionStatusCompleted == exportSession.status) {
      NSLog(@"AVAssetExportSessionStatusCompleted");
      NSLog(@"Path : %@", url);
    } else if (AVAssetExportSessionStatusFailed == exportSession.status) {
      // a failure may happen because of an event out of your control
      // for example, an interruption like a phone call comming in
      // make sure and handle this case appropriately
      NSLog(@"%@", exportSession.error);

    } else {
      NSLog(@"Export Session Status: %ld", (long)exportSession.status);
    }
  }];

}

我得到的错误：

Error Domain=AVFoundationErrorDomain Code=-11800 "该操作可能未完成” UserInfo={NSLocalizedFailureReason=未知错误发生 (-12780), NSLocalizedDescription=操作不能完成，NSUnderlyingError=0x1c0a409f0 {错误 Domain=NSOSStatusErrorDomain Code=-12780 "(null)"}}

【问题讨论】：

标签： objective-c avassetexportsession

【解决方案1】：

您使用的路径必须是您需要导出的文件的内容类型，如下所示：

    let directory = FileManager.default.urls(for: .documentDirectory, in: .userDomainMask).first
    let audioTypeOutput = ".m4a"//type of your file, mp3, m4a for audio
    let exportPath = directory?.appendingPathComponent(name + audioTypeOutput)

希望对您有所帮助！

【讨论】：