Question

我将两个录音（使用AVAudioRecorder录制）合并到一个文件中。使用AVAssetExportSession导出组合文件第一次完美运行（即只要我在当前视图控制器中）但是当再次加载此视图（新会话）时，AVAssetExportSession exportAsynchronouslyWithCompletionHandler：方法根本不会被调用（没有回调！）没有错误没有什么...... 我试图记录AVAssetExportSession对象，我第一次得到这个

<AVAssetExportSession: 0x155b3250, asset = <AVMutableComposition: 0x156474c0 tracks = ("<AVMutableCompositionTrack: 0x156a0bb0 trackID = 1, mediaType = soun, editCount = 0>")>, presetName = AVAssetExportPresetAppleM4A, outputFileType = (null)

这是第二次

<AVAssetExportSession: 0x1559e840, asset = <AVMutableComposition: 0x155f7f30 tracks = ("<AVMutableCompositionTrack: 0x155f0120 trackID = 1, mediaType = soun, editCount = 1>")>, presetName = AVAssetExportPresetAppleM4A, outputFileType = (null)

我注意到的唯一区别是editCount = 1件事。

我知道这听起来令人困惑，这对我来说。无论发生在什么地方？

我的代码：

AVAssetExportSession* exportSession = [AVAssetExportSession
                                       exportSessionWithAsset:composition
                                       presetName:AVAssetExportPresetAppleM4A];

NSLog(@"exportSession: %@", exportSession);


exportSession.outputURL = [NSURL fileURLWithPath:combined];
exportSession.outputFileType = AVFileTypeAppleM4A;
exportSession.shouldOptimizeForNetworkUse = YES;
[exportSession exportAsynchronouslyWithCompletionHandler:^{
    switch (exportSession.status) {
        case AVAssetExportSessionStatusFailed:
            NSLog(@"AVAssetExportSessionStatusFailed");
            break;
        case AVAssetExportSessionStatusCompleted:
            NSLog(@"AVAssetExportSessionStatusCompleted");
            break;
        case AVAssetExportSessionStatusWaiting:
            NSLog(@"AVAssetExportSessionStatusWaiting");
            break;
        default:
            break;
    }

    dispatch_async(dispatch_get_main_queue(), ^{
        [self exportDidFinish:exportSession];
    });

}];

Answer 1

它可能相关也可能不相关，但我在视频方面遇到了类似的问题。如果导出会话没有关于AVAsset开始时间和持续时间的正确信息，则不会触发完成块。我找到的唯一解决方法是在将每个资产添加到合成轨道（CMTimeRangeMake()）时为每个资产寻找少量时间。这不太理想。

Answer 2

它的工作正常。

[exportSession exportAsynchronouslyWithCompletionHandler:^{
   dispatch_async(dispatch_get_main_queue(), ^{

         switch (exportSession.status) 
         {
                 case AVAssetExportSessionStatusFailed:
                       NSLog(@"AVAssetExportSessionStatusFailed");
                 break;
                 case AVAssetExportSessionStatusCompleted:
                      NSLog(@"AVAssetExportSessionStatusCompleted");
                      [self exportDidFinish:exportSession];
                 break;
                 case AVAssetExportSessionStatusWaiting:
                     NSLog(@"AVAssetExportSessionStatusWaiting");
                 break;
                 default:
                 break;
        }
    });
}];

AVAssetExportSession exportAsynchronouslyWithCompletionHandler：方法未调用

2 个答案: