iOS - AVAssetExportSession 未知错误 -12769

Question

似乎 AVFoundation 无法接受我的某个视频。我真的不知道为什么。它适用于其他视频，但不适用于这个。

我什至没有修改视频，我只是对视频轨道进行合成，并使用预设的“AVAssetExportPresetHighestQuality”将其导出。

我收到此错误：

Error Domain=AVFoundationErrorDomain Code=-11800 "The operation could not be completed" UserInfo={NSUnderlyingError=0x60000045a8e0 {Error Domain=NSOSStatusErrorDomain Code=-12769 "(null)"}, NSLocalizedFailureReason=An unknown error occurred (-12769), NSLocalizedDescription=The operation could not be completed}

您知道我的代码是否有问题，还是 AVFoundation 不支持视频？

这是 Github 上的项目（它只是将视频导出到相机胶卷）：

https://github.com/moonshaped/ExportSessionCrash

或者如果你不想使用 Github：

这是视频：

Dropbox 链接：https://www.dropbox.com/s/twgah26gqgsv9y9/localStoreTempVideoPath.mp4?dl=0

或WeTransfer链接：https://wetransfer.com/downloads/8f8ab257068461a2c9a051542610725220170606122640/8d934c

这是代码：

- (void)exportVideo:(AVAsset *)videoAsset
      videoDuration:(Float64)videoAssetDuration
                 to:(NSString *)resultPath{

    [Utilities deleteFileIfExists:resultPath];

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

    int timeScale = 100000;
    int videoDurationI = (int) (videoAssetDuration * (float) timeScale);
    CMTime videoDuration = CMTimeMake(videoDurationI, timeScale);
    CMTimeRange videoTimeRange = CMTimeRangeMake(kCMTimeZero, videoDuration);

    NSArray<AVAssetTrack *> *videoTracks = [videoAsset tracksWithMediaType:AVMediaTypeVideo];
    AVAssetTrack *videoTrack = [videoTracks objectAtIndex:0];

    [compositionVideoTrack insertTimeRange:videoTimeRange
                                   ofTrack:videoTrack
                                    atTime:kCMTimeZero
                                     error:nil];

    NSURL *outptVideoUrl = [NSURL fileURLWithPath:resultPath];
    self.exporter = [[AVAssetExportSession alloc] initWithAsset:mainComposition
                                                     presetName:AVAssetExportPresetHighestQuality];

    self.exporter.outputURL = outptVideoUrl;
    self.exporter.outputFileType = AVFileTypeMPEG4;
    self.exporter.shouldOptimizeForNetworkUse = YES;

    [self.exporter exportAsynchronouslyWithCompletionHandler:^{
        dispatch_async(dispatch_get_main_queue(), ^{
            switch (self.exporter.status) {
                case AVAssetExportSessionStatusFailed:{
                    @throw [NSException exceptionWithName:@"failed export"
                                                   reason:[self.exporter.error description]
                                                 userInfo:nil];
                }
                case AVAssetExportSessionStatusCancelled:
                    @throw [NSException exceptionWithName:@"cancelled export"
                                                   reason:@"Export cancelled"
                                                 userInfo:nil];

                case AVAssetExportSessionStatusCompleted: {
                    NSLog(@"Export finished");
                }
                    break;

                default:
                    break;
            }
        });
    }];
}

Answer 1

我做了一个实验，得出了这个结论。如果您从 videoTimeRange 减少 1 毫秒或更多毫秒，那么它将起作用。尝试替换下面的代码块：

int timeScale = 100000;
Float64 seconds = CMTimeGetSeconds([videoAsset duration]) - 0.001;
NSUInteger videoDurationI = (NSUInteger) (seconds * (float) timeScale);
CMTime videoDuration = CMTimeMake(videoDurationI, timeScale);
CMTimeRange videoTimeRange = CMTimeRangeMake(kCMTimeZero, videoDuration);

Answer 2

您尝试测试的设备无法对其进行解码。请在一些较新的设备上尝试，例如iPhone 6。我在 iPad 模拟器 iOS10.3 上测试了你的媒体，它在那里运行良好，所以它一定与编码有关。