问题似乎与AVAssetExportPresetPassthrough(可能是与处理AAC的组合)有关

Issue seems to be related to AVAssetExportPresetPassthrough (and a combination of dealing with an AAC, maybe)

更改为AVAssetExportPresetLowQuality或AVAssetExportPresetHighestQuality，并将视频/音频正确混合为一个.同样，这只是IOS 13问题，并且很可能是错误.

Changing to AVAssetExportPresetLowQuality or AVAssetExportPresetHighestQuality and the video/audio are properly muxed into one. Again, this is just an IOS 13 issue, and likely a bug.