AVAssetExportPreset类型的AVAssetExportSession问题
问题描述:
我使用此扩展名将视频文件从AVAsset
保存到tmp文件夹。问题是,当我使用AVAssetExportPresetHighestQuality
类型的视频文件无法由于这个原因,保存:AVAssetExportPreset类型的AVAssetExportSession问题
错误域= AVFoundationErrorDomain代码= -11800“的操作可能 无法完成”的UserInfo = {NSUnderlyingError = {0x1748482e0错误 域= NSOSStatusErrorDomain代码= -12780 “(空)”}, NSLocalizedFailureReason =出现未知错误(-12780), NSLocalizedDescription =操作无法完成}
还有些时候,甚至当我我正在使用AVAssetExportPresetHighestQuality
它ves视频,但以随机顺序。
extension AVAsset {
func write(to url: URL, success: @escaping() ->(), failure: @escaping (Error) ->()) {
guard let exportSession = AVAssetExportSession(asset: self, presetName: AVAssetExportPresetMediumQuality) else {
let error = NSError(domain: "domain", code: 0, userInfo: nil)
failure(error)
return
}
exportSession.outputFileType = AVFileTypeMPEG4
exportSession.outputURL = url
exportSession.exportAsynchronously {
switch exportSession.status {
case .completed:
success()
case .unknown, .waiting, .exporting, .failed, .cancelled:
let error = NSError(domain: "domain", code: 0, userInfo: nil)
failure(error)
}
}
}
}
答
此问题与AVAsset
组件的长度错误有关。由于某些原因,AVAsset
曲目的视频和音频曲目的持续时间不同,这是主要问题。
要解决此问题,我使用了AVAsset
的自定义扩展。此功能将基于视频和音频轨道创建新的AVAsset
,其条件将修复持续时间问题。因此从normalizingMediaDuration()
获得的AVAsset
可以成功导出。
extension AVAsset {
func normalizingMediaDuration() -> AVAsset? {
let mixComposition : AVMutableComposition = AVMutableComposition()
var mutableCompositionVideoTrack : [AVMutableCompositionTrack] = []
var mutableCompositionAudioTrack : [AVMutableCompositionTrack] = []
let totalVideoCompositionInstruction : AVMutableVideoCompositionInstruction = AVMutableVideoCompositionInstruction()
guard let video = tracks(withMediaType: AVMediaTypeVideo).first else {
return nil
}
guard let audio = tracks(withMediaType: AVMediaTypeAudio).first else {
return nil
}
mutableCompositionVideoTrack.append(mixComposition.addMutableTrack(withMediaType: AVMediaTypeVideo, preferredTrackID: kCMPersistentTrackID_Invalid))
mutableCompositionAudioTrack.append(mixComposition.addMutableTrack(withMediaType: AVMediaTypeAudio, preferredTrackID: kCMPersistentTrackID_Invalid))
let duration = video.timeRange.duration.seconds > audio.timeRange.duration.seconds ? audio.timeRange.duration : video.timeRange.duration
do{
try mutableCompositionVideoTrack[0].insertTimeRange(CMTimeRangeMake(kCMTimeZero,duration), of: video, at: kCMTimeZero)
try mutableCompositionAudioTrack[0].insertTimeRange(CMTimeRangeMake(kCMTimeZero, duration), of: audio, at: kCMTimeZero)
}catch{
return nil
}
totalVideoCompositionInstruction.timeRange = CMTimeRangeMake(kCMTimeZero,duration)
return mixComposition
}
}