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我创建了这个函数来修剪音频文件的特定部分。在函数中，我将两个 AVMetadataItems 写入新文件。稍后我试图通过使用 AvURlAsset 敲击 URL 然后访问 AVAsset 元数据 /commonMetadata 来访问这些项目，并且两者都不包含我之前添加的项目。

所以我在导出文件之前检查了发生了什么，即使我给了 exporter.metadata 一个数组哦 AVMetadataitem，它在导出之前似乎仍然为零。

任何人都知道是什么问题？

func trimFromOffSetWithDuration(_ from: Date, startOffSet: TimeInterval, duration: TimeInterval, newfileName: String, file: URL, completion: fileExportaionBlock?) {

    if let asset = AVURLAsset(url: file) as AVAsset? {

        let trimmedFileUrl = documentsDirectory().appendingPathComponent(newfileName)

        let exporter = AVAssetExportSession(asset: asset, presetName: AVAssetExportPresetAppleM4A)
        exporter?.outputFileType = AVFileTypeAppleM4A
        exporter?.outputURL = trimmedFileUrl

        let start = CMTimeMake(Int64(startOffSet), 1)
        let end = CMTimeMake(Int64(startOffSet + duration), 1)
        exporter?.timeRange = CMTimeRangeFromTimeToTime(start, end)

        let typeMetaDataItem = AVMutableMetadataItem()
        typeMetaDataItem.key = AVMetadataCommonKeyDescription as  NSCopying & NSObjectProtocol
        typeMetaDataItem.keySpace = AVMetadataKeySpaceCommon
        typeMetaDataItem.value = TrackType.recording.rawValue as NSCopying & NSObjectProtocol

        let dateMetaDataItem = AVMutableMetadataItem()
        dateMetaDataItem.key = AVMetadataCommonKeyCreationDate as NSCopying & NSObjectProtocol
        dateMetaDataItem.keySpace = AVMetadataKeySpaceCommon
        dateMetaDataItem.value = from as NSCopying & NSObjectProtocol

        exporter?.metadata? = [dateMetaDataItem, typeMetaDataItem]
        exporter?.exportAsynchronously { handler in

            if exporter?.status != AVAssetExportSessionStatus.completed {
                print("Error while exporting \(exporter?.error?.localizedDescription ?? "unknown")")
                completion?(nil)
                return
            }
        }

        completion?(trimmedFileUrl)
    }
}
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1 回答 1

0

您应该移动completion?(trimmedFileUrl)到exportAsynchronously.

于 2017-08-29T12:05:20.507 回答