以下是一个使用AVAssetWriter来编写视频文件的示例，不重新编码原始视频数据：

import AVFoundation

func writeVideoWithoutReencoding(inputURL: URL, outputURL: URL) {
    do {
        let inputAsset = AVURLAsset(url: inputURL)
        let inputVideoTrack = inputAsset.tracks(withMediaType: .video).first!
        
        let assetWriter = try AVAssetWriter(outputURL: outputURL, fileType: .mov)
        
        let outputSettings = [
            AVVideoCodecKey: AVVideoCodecType.h264,
            AVVideoWidthKey: inputVideoTrack.naturalSize.width,
            AVVideoHeightKey: inputVideoTrack.naturalSize.height
        ] as [String : Any]
        
        let videoInput = AVAssetWriterInput(mediaType: .video, outputSettings: outputSettings)
        videoInput.expectsMediaDataInRealTime = false
        assetWriter.add(videoInput)
        
        let videoReader = try AVAssetReader(asset: inputAsset)
        let videoReaderOutput = AVAssetReaderTrackOutput(track: inputVideoTrack, outputSettings: nil)
        videoReader.add(videoReaderOutput)
        
        assetWriter.startWriting()
        videoReader.startReading()
        assetWriter.startSession(atSourceTime: CMTime.zero)
        
        let processingQueue = DispatchQueue(label: "processingQueue")
        videoInput.requestMediaDataWhenReady(on: processingQueue) {
            while videoInput.isReadyForMoreMediaData {
                guard let sampleBuffer = videoReaderOutput.copyNextSampleBuffer() else {
                    videoInput.markAsFinished()
                    assetWriter.finishWriting(completionHandler: {
                        if assetWriter.status == .completed {
                            print("Video writing completed successfully.")
                        } else {
                            print("Video writing failed with error: \(String(describing: assetWriter.error))")
                        }
                    })
                    break
                }
                videoInput.append(sampleBuffer)
            }
        }
    } catch {
        print("Error: \(error)")
    }
}

// Example usage:
let inputURL = URL(fileURLWithPath: "path_to_input_video.mov")
let outputURL = URL(fileURLWithPath: "path_to_output_video.mov")
writeVideoWithoutReencoding(inputURL: inputURL, outputURL: outputURL)

在上述示例中，我们首先创建了一个AVAssetWriter来写入输出视频文件。然后，我们通过AVURLAsset和AVAssetReader来获取输入视频文件的相关信息，并创建了一个AVAssetWriterInput来处理视频数据。

在处理视频数据时，我们使用一个调度队列来异步处理数据。在处理队列上，我们通过AVAssetReaderTrackOutput从输入视频文件中读取样本缓冲区，并将其追加到AVAssetWriterInput中。

最后，我们通过调用assetWriter.finishWriting(completionHandler:)来完成视频写入过程，并检查assetWriter的状态以确保写入成功。