Question

我有一个功能，可以将视频网址作为输入，并在完成后输出已编辑视频的输出网址。

基本上该功能会创建一个方形视频，如果视频长度超过30秒，则视频长度为30秒。

这是功能：

func compressVideo(inputURL: URL, outputURL: URL, handler:@escaping (_ exportSession: AVAssetExportSession?)-> Void) {
    let urlAsset = AVURLAsset(url: inputURL as URL, options: nil)
    guard let exportSession = AVAssetExportSession(asset: urlAsset, presetName: AVAssetExportPresetMediumQuality) else {
        handler(nil)
        return
    }
     let clipVideoTrack = urlAsset.tracks( withMediaType: AVMediaType.video ).first! as AVAssetTrack
    let composition = AVMutableComposition()
    composition.addMutableTrack(withMediaType: AVMediaType.video, preferredTrackID: CMPersistentTrackID())

    let videoComposition = AVMutableVideoComposition()
    videoComposition.renderSize = CGSize( width: clipVideoTrack.naturalSize.height, height: clipVideoTrack.naturalSize.height )
    videoComposition.frameDuration = CMTimeMake(1, 30)

    let transformer = AVMutableVideoCompositionLayerInstruction(assetTrack: clipVideoTrack)

    let instruction = AVMutableVideoCompositionInstruction()
    instruction.timeRange = CMTimeRangeMake(kCMTimeZero, CMTimeMakeWithSeconds(60, 30))


    let transform1: CGAffineTransform = CGAffineTransform(translationX: clipVideoTrack.naturalSize.height, y: (clipVideoTrack.naturalSize.width - clipVideoTrack.naturalSize.height) / 2)
    let transform2 = transform1.rotated(by: .pi/2)
    let finalTransform = transform2


    transformer.setTransform(finalTransform, at: kCMTimeZero)

    instruction.layerInstructions = [transformer]
    videoComposition.instructions = [instruction]

    let timescale = urlAsset.duration.timescale
    let duration = CMTimeGetSeconds(urlAsset.duration)
    if (duration < 31.0) {
        print("minore")
    } else {
        let startTime = CMTimeMakeWithSeconds(0, timescale)
        let stopTime = CMTimeMakeWithSeconds(30, timescale)
        let exportTimeRange = CMTimeRangeFromTimeToTime(startTime, stopTime)
        exportSession.timeRange = exportTimeRange
        print("maggiore")
    }

    exportSession.outputURL = outputURL
    exportSession.outputFileType = AVFileType.mov
    exportSession.videoComposition = videoComposition
    exportSession.shouldOptimizeForNetworkUse = true
    exportSession.exportAsynchronously { () -> Void in
        handler(exportSession)
    }
}

到目前为止，我只在模拟器上测试过它。该功能工作正常，但我注意到cpu的使用非常高。它达到了300％甚至更多。内存使用量高达414 MB。我错过了什么吗？是应该怎么样或者我犯了一些错误？有没有办法减少CPU使用量，从而减少等待时间。我是swift的新手，这是我第一次使用视频和AVFoundation。

谢谢。

Swift - 修剪视频和裁剪到方块CPU使用率

0 个答案: