title: I want to apply CIFilter on video and save that filter applied video. [export taking too much time]
body: <p><strong>I want to apply CIFilter on video and save that filter applied video.</strong></p>
  
  <p>I am using AVMutableVideoComposition (also tried with AVVideoComposition) for apply filter on video and its working fine with AVPlayer but when i am exporting filtered video then it takes too much time to save locally (20sec video taking arround 6-8 min). Please guide me what i am doing wrong... 
  Thankyou !</p>
  
  <pre><code>let item = AVPlayerItem(asset: currentAsset!)
      let videoComposition = AVMutableVideoComposition(asset: currentAsset!) { request in
          let filter = CIFilter(name: "CIColorInvert")!
          let source = request.sourceImage.clampedToExtent()
          filter.setValue(source, forKey: kCIInputImageKey)
  
          let output = filter.outputImage!.cropped(to: request.sourceImage.extent)
  
          // Provide the filter output to the composition
          request.finish(with: output, context: nil)
      }
      item.videoComposition = videoComposition
      self.player.replaceCurrentItem(with: item)
  
      let exporter = AVAssetExportSession(asset: item.asset, presetName: AVAssetExportPresetHighestQuality)
      exporter?.videoComposition = videoComposition
  
      exporter?.outputFileType = .mp4
      let filename = "filename.mp4"
  
      let documentsDirectory = FileManager.default.urls(for: FileManager.SearchPathDirectory.documentDirectory, in: FileManager.SearchPathDomainMask.userDomainMask).last!
      let outputURL = documentsDirectory.appendingPathComponent(filename)
      exporter?.outputURL = outputURL
      exporter?.exportAsynchronously(completionHandler: {
          guard exporter?.status == .completed else {
              print("export failed: \(exporter?.error)")
              return
          }
          print("done: ",outputURL)
      }
      )
  </code></pre>