无法对整个视频应用 CIFilter

如何解决无法对整个视频应用 CIFilter

我正在尝试对视频应用过滤器，然后将其显示在 UIview 上。 但它只应用于一帧，并没有显示在整个视频上。

下面是我的

    let filter = CIFilter(name: "CISepiaTone")!
    let asset = AVAsset(url: videoURL)
    let composition = AVVideoComposition(asset: asset,applyingCIFiltersWithHandler: { request in

        // Clamp to avoid blurring transparent pixels at the image edges
            let source = request.sourceImage.clampedToExtent()
        filter.setValue(source,forKey: kCIInputimageKey)

       

        // Crop the blurred output to the bounds of the original image
            let output = filter.outputimage!.cropped(to: request.sourceImage.extent)

        // Provide the filter output to the composition
        request.finish(with: output,context: nil)
        
        
        
    })
    let playerItem = AVPlayerItem(asset: asset)
                playerItem.videoComposition = composition
                    let player = AVPlayer(playerItem: playerItem)
                    let layer: AVPlayerLayer = AVPlayerLayer(player: player)
                    layer.backgroundColor = UIColor.white.cgColor
                    layer.frame = CGRect(x: 0,y: 0,width: videoView.frame.width,height: videoView.frame.height)
                    layer.videoGravity = AVLayerVideoGravity.resizeAspectFill
                    videoView.layer.sublayers?.forEach({$0.removeFromSuperlayer()})
                    videoView.layer.addSublayer(layer)