问使用AVPlayerItemVideoOutput: outputMediaDataWillChange快速访问解码帧不被调用

EN

init(frame: CGRect, url: Binding<URL?>) {
        _url = url
        // Setup the player
        player = AVPlayer(url: url.wrappedValue!)
        super.init(frame: frame)
        
        playerLayer.player = player
        playerLayer.videoGravity = .resizeAspect
        layer.addSublayer(playerLayer)
        
        //displayLink = CADisplayLink()
        
        // Setup looping
        player.actionAtItemEnd = .none
        NotificationCenter.default.addObserver(self,
                                               selector: #selector(playerItemDidReachEnd(notification:)),
                                               name: .AVPlayerItemDidPlayToEndTime,
                                               object: player.currentItem)
        
        player.currentItem?.addObserver(self, forKeyPath: #keyPath(AVPlayerItem.status), options: [.old, .new], context: nil)
        
        // Start the movie
        player.play()
    }

override func observeValue(forKeyPath keyPath: String?, of object: Any?, change: [NSKeyValueChangeKey : Any]?, context: UnsafeMutableRawPointer?) {
        if let item = object as? AVPlayerItem {
            if item.status == AVPlayerItem.Status.readyToPlay && item.outputs.count == 0 {
                let settings = [ String(kCVPixelBufferPixelFormatTypeKey): kCVPixelFormatType_24RGB ]
                let output = AVPlayerItemVideoOutput(pixelBufferAttributes: settings)
                
                output.setDelegate(PlayerOutput(output: output), queue: DispatchQueue(label: ""))
                
                player.currentItem?.add(output)
            }
        }
    }

class PlayerOutput : NSObject, AVPlayerItemOutputPullDelegate {
        
        func outputMediaDataWillChange(_ sender: AVPlayerItemOutput) {
            let videoOutput = sender as! AVPlayerItemVideoOutput
            let newPixelBuff = videoOutput.hasNewPixelBuffer(forItemTime: CMTime(seconds: 1, preferredTimescale: 10))
        }
    }

import SwiftUI
import AVFoundation

struct CustomCameraPhotoView: View {

    @State private var image: Image?
    @State private var showingCustomCamera = false
    @State private var showImagePicker = false
    @State private var inputImage: UIImage?
    @State private var url: URL?

    var body: some View {
                ZStack {
                    if url != nil
                    {
                        PlayerView(url: $url)
                    }
                    else
                    {
                        Button(action: {
                            self.showImagePicker = true
                            }) {
                            Text("Select a Video").foregroundColor(.white).font(.headline)
                        }
                        
                    }
                }.edgesIgnoringSafeArea(.all)
            .sheet(isPresented: $showImagePicker,
                   onDismiss: loadImage) {
                    PhotoCaptureView(showImagePicker: self.$showImagePicker, image: self.$image, url: self.$url)
                }.edgesIgnoringSafeArea(.leading).edgesIgnoringSafeArea(.trailing)
    }
    func loadImage() {
        guard let inputImage = inputImage else { return }
        image = Image(uiImage: inputImage)
    }
}

struct PlayerView: UIViewControllerRepresentable {
    
    @Binding var url: URL?
    
    func updateUIViewController(_ uiView: UIViewController, context: UIViewControllerRepresentableContext<PlayerView>) {
    }
    
    func makeCoordinator() ->  PlayerCoordinator{
    //Make Coordinator which will commnicate with the    ImagePickerViewController
        PlayerCoordinator()
    }

    func makeUIViewController(context: Context) -> UIViewController {
        let view = PlayerUIView(frame: .zero, url: $url)
        let controller = PlayerController()
        controller.view = view
        
        return controller
    }
}

class PlayerCoordinator : NSObject, UINavigationControllerDelegate {
    
}

class PlayerController: UIViewController {
    override var shouldAutorotate: Bool {
        return false
    }

    override var supportedInterfaceOrientations: UIInterfaceOrientationMask {
        return .all
    }
}

class PlayerUIView: UIView {
    private let playerLayer = AVPlayerLayer()
    private var playerOutput = PlayerOutput()
    private let _myVideoOutputQueue = DispatchQueue(label: "VideoFrames", qos: .background, attributes: .concurrent, autoreleaseFrequency: .workItem, target: nil)
    
    var displayLink: CADisplayLink?
    var player: AVPlayer
    
    @Binding var url: URL?

    required init?(coder: NSCoder) {
        fatalError("init(coder:) has not been implemented")
    }
    
    init(frame: CGRect, url: Binding<URL?>) {
        _url = url
        // Setup the player
        player = AVPlayer(url: url.wrappedValue!)
        super.init(frame: frame)
        
        playerLayer.player = player
        playerLayer.videoGravity = .resizeAspect
        layer.addSublayer(playerLayer)
        
        let settings = [ String(kCVPixelBufferPixelFormatTypeKey): kCVPixelFormatType_32BGRA ]
        let output = AVPlayerItemVideoOutput(pixelBufferAttributes: settings)
        
        output.setDelegate(self.playerOutput, queue: self._myVideoOutputQueue)
        
        player.currentItem?.add(output)
        
        //displayLink = CADisplayLink()
        
        // Setup looping
        player.actionAtItemEnd = .none
        NotificationCenter.default.addObserver(self,
                                               selector: #selector(playerItemDidReachEnd(notification:)),
                                               name: .AVPlayerItemDidPlayToEndTime,
                                               object: player.currentItem)
        
        player.currentItem?.addObserver(self, forKeyPath: #keyPath(AVPlayerItem.status), options: [.old, .new], context: nil)

        // Start the movie
        player.play()
    }
    
    override func observeValue(forKeyPath keyPath: String?, of object: Any?, change: [NSKeyValueChangeKey : Any]?, context: UnsafeMutableRawPointer?) {
        if let item = object as? AVPlayerItem {
            if item.status == AVPlayerItem.Status.readyToPlay && item.outputs.count == 0 {
                
            }
        }
    }
    
    @objc
    func playerItemDidReachEnd(notification: Notification) {
        self.url = nil
    }

    override func layoutSubviews() {
        super.layoutSubviews()
        playerLayer.frame = bounds
    }
    
    class PlayerOutput : NSObject, AVPlayerItemOutputPullDelegate {
        
        func outputMediaDataWillChange(_ sender: AVPlayerItemOutput) {
            let videoOutput = sender as! AVPlayerItemVideoOutput
            let newPixelBuff = videoOutput.hasNewPixelBuffer(forItemTime: CMTime(seconds: 1, preferredTimescale: 10))
        }
    }
}

struct ImagePicker : UIViewControllerRepresentable {
    @Binding var isShown : Bool
    @Binding var image : Image?
    @Binding var url : URL?
    
    func updateUIViewController(_ uiViewController: UIImagePickerController, context: UIViewControllerRepresentableContext<ImagePicker>)
    {
       //Update UIViewcontrolleer Method
    }
    func makeCoordinator() ->  ImagePickerCoordinator{
    //Make Coordinator which will commnicate with the    ImagePickerViewController
        ImagePickerCoordinator(isShown: $isShown, image: $image, url: $url)
    }
    func makeUIViewController(context: UIViewControllerRepresentableContext<ImagePicker>) -> UIImagePickerController
    {
        let picker = UIImagePickerController()
        picker.sourceType = .photoLibrary
        picker.delegate = context.coordinator
        picker.mediaTypes = ["public.movie"]
        picker.videoQuality = .typeHigh
         return picker
    }
}

class ImagePickerCoordinator : NSObject, UINavigationControllerDelegate, UIImagePickerControllerDelegate{
@Binding var isShown : Bool
@Binding var image : Image?
    @Binding var url: URL?
    init(isShown : Binding<Bool>, image: Binding<Image?>, url: Binding<URL?>) {
      _isShown = isShown
      _image = image
      _url = url
   }
//Selected Image
   func imagePickerController(_ picker: UIImagePickerController, didFinishPickingMediaWithInfo info: [UIImagePickerController.InfoKey : Any]) {
    let uiImage = info[UIImagePickerController.InfoKey.mediaURL]   as! URL
    url = uiImage
//image = Image(uiImage: uiImage)
   isShown = false
}
//Image selection got cancel
   func imagePickerControllerDidCancel(_ picker: UIImagePickerController) {
   isShown = false
   }
}

struct PhotoCaptureView: View {
   @Binding var showImagePicker : Bool
   @Binding var image : Image?
    @Binding var url : URL?
 
   var body: some View {
    ImagePicker(isShown: $showImagePicker, image: $image, url: $url)
   }
}

struct ContentView_Previews: PreviewProvider {
    static var previews: some View {
        CustomCameraPhotoView()
    }
}