swift - 使用 replaceCurrentItem() 时 AVPlayer 闪烁 - Swift - 以编程方式

Question

我正在设置一个 AVPlayer在 UIView这样:

fileprivate func setUpAVPlayer(){
    
    self.cardModel?.urlStrings?.forEach({ (urlString) in
        
        guard let url = URL(string: urlString) else { return }
        let asset = AVAsset(url: url)
        let playerItem = AVPlayerItem(asset: asset, automaticallyLoadedAssetKeys: nil)
        playerItem.addObserver(self, forKeyPath: #keyPath(AVPlayerItem.status), options: [.old, .new], context: nil)
        self.playerItemArray.append(playerItem)
    })
    player = AVPlayer(playerItem: playerItemArray[0])
}

在 layoutSubviews我布置了显示播放器的 playerLayer:

let playerLayer = AVPlayerLayer(player: player)
playerLayer.videoGravity = .resizeAspectFill
self.playerView.layer.insertSublayer(playerLayer, at: 0)
playerLayer.frame = playerView.bounds

在某个事件中，我更改了玩家的当前项目:

fileprivate func goToNextVideo(){
    counter = counter+1
    counter = min(playerItemArray.count-1, counter)
    
    self.player?.replaceCurrentItem(with: self.playerItemArray[self.counter])
    self.player?.seek(to: .zero)
    self.player?.play()
}

当我更改项目时，过渡不平滑，我可以看到显示 view 的闪光灯。 下面 .有一些我不明白的地方:

为什么如果我预装了所有 AVPlayerItems在开始时(当我循环所有 urls 字符串时)我仍然需要等待它们成为 currentItem 时被加载。的AVPlayer？

关于闪烁效果的问题我在网上搜索了下没有解决，于是仔细查看了AVPlayer的行为。每当更改 Item 时，我都会以这种方式描述它:

第一 它显示了一个白色的 View (见下图)
第二 它显示了将要显示的视频帧(更多或更少的时间帧位于视频的一半)
第三 它实际上显示了视频
这种行为真的很烦人，我想知道如何解决它。

Answer 1

import UIKit
import GPUImage
import AVFoundation

class ViewController: UIViewController {

    lazy var movie: GPUImageMovie = {
        let movie = GPUImageMovie()
        movie.yuvConversionSetup()
        movie.addTarget(imageView)
        return movie
    }()
    
    lazy var imageView: GPUImageView = {
        let view = GPUImageView()
        view.setBackgroundColorRed(1, green: 1, blue: 1, alpha: 1)
        return view
    }()
    
    lazy var player: AVPlayer = {
        let player = AVPlayer()
        return player
    }()
    
    lazy var videoURLs: [URL] = {
        return [
            resource(filename: "video0.mp4"),
            resource(filename: "video1.mp4"),
            resource(filename: "video2.mp4"),
            resource(filename: "video3.mp4"),
        ].compactMap({ $0 })
    }()
    
    lazy var button: UIButton = {
        let button = UIButton()
        button.setTitle("replaceCurrentItem", for: .normal)
        button.setTitleColor(.gray, for: .normal)
        button.addTarget(self, action: #selector(action(_:)), for: .touchUpInside)
        return button
    }()
    
    var index = 0
    
    override func viewDidLoad() {
        super.viewDidLoad()
        view.backgroundColor = .white
        view.addSubview(imageView)
        view.addSubview(button)
        imageView.frame = view.bounds
        button.frame = CGRect(x: 0, y: view.bounds.maxY - 100, width: view.bounds.width, height: 44)
    }

    func resource(filename: String) -> URL? {
        return Bundle.main.url(forResource: filename, withExtension: nil)
    }
    
    @objc func action(_ sender: UIButton) {
        if let url = getVideoURL() {
            player.pause()
            movie.endProcessing()
            movie.playerItem = AVPlayerItem(url: url)
            player.replaceCurrentItem(with: movie.playerItem)
            player.play()
            movie.startProcessing()
        }
    }
    
    func getVideoURL() -> URL? {
        if videoURLs.indices.contains(index) {
            let url = videoURLs[index]
            index = (index + 1) % videoURLs.count
            return url
        } else {
            return nil
        }
    }
    
}

Podfile:

platform :ios, '9.0'
source 'https://github.com/CocoaPods/Specs.git'

target 'Test' do
  use_frameworks!
  pod 'GPUImage'
end

当您调用 replaceCurrentItem ，它将清理图像缓冲区，然后等待渲染下一帧。所以，关键是要在屏幕上保留最后一帧:而不是使用 AVPlayerLayer要渲染视频帧，您可以使用 AVPlayerItemVideoOutput获取帧并使用 OpenGL ES(或 Metal)进行渲染。您还可以决定何时清理图像缓冲区。