无法使用AVVideoCompositionCoreAnimationTool

时间：2018-09-20 14:34:56

标签： swift calayer cabasicanimation avassetexportsession avvideocomposition

更新6： 我已经设法完全解决了我的问题，但是我仍然希望得到比我猜测的更好的解释，如果我不正确，那是它不起作用的原因

我一直试图在视频上制作一个精灵表动画，但是每次导出视频时，最终结果都是我开始的示例视频。

这是我的代码：

首先启动我的自定义CALayer来处理我自己的Sprite工作表

class SpriteLayer: CALayer {
    var frameIndex: Int

    override init() {
        // Using 0 as a default state
        self.frameIndex = 0
        super.init()
    }

    required init?(coder aDecoder: NSCoder) {
        self.frameIndex = 0
        super.init(coder: aDecoder)
    }

    override func display() {
        let currentFrameIndex = self.frameIndex
        if currentFrameIndex == 0 {
            return
        }
        let frameSize = self.contentsRect.size
        self.contentsRect = CGRect(x: 0, y: CGFloat(currentFrameIndex - 1) * frameSize.height, width: frameSize.width, height: frameSize.height)
    }

    override func action(forKey event: String) -> CAAction? {
        if event == "contentsRect" {
            return nil
        }
        return super.action(forKey: event)
    }

    override class func needsDisplay(forKey key: String) -> Bool {
        return key == "frameIndex"
    }
}

Gif是没有花哨的基础类，并且工作正常。 gif.Strip是代表gif的垂直精灵表格的UIImage。

现在出现了应该导出新视频的方法（它是用于导出的较大类的一部分。

func convertAndExport(to url :URL , completion: @escaping () -> Void ) {
        // Get Initial info and make sure our destination is available
        self.outputURL = url
        let stripCgImage = self.gif.strip!.cgImage!
        // This is used to time how long the export took
        let start = DispatchTime.now()
        do {
            try FileManager.default.removeItem(at: outputURL)
        } catch {
            print("Remove Error: \(error.localizedDescription)")
            print(error)
        }
        // Find and load "sample.mp4" as a AVAsset
        let videoPath = Bundle.main.path(forResource: "sample", ofType: "mp4")!
        let videoUrl = URL(fileURLWithPath: videoPath)
        let videoAsset = AVAsset(url: videoUrl)
        // Start a new mutable Composition with the same base video track
        let mixComposition = AVMutableComposition()
        let compositionVideoTrack = mixComposition.addMutableTrack(withMediaType: .video, preferredTrackID: kCMPersistentTrackID_Invalid)!
        let clipVideoTrack = videoAsset.tracks(withMediaType: .video).first!
        do {
            try compositionVideoTrack.insertTimeRange(CMTimeRangeMake(kCMTimeZero, videoAsset.duration), of: clipVideoTrack, at: kCMTimeZero)
        } catch {
            print("Insert Error: \(error.localizedDescription)")
            print(error)
            return
        }
        compositionVideoTrack.preferredTransform = clipVideoTrack.preferredTransform
        // Quick access to the video size
        let videoSize = clipVideoTrack.naturalSize
        // Setup CALayer and it's animation
        let aLayer = SpriteLayer()
        aLayer.contents = stripCgImage
        aLayer.frame = CGRect(x: 0, y: 0, width: videoSize.width, height: videoSize.height)
        aLayer.opacity = 1.0
        aLayer.masksToBounds = true
        aLayer.bounds = CGRect(x: 0, y: 0, width: videoSize.width, height: videoSize.height)
        aLayer.contentsRect = CGRect(x: 0, y: 0, width: 1, height: 1.0 / 3.0)
        let spriteAnimation = CABasicAnimation(keyPath: "frameIndex")
        spriteAnimation.fromValue = 1
        spriteAnimation.toValue = 4
        spriteAnimation.duration = 2.25
        spriteAnimation.repeatCount = .infinity
        spriteAnimation.autoreverses = false
        spriteAnimation.beginTime = AVCoreAnimationBeginTimeAtZero
        aLayer.add(spriteAnimation, forKey: nil)
        // Setup Layers for AVVideoCompositionCoreAnimationTool
        let parentLayer = CALayer()
        let videoLayer = CALayer()
        parentLayer.frame = CGRect(x: 0, y: 0, width: videoSize.width, height: videoSize.height)
        videoLayer.frame = CGRect(x: 0, y: 0, width: videoSize.width, height: videoSize.height)
        parentLayer.addSublayer(videoLayer)
        parentLayer.addSublayer(aLayer)
        // Create the mutable video composition
        let videoComp = AVMutableVideoComposition()
        videoComp.renderSize = videoSize
        videoComp.frameDuration = CMTimeMake(1, 30)
        videoComp.animationTool = AVVideoCompositionCoreAnimationTool(postProcessingAsVideoLayer: videoLayer, in: parentLayer)
        // Set the video composition to apply to the composition's video track
        let instruction = AVMutableVideoCompositionInstruction()
        instruction.timeRange = CMTimeRangeMake(kCMTimeZero, mixComposition.duration)
        let videoTrack = mixComposition.tracks(withMediaType: .video).first!
        let layerInstruction = AVMutableVideoCompositionLayerInstruction(assetTrack: videoTrack)
        instruction.layerInstructions = [layerInstruction]
        videoComp.instructions = [instruction]
        // Initialize export session
        let assetExport = AVAssetExportSession(asset: mixComposition, presetName: AVAssetExportPresetPassthrough)!
        assetExport.videoComposition = videoComp
        assetExport.outputFileType = AVFileType.mp4
        assetExport.outputURL = self.outputURL
        assetExport.shouldOptimizeForNetworkUse = true
        // Export
        assetExport.exportAsynchronously {
            let status = assetExport.status
            switch status {
            case .failed:
                print("Export Failed")
                print("Export Error: \(assetExport.error!.localizedDescription)")
                print(assetExport.error!)
            case .unknown:
                print("Export Unknown")
            case .exporting:
                print("Export Exporting")
            case .waiting:
                print("Export Waiting")
            case .cancelled:
                print("Export Cancelled")
            case .completed:
                let end = DispatchTime.now()
                let nanoTime = end.uptimeNanoseconds - start.uptimeNanoseconds
                let timeInterval = Double(nanoTime) / 1_000_000_000
                // Function is now over, we can print how long it took
                print("Time to generate video: \(timeInterval) seconds")
                completion()
            }
        }
}

编辑： 我的代码基于以下链接

更新1： 我尝试删除代码中的CABasicAnimation部分，并尝试使用CALayer，但无济于事。我什至无法显示图像。 为了进行测试，我尝试在Xcode Playground中使用CAKeyframeAnimation上的contentsRect对此Sprite工作表进行动画处理，并且效果很好，所以我认为问题不在于CABasicAnimation，甚至可能与CALayer本身。我真的可以为此提供一些帮助，因为我不明白为什么我什至无法在导出的示例视频上显示图像。

更新2： 为了回应Matt的评论，我尝试了一点点忘记这张Sprite表，将其更改为CATextLayer，但仍然看不到我的视频（它有深色图像，因此白色文字应该是完全可见的） 

let aLayer = CATextLayer()
aLayer.string = "This is a test"
aLayer.fontSize = videoSize.height / 6
aLayer.alignmentMode = kCAAlignmentCenter
aLayer.foregroundColor = UIColor.white.cgColor
aLayer.bounds = CGRect(x: 0, y: 0, width: videoSize.width, height: videoSize.height / 6)

更新3： 根据Matt的要求，我尝试将parentLayer.addSublayer(aLayer)更改为videoLayer.addSublayer(aLayer)，但仍然没有任何变化，但是我想了很多，因为AVVideoCompositionCoreAnimationTool的{​​{3}}如下

convenience init(postProcessingAsVideoLayer videoLayer: CALayer, 
              in animationLayer: CALayer)

表示我的parentLayer是animationLayer，可能意味着任何动画都应在此层中完成。

更新4： 我开始疯了，我现在已经放弃了显示文本或动画图像的想法，我只是想以任何可能的方式影响视频，所以我将aLayer更改为： 

let aLayer = CALayer()
aLayer.frame = CGRect(x: 0, y: 0, width: videoSize.width, height: videoSize.height)
aLayer.backgroundColor = UIColor.white.cgColor

好吧，这绝对没有任何作用，我仍然可以在我的outputUrl上获得示例视频（如果您想“玩”，我会在操场上用以下代码进行测试）

import PlaygroundSupport
import UIKit
import Foundation
import AVFoundation

func convertAndExport(to url :URL , completion: @escaping () -> Void ) {
    let start = DispatchTime.now()
    do {
        try FileManager.default.removeItem(at: url)
    } catch {
        print("Remove Error: \(error.localizedDescription)")
        print(error)
    }

    let videoPath = Bundle.main.path(forResource: "sample", ofType: "mp4")!
    let videoUrl = URL(fileURLWithPath: videoPath)
    let videoAsset = AVURLAsset(url: videoUrl)
    let mixComposition = AVMutableComposition()
    let compositionVideoTrack = mixComposition.addMutableTrack(withMediaType: .video, preferredTrackID: kCMPersistentTrackID_Invalid)!
    let clipVideoTrack = videoAsset.tracks(withMediaType: .video).first!

    do {
        try compositionVideoTrack.insertTimeRange(CMTimeRangeMake(kCMTimeZero, videoAsset.duration), of: clipVideoTrack, at: kCMTimeZero)
    } catch {
        print("Insert Error: \(error.localizedDescription)")
        print(error)
        return
    }
    compositionVideoTrack.preferredTransform = clipVideoTrack.preferredTransform
    let videoSize = clipVideoTrack.naturalSize
    print("Video Size Detected: \(videoSize.width) x \(videoSize.height)")

    let aLayer = CALayer()
    aLayer.frame = CGRect(x: 0, y: 0, width: videoSize.width, height: videoSize.height)
    aLayer.backgroundColor = UIColor.white.cgColor

    let parentLayer = CALayer()
    let videoLayer = CALayer()
    parentLayer.frame = CGRect(x: 0, y: 0, width: videoSize.width, height: videoSize.height)
    videoLayer.frame = CGRect(x: 0, y: 0, width: videoSize.width, height: videoSize.height)
    parentLayer.addSublayer(videoLayer)
    parentLayer.addSublayer(aLayer)
    aLayer.setNeedsDisplay()
    let videoComp = AVMutableVideoComposition()
    videoComp.renderSize = videoSize
    videoComp.frameDuration = CMTimeMake(1, 30)
    videoComp.animationTool = AVVideoCompositionCoreAnimationTool(postProcessingAsVideoLayer: videoLayer, in: parentLayer)

    let instruction = AVMutableVideoCompositionInstruction()
    instruction.timeRange = CMTimeRangeMake(kCMTimeZero, mixComposition.duration)
    let videoTrack = mixComposition.tracks(withMediaType: .video).first!
    let layerInstruction = AVMutableVideoCompositionLayerInstruction(assetTrack: videoTrack)
    instruction.layerInstructions = [layerInstruction]
    videoComp.instructions = [instruction]

    let assetExport = AVAssetExportSession(asset: mixComposition, presetName: AVAssetExportPresetPassthrough)!
    assetExport.videoComposition = videoComp
    assetExport.outputFileType = AVFileType.mp4
    assetExport.outputURL = url
    assetExport.shouldOptimizeForNetworkUse = true

    assetExport.exportAsynchronously {
        let status = assetExport.status
        switch status {
        case .failed:
            print("Export Failed")
            print("Export Error: \(assetExport.error!.localizedDescription)")
            print(assetExport.error!)
        case .unknown:
            print("Export Unknown")
        case .exporting:
            print("Export Exporting")
        case .waiting:
            print("Export Waiting")
        case .cancelled:
            print("Export Cancelled")
        case .completed:
            let end = DispatchTime.now()
            let nanoTime = end.uptimeNanoseconds - start.uptimeNanoseconds
            let timeInterval = Double(nanoTime) / 1_000_000_000
            print("Time to generate video: \(timeInterval) seconds")
            completion()
        }
    }
}

let outputUrl = FileManager.default.temporaryDirectory.appendingPathComponent("test.mp4")
convertAndExport(to: outputUrl) {
    print(outputUrl)
}

请有人帮助我了解我在做什么错...

更新5： 我正在运行从iPad Air 2（因此没有模拟器）进行的游乐场测试以外的所有操作，因为我使用相机拍摄照片，然后将它们缝成一张精灵纸，然后计划将其通过电子邮件发送的视频动画化。我开始进行Playground测试是因为iPad上的每项测试都要求我经历整个应用周期（倒数，照片，表格，电子邮件发送/接收）

1 个答案:

答案 0 :(得分：1)

好吧，终于让它按我一直希望的那样工作了。

首先，即使他删除了他的评论，也要感谢Matt链接到一个有效的示例，该示例帮助我整理了代码的错误之处。

  • 先行
let assetExport = AVAssetExportSession(asset: mixComposition, presetName: AVAssetExportPresetPassthrough)!

我需要使用AVAssetExportPresetHighestQuality而不是AVAssetExportPresetPassthrough。我的猜测是直通预设意味着您不进行任何重新编码，因此将其设置为最高（由于导出的视频尺寸超过400x400，因此设置为中等），这样我才能真正对视频进行重新编码。我猜这是在阻止导出的视频包含我正在尝试的CALayer中的任何内容（甚至将视频覆盖为白色）。

  • 其次（不确定是否确实会影响，但我稍后再试）
parentLayer.addSublayer(aLayer)

我将其替换为：

videoLayer.addSublayer(aLayer)

不确定这是否真的很重要，但我的理解是，这实际上是AVVideoCompositionCoreAnimationTool和parentLayer的动画层，只是一个容器，并不意味着要包含更多内容，但是我可能错了

  • 我做了第三次改变
let spriteAnimation = CABasicAnimation(keyPath: "frameIndex")
spriteAnimation.fromValue = 1
spriteAnimation.toValue = 4
spriteAnimation.duration = 2.25
spriteAnimation.repeatCount = .infinity
spriteAnimation.autoreverses = false
spriteAnimation.beginTime = AVCoreAnimationBeginTimeAtZero
aLayer.add(spriteAnimation, forKey: nil)

我将其更改为此：

let animation = CAKeyframeAnimation(keyPath: #keyPath(CALayer.contentsRect))
animation.duration = 2.25
animation.calculationMode = kCAAnimationDiscrete
animation.repeatCount = .infinity
animation.values = [
    CGRect(x: 0, y: 0, width: 1, height: 1/3.0),
    CGRect(x: 0, y: 1/3.0, width: 1, height: 1/3.0),
    CGRect(x: 0, y: 2/3.0, width: 1, height: 1/3.0)
    ] as [CGRect]
animation.beginTime = AVCoreAnimationBeginTimeAtZero
animation.fillMode = kCAFillModeBackwards
animation.isRemovedOnCompletion = false
aLayer.add(animation, forKey: nil)

此更改主要是删除了我为Sprite表创建的自定义动画（因为它始终是相同的，因此我首先想要一个工作示例，然后将其归纳并可能将其添加到我的私有UI Pod中）。但最重要的是，animation.isRemovedOnCompletion = false我注意到删除它可以使动画完全不在导出的视频上播放。因此，对于CABasicAnimation导出后未在视频上设置动画的任何人，请尝试查看isRemovedOnCompletion在动画上的设置是否正确。

我认为这几乎就是我所做的所有改变。

尽管我从技术上回答了我的问题，但我的赏识仍然是了解AVVideoCompositionCoreAnimationTool和AVAssetExport的工作方式，以及如果有人有兴趣解释的话，为什么我必须进行更改以最终使其生效。

再次感谢马特，您向我展示了您的工作方式，从而帮助了我。

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