Video 将更改后的视频保存到Swift 3中的摄像机卷
为了在Swift 3中保存更改的视频，我应该使用什么功能？我们使用以下功能来捕获图像的整个屏幕，例如：Video 将更改后的视频保存到Swift 3中的摄像机卷,video,swift3,xcode8,ios10,Video,Swift3,Xcode8,Ios10,为了在Swift 3中保存更改的视频，我应该使用什么功能？我们使用以下功能来捕获图像的整个屏幕，例如： UIGraphicsBeginImageContext(self.view.frame.size) if let ctx = UIGraphicsGetCurrentContext() { self.view.layer.render(in: ctx) let renderedImage = UIGraphicsGetImage
UIGraphicsBeginImageContext(self.view.frame.size)
if let ctx = UIGraphicsGetCurrentContext() {
self.view.layer.render(in: ctx)
let renderedImage = UIGraphicsGetImageFromCurrentImageContext()
UIGraphicsEndImageContext()
那是一项相当复杂的任务 我不希望这个答案比现在更大，所以我将假设两件大事：
- 您已经有了没有图形的视频文件
- 你已经有一幅画了
//Input are video (AVAsset) and image that you already have
func addOverlayTo(asset: AVAsset, overlayImage:UIImage?) {
//this object will be our new video. It describes what will be in it
let mixComposition = AVMutableComposition()
//we tell our composition that there will be video track in it
let videoTrack = mixComposition.addMutableTrack(withMediaType: AVMediaTypeVideo, preferredTrackID: kCMPersistentTrackID_Invalid)
//we add our video file to that track
try! videoTrack.insertTimeRange(CMTimeRangeMake(kCMTimeZero, asset.duration),
of: asset.tracks(withMediaType: AVMediaTypeVideo)[0] ,
at: kCMTimeZero)
//this object tells how to display our video
let mainCompositionInst = AVMutableVideoComposition()
//in iOS videos are always stored in landscape right orientation
//so to orient and size everything properly we have to look at transform property of asset
let size = determineRenderSize(for: asset)
//these steps are necessary only if our video has multiple layers
if overlayImage != nil {
//create all necessary layers
let videoLayer = CALayer()
videoLayer.frame = CGRect(origin: CGPoint(x: 0, y: 0), size: size)
let parentLayer = CALayer()
parentLayer.frame = CGRect(origin: CGPoint(x: 0, y: 0), size: size)
parentLayer.addSublayer(videoLayer)
if overlayImage != nil{
let overlayLayer = CALayer()
overlayLayer.contents = overlayImage?.cgImage
overlayLayer.frame = CGRect(origin: CGPoint(x: 0, y: 0), size: size)
parentLayer.addSublayer(overlayLayer)
}
//layout layers properly
mainCompositionInst.animationTool = AVVideoCompositionCoreAnimationTool(postProcessingAsVideoLayer: videoLayer, in: parentLayer)
}
let mainInstruction = AVMutableVideoCompositionInstruction()
//this object will rotate our video to proper orientation
let layerInstruction = AVMutableVideoCompositionLayerInstruction(assetTrack: videoTrack)
layerInstruction.setTransform(videoTrack.preferredTransform, at: kCMTimeZero)
mainInstruction.layerInstructions = [layerInstruction]
mainCompositionInst.instructions = [mainInstruction]
//now we have to fill all properties of our composition instruction
//their names are quite informative so I won't comment much
mainCompositionInst.renderSize = size
mainCompositionInst.renderScale = 1.0
//assumed standard 30 fps. It's written as 20/600 because videos
//from built in phone camera have default time scale 600
mainCompositionInst.frameDuration = CMTimeMake(20,600)
mainInstruction.timeRange = CMTimeRangeMake(kCMTimeZero, asset.duration)
//now we need to save our new video to phone memory
//object that will do it
let exporter = AVAssetExportSession(asset: mixComposition, presetName: AVAssetExportPresetHighestQuality)!
//create a path where our video will be saved
let documentDirectory = NSSearchPathForDirectoriesInDomains(.documentDirectory, .userDomainMask, true)[0]
let outputPath = documentDirectory + "your_file_name.mp4"
//if there already is a file with this path export will fail
if FileManager.default.fileExists(atPath: outputPath) {
try! FileManager.default.removeItem(atPath: outputPath)
}
exporter.outputURL = URL.init(fileURLWithPath: outputPath)
//again a bunch of parameters that have to be filled. These a pretty standard though
exporter.outputFileType = AVFileTypeQuickTimeMovie
exporter.shouldOptimizeForNetworkUse = true
exporter.videoComposition = mainCompositionInst
exporter.timeRange = CMTimeRangeMake(kCMTimeZero, asset.duration)
exporter.exportAsynchronously { () -> Void in
if exporter.error == nil && exporter.status == .completed{
print("SAVED!")
}
else{
print(exporter.error!
}
}
func determineRenderSize(for asset: AVAsset) -> CGSize {
let videoTrack = asset.tracks(withMediaType: AVMediaTypeVideo)[0]
let size = videoTrack.naturalSize
let txf = videoTrack.preferredTransform
print("transform is ", txf)
if (size.height == txf.tx && txf.ty == 0){
return CGSize(width: size.height, height: size.width) //portrait
}
else if (txf.tx == size.width && txf.ty == size.height){
return size //landscape left
}
else if (txf.tx == 0 && txf.ty == size.width){
return CGSize(width: size.height, height: size.width) //upside down
}
else{
return size //landscape right
}
}