在视频上添加标签iOS

Question

我试图实现的目标是在视频上添加自定义UILabel，以使其显示为UILabel的各种属性，然后获得新视频。标签可以具有不同的颜色，变化的字体大小和阴影等。因此使用字符串代替UILabel将不会有用。同样，由于UILabel可以被平移，所以使用精确标签更为重要，因为根据视频它会有一个框架。

考虑这一点对于我所试图实现：

Answer 1

这些方法帮助我实现上述任务： 让我知道，如果你面对的问题。谢谢！

func applyVideoEffects(to composition: AVMutableVideoComposition, size: CGSize, currentLabel: UILabel) { 

    let overlayLayer = CALayer() 
    var overlayImage: UIImage? = nil 
    overlayImage = UIImage.createTransparentImageFrom(label: currentLabel, imageSize: CGSize(width: UIScreen.main.bounds.width, height: UIScreen.main.bounds.width)) 
    overlayLayer.contents = overlayImage?.cgImage 
    overlayLayer.frame = CGRect(x: 0, y: 0, width: size.width, height: size.height) 
    overlayLayer.masksToBounds = true 


    let parentLayer = CALayer() 
    let videoLayer = CALayer() 
    parentLayer.frame = CGRect(x: 0, y: 0, width: size.width, height: size.height) 
    videoLayer.frame = CGRect(x: 0, y: 0, width: size.width, height: size.height) 
    parentLayer.addSublayer(videoLayer) 
    parentLayer.addSublayer(overlayLayer) 
    // 3 - apply magic 
    composition.animationTool = AVVideoCompositionCoreAnimationTool(postProcessingAsVideoLayer: videoLayer, in: parentLayer) 
} 

func videoOutput(videoAsset: AVAsset, label: UILabel) { 

    // Create AVMutableComposition object. This object will hold your AVMutableCompositionTrack instances. 
    let mixComposition = AVMutableComposition() 

    // Video track 
    let videoTrack = mixComposition.addMutableTrack(withMediaType: AVMediaTypeVideo, preferredTrackID: kCMPersistentTrackID_Invalid) 
    do { 
     try videoTrack.insertTimeRange(CMTimeRange(start: kCMTimeZero, duration: videoAsset.duration), of: videoAsset.tracks(withMediaType: AVMediaTypeVideo)[0], at: kCMTimeZero) 
    } catch { 
     print("Error selecting video track !!") 
    } 

    // Create AVMutableVideoCompositionInstruction 

    let mainInstruction = AVMutableVideoCompositionInstruction() 
    mainInstruction.timeRange = CMTimeRange(start: kCMTimeZero, duration: videoAsset.duration) 

    // Create an AvmutableVideoCompositionLayerInstruction for the video track and fix orientation 

    let videoLayerInstruction = AVMutableVideoCompositionLayerInstruction.init(assetTrack: videoTrack) 
    let videoAssetTrack = videoAsset.tracks(withMediaType: AVMediaTypeVideo)[0] 
    var videoAssetOrientation = UIImageOrientation.up 
    var isVideoAssetPortrait = false 
    let videoTransform = videoAssetTrack.preferredTransform 

    if videoTransform.a == 0 && videoTransform.b == 1.0 && videoTransform.c == -1.0 && videoTransform.d == 0 { 
     videoAssetOrientation = .right 
     isVideoAssetPortrait = true 
    } 
    if videoTransform.a == 0 && videoTransform.b == -1.0 && videoTransform.c == 1.0 && videoTransform.d == 0 { 
     videoAssetOrientation = .left 
     isVideoAssetPortrait = true 
    } 
    if videoTransform.a == 1.0 && videoTransform.b == 0 && videoTransform.c == 0 && videoTransform.d == 1.0 { 
     videoAssetOrientation = .up 
    } 
    if videoTransform.a == -1.0 && videoTransform.b == 0 && videoTransform.c == 0 && videoTransform.d == -1.0 { 
     videoAssetOrientation = .down 
    } 

    videoLayerInstruction.setTransform(videoAssetTrack.preferredTransform, at: kCMTimeZero) 
    videoLayerInstruction.setOpacity(0.0, at: videoAsset.duration) 

    //Add instructions 

    mainInstruction.layerInstructions = [videoLayerInstruction] 
    let mainCompositionInst = AVMutableVideoComposition() 
    let naturalSize : CGSize! 
    if isVideoAssetPortrait { 
     naturalSize = CGSize(width: videoAssetTrack.naturalSize.height, height: videoAssetTrack.naturalSize.width) 
    } else { 
     naturalSize = videoAssetTrack.naturalSize 
    } 

    let renderWidth = naturalSize.width 
    let renderHeight = naturalSize.height 

    mainCompositionInst.renderSize = CGSize(width: renderWidth, height: renderHeight) 
    mainCompositionInst.instructions = [mainInstruction] 
    mainCompositionInst.frameDuration = CMTime(value: 1, timescale: 30) 

    self.applyVideoEffects(to: mainCompositionInst, size: naturalSize, currentLabel: label) 

    // Get Path 
    let documentsURL = FileManager.default.urls(for: .documentDirectory, in: .userDomainMask).first 
    let outputPath = documentsURL?.appendingPathComponent("newVideoWithLabel.mp4") 
    if FileManager.default.fileExists(atPath: (outputPath?.path)!) { 
     do { 
      try FileManager.default.removeItem(atPath: (outputPath?.path)!) 
     } 
     catch { 
      print ("Error deleting file") 
     } 
    } 
    // Create exporter 

    let exporter = AVAssetExportSession.init(asset: mixComposition, presetName: AVAssetExportPresetHighestQuality) 
    exporter?.outputURL = outputPath 
    exporter?.outputFileType = AVFileTypeQuickTimeMovie 
    exporter?.shouldOptimizeForNetworkUse = true 
    exporter?.videoComposition = mainCompositionInst 
    exporter?.exportAsynchronously(completionHandler: { 
     self.exportDidFinish(session: exporter!) 
    }) 
} 

func exportDidFinish(session: AVAssetExportSession) { 
    if session.status == .completed { 
     let outputURL: URL? = session.outputURL 
     PHPhotoLibrary.shared().performChanges({ 
      PHAssetChangeRequest.creationRequestForAssetFromVideo(atFileURL: outputURL!) 
     }) { saved, error in 
      if saved { 
       let fetchOptions = PHFetchOptions() 
       fetchOptions.sortDescriptors = [NSSortDescriptor(key: "creationDate", ascending: true)] 
       let fetchResult = PHAsset.fetchAssets(with: .video, options: fetchOptions).lastObject 
       PHImageManager().requestAVAsset(forVideo: fetchResult!, options: nil, resultHandler: { (avurlAsset, audioMix, dict) in 
        let newObj = avurlAsset as! AVURLAsset 
        print(newObj.url) 
        DispatchQueue.main.async(execute: { 
         print(newObj.url.absoluteString) 
        }) 
       }) 
       print (fetchResult!) 
      } 
     } 
    } 
} 

import Foundation 
import UIKit 

extension UIImage { 
    class func createTransparentImageFrom(label: UILabel, imageSize: CGSize) -> UIImage { 
     UIGraphicsBeginImageContextWithOptions(imageSize, false, 2.0) 
     let currentView = UIView.init(frame: CGRect(x: 0, y: 0, width: imageSize.width, height: imageSize.height)) 
     currentView.backgroundColor = UIColor.clear 
    currentView.addSubview(label) 

     currentView.layer.render(in: UIGraphicsGetCurrentContext()!) 
     let img = UIGraphicsGetImageFromCurrentImageContext() 
     UIGraphicsEndImageContext() 
     return img! 
    } 
}