问题
I am trying to useAVVideoComposition to add some text on top of a video and save the video.
This is the code I use:
I Create an AVMutableComposition and AVVideoComposition
var mutableComp = AVMutableComposition()
var mutableVidComp = AVMutableVideoComposition()
var compositionSize : CGSize?
func configureAsset(){
let options = [AVURLAssetPreferPreciseDurationAndTimingKey : "true"]
let videoAsset = AVURLAsset(url: Bundle.main.url(forResource: "Car", withExtension: "mp4")! , options : options)
let videoAssetSourceTrack = videoAsset.tracks(withMediaType: AVMediaTypeVideo).first! as AVAssetTrack
compositionSize = videoAssetSourceTrack.naturalSize
let mutableVidTrack = mutableComp.addMutableTrack(withMediaType: AVMediaTypeVideo, preferredTrackID: kCMPersistentTrackID_Invalid)
let trackRange = CMTimeRangeMake(kCMTimeZero, videoAsset.duration)
do {
try mutableVidTrack.insertTimeRange( trackRange, of: videoAssetSourceTrack, at: kCMTimeZero)
mutableVidTrack.preferredTransform = videoAssetSourceTrack.preferredTransform
}catch { print(error) }
snapshot = mutableComp
mutableVidComp = AVMutableVideoComposition(propertiesOf: videoAsset)
}
II Setup the layers
func applyVideoEffectsToComposition() {
// 1 - Set up the text layer
let subTitle1Text = CATextLayer()
subTitle1Text.font = "Helvetica-Bold" as CFTypeRef
subTitle1Text.frame = CGRect(x: self.view.frame.midX - 60 , y: self.view.frame.midY - 50, width: 120, height: 100)
subTitle1Text.string = "Bench"
subTitle1Text.foregroundColor = UIColor.black.cgColor
subTitle1Text.alignmentMode = kCAAlignmentCenter
// 2 - The usual overlay
let overlayLayer = CALayer()
overlayLayer.addSublayer(subTitle1Text)
overlayLayer.frame = CGRect(x: 0, y: 0, width: compositionSize!.width, height: compositionSize!.height)
overlayLayer.masksToBounds = true
// 3 - set up the parent layer
let parentLayer = CALayer()
let videoLayer = CALayer()
parentLayer.frame = CGRect(x: 0, y: 0, width: compositionSize!.width, height: compositionSize!.height)
videoLayer.frame = CGRect(x: 0, y: 0, width: compositionSize!.width, height: compositionSize!.height)
parentLayer.addSublayer(videoLayer)
parentLayer.addSublayer(overlayLayer)
mutableVidComp.animationTool = AVVideoCompositionCoreAnimationTool(postProcessingAsVideoLayer: videoLayer, in: parentLayer)
}
III . Save video with AVMutbaleVideoComposition
func saveAsset (){
func deleteFile(_ filePath:URL) {
guard FileManager.default.fileExists(atPath: filePath.path) else { return }
do {
try FileManager.default.removeItem(atPath: filePath.path) }
catch {fatalError("Unable to delete file: \(error) : \(#function).")} }
let documentsDirectory = FileManager.default.urls(for: .documentDirectory, in: .userDomainMask)[0] as URL
let filePath = documentsDirectory.appendingPathComponent("rendered-audio.mp4")
deleteFile(filePath)
if let exportSession = AVAssetExportSession(asset: mutableComp , presetName: AVAssetExportPresetHighestQuality){
exportSession.videoComposition = mutableVidComp
// exportSession.canPerformMultiplePassesOverSourceMediaData = true
exportSession.outputURL = filePath
exportSession.shouldOptimizeForNetworkUse = true
exportSession.timeRange = CMTimeRangeMake(kCMTimeZero, mutableComp.duration)
exportSession.outputFileType = AVFileTypeQuickTimeMovie
exportSession.exportAsynchronously {
print("finished: \(filePath) : \(exportSession.status.rawValue) ")
if exportSession.status.rawValue == 4 {
print("Export failed -> Reason: \(exportSession.error!.localizedDescription))")
print(exportSession.error!)
}
}
}
}
Then I run all three methods in the viewDidLoad method for a quick test. The problem is that when I run the app ,the result of the export is the original video without the title on it.
What am I missing here?
UPDATE
I notice that adding a subTitle1Text.backgroundColor property in
part II of the code makes a colored CGRect corresponding to subTitle1Text.frame appear on top of the video when exported.
(See Image)
When this code is modified for playback using AVSynchronizedLayer the desired layer can be seen on top of the video with text on it.
So perhaps this is a bug in AVFoundation itself.
I suppose I am only left with the option of using a customVideoCompositorClass. The problem with that is that it takes a lot of time to render the video . Here is an example that uses AVVideoCompositing
回答1:
Here is full working code which I used in my project. It will show CATextLayer at bottom (0,0). And in export session finish it will replace new path in player item. I used one model from Objective C code to get orientation. Please do testing in device. AVPLayer will not show text layer properly in simulator.
let composition = AVMutableComposition.init()
let videoComposition = AVMutableVideoComposition()
videoComposition.frameDuration = CMTimeMake(1, 30)
videoComposition.renderScale = 1.0
let compositionCommentaryTrack: AVMutableCompositionTrack? = composition.addMutableTrack(withMediaType: AVMediaTypeAudio, preferredTrackID: kCMPersistentTrackID_Invalid)
let compositionVideoTrack: AVMutableCompositionTrack? = composition.addMutableTrack(withMediaType: AVMediaTypeVideo, preferredTrackID: kCMPersistentTrackID_Invalid)
let clipVideoTrack:AVAssetTrack = self.currentAsset.tracks(withMediaType: AVMediaTypeVideo)[0]
let audioTrack: AVAssetTrack? = self.currentAsset.tracks(withMediaType: AVMediaTypeAudio)[0]
try? compositionCommentaryTrack?.insertTimeRange(CMTimeRangeMake(kCMTimeZero, self.currentAsset.duration), of: audioTrack!, at: kCMTimeZero)
try? compositionVideoTrack?.insertTimeRange(CMTimeRangeMake(kCMTimeZero, self.currentAsset.duration), of: clipVideoTrack, at: kCMTimeZero)
let orientation = VideoModel.videoOrientation(self.currentAsset)
var isPortrait = false
switch orientation {
case .landscapeRight:
isPortrait = false
case .landscapeLeft:
isPortrait = false
case .portrait:
isPortrait = true
case .portraitUpsideDown:
isPortrait = true
}
var naturalSize = clipVideoTrack.naturalSize
if isPortrait
{
naturalSize = CGSize.init(width: naturalSize.height, height: naturalSize.width)
}
videoComposition.renderSize = naturalSize
let scale = CGFloat(1.0)
var transform = CGAffineTransform.init(scaleX: CGFloat(scale), y: CGFloat(scale))
switch orientation {
case .landscapeRight: break
// isPortrait = false
case .landscapeLeft:
transform = transform.translatedBy(x: naturalSize.width, y: naturalSize.height)
transform = transform.rotated(by: .pi)
case .portrait:
transform = transform.translatedBy(x: naturalSize.width, y: 0)
transform = transform.rotated(by: CGFloat(M_PI_2))
case .portraitUpsideDown:break
}
let frontLayerInstruction = AVMutableVideoCompositionLayerInstruction(assetTrack: compositionVideoTrack!)
frontLayerInstruction.setTransform(transform, at: kCMTimeZero)
let MainInstruction = AVMutableVideoCompositionInstruction()
MainInstruction.timeRange = CMTimeRangeMake(kCMTimeZero, composition.duration)
MainInstruction.layerInstructions = [frontLayerInstruction]
videoComposition.instructions = [MainInstruction]
let parentLayer = CALayer.init()
parentLayer.frame = CGRect.init(x: 0, y: 0, width: naturalSize.width, height: naturalSize.height)
let videoLayer = CALayer.init()
videoLayer.frame = parentLayer.frame
let layer = CATextLayer()
layer.string = "HELLO ALL"
layer.foregroundColor = UIColor.white.cgColor
layer.backgroundColor = UIColor.orange.cgColor
layer.fontSize = 32
layer.frame = CGRect.init(x: 0, y: 0, width: 300, height: 100)
var rct = layer.frame;
let widthScale = self.playerView.frame.size.width/naturalSize.width
rct.size.width /= widthScale
rct.size.height /= widthScale
rct.origin.x /= widthScale
rct.origin.y /= widthScale
parentLayer.addSublayer(videoLayer)
parentLayer.addSublayer(layer)
videoComposition.animationTool = AVVideoCompositionCoreAnimationTool.init(postProcessingAsVideoLayer: videoLayer, in: parentLayer)
let documentsPath = NSSearchPathForDirectoriesInDomains(.documentDirectory, .userDomainMask, true)[0]
let videoPath = documentsPath+"/cropEditVideo.mov"
let fileManager = FileManager.default
if fileManager.fileExists(atPath: videoPath)
{
try! fileManager.removeItem(atPath: videoPath)
}
print("video path \(videoPath)")
var exportSession = AVAssetExportSession.init(asset: composition, presetName: AVAssetExportPresetHighestQuality)
exportSession?.videoComposition = videoComposition
exportSession?.outputFileType = AVFileTypeQuickTimeMovie
exportSession?.outputURL = URL.init(fileURLWithPath: videoPath)
exportSession?.videoComposition = videoComposition
var exportProgress: Float = 0
let queue = DispatchQueue(label: "Export Progress Queue")
queue.async(execute: {() -> Void in
while exportSession != nil {
// int prevProgress = exportProgress;
exportProgress = (exportSession?.progress)!
print("current progress == \(exportProgress)")
sleep(1)
}
})
exportSession?.exportAsynchronously(completionHandler: {
if exportSession?.status == AVAssetExportSessionStatus.failed
{
print("Failed \(exportSession?.error)")
}else if exportSession?.status == AVAssetExportSessionStatus.completed
{
exportSession = nil
let asset = AVAsset.init(url: URL.init(fileURLWithPath: videoPath))
DispatchQueue.main.async {
let item = AVPlayerItem.init(asset: asset)
self.player.replaceCurrentItem(with: item)
let assetDuration = CMTimeGetSeconds(composition.duration)
self.progressSlider.maximumValue = Float(assetDuration)
self.syncLayer.removeFromSuperlayer()
self.lblIntro.isHidden = true
self.player.play()
// let url = URL.init(fileURLWithPath: videoPath)
// let activityVC = UIActivityViewController(activityItems: [url], applicationActivities: [])
// self.present(activityVC, animated: true, completion: nil)
}
}
})
Below is code of My VideoModel class
-(AVCaptureVideoOrientation)videoOrientation:(AVAsset *)asset
{
AVCaptureVideoOrientation result = 0;
NSArray *tracks = [asset tracksWithMediaType:AVMediaTypeVideo];
if([tracks count] > 0) {
AVAssetTrack *videoTrack = [tracks objectAtIndex:0];
CGAffineTransform t = videoTrack.preferredTransform;
// Portrait
if(t.a == 0 && t.b == 1.0 && t.c == -1.0 && t.d == 0)
{
result = AVCaptureVideoOrientationPortrait;
}
// PortraitUpsideDown
if(t.a == 0 && t.b == -1.0 && t.c == 1.0 && t.d == 0) {
result = AVCaptureVideoOrientationPortraitUpsideDown;
}
// LandscapeRight
if(t.a == 1.0 && t.b == 0 && t.c == 0 && t.d == 1.0)
{
result = AVCaptureVideoOrientationLandscapeRight;
}
// LandscapeLeft
if(t.a == -1.0 && t.b == 0 && t.c == 0 && t.d == -1.0)
{
result = AVCaptureVideoOrientationLandscapeLeft;
}
}
return result;
}
Let me know if you need any more help in this.
来源：https://stackoverflow.com/questions/45198189/swift-3-how-to-export-video-with-text-using-avvideocomposition