Swift: Adding Audio to AVMutableComposition - ios

Question

I'm using the code in the answer to the question posted here (added below):
Swift 3: How to add watermark on video ? AVVideoCompositionCoreAnimationTool iOS 10 issue
The code strips the video track from a recorded video and adds a watermark. The code doesn't merge the audio track so the output is the watermarked video with no audio.
How can I merge the audio back into the watermarked video?
The code:
import UIKit
import AssetsLibrary
import AVFoundation
import Photos
enum QUWatermarkPosition {
case TopLeft
case TopRight
case BottomLeft
case BottomRight
case Default
}
class QUWatermarkManager: NSObject {
func watermark(video videoAsset:AVAsset, watermarkText text : String, saveToLibrary flag : Bool, watermarkPosition position : QUWatermarkPosition, completion : ((_ status : AVAssetExportSessionStatus?, _ session: AVAssetExportSession?, _ outputURL : URL?) -> ())?) {
self.watermark(video: videoAsset, watermarkText: text, imageName: nil, saveToLibrary: flag, watermarkPosition: position) { (status, session, outputURL) -> () in
completion!(status, session, outputURL)
}
}
func watermark(video videoAsset:AVAsset, imageName name : String, saveToLibrary flag : Bool, watermarkPosition position : QUWatermarkPosition, completion : ((_ status : AVAssetExportSessionStatus?, _ session: AVAssetExportSession?, _ outputURL : URL?) -> ())?) {
self.watermark(video: videoAsset, watermarkText: nil, imageName: name, saveToLibrary: flag, watermarkPosition: position) { (status, session, outputURL) -> () in
completion!(status, session, outputURL)
}
}
private func watermark(video videoAsset:AVAsset, watermarkText text : String!, imageName name : String!, saveToLibrary flag : Bool, watermarkPosition position : QUWatermarkPosition, completion : ((_ status : AVAssetExportSessionStatus?, _ session: AVAssetExportSession?, _ outputURL : URL?) -> ())?) {
DispatchQueue.global(qos: DispatchQoS.QoSClass.default).async {
let mixComposition = AVMutableComposition()
let compositionVideoTrack = mixComposition.addMutableTrack(withMediaType: AVMediaTypeVideo, preferredTrackID: Int32(kCMPersistentTrackID_Invalid))
let clipVideoTrack = videoAsset.tracks(withMediaType: AVMediaTypeVideo)[0]
do {
try compositionVideoTrack.insertTimeRange(CMTimeRangeMake(kCMTimeZero, videoAsset.duration), of: clipVideoTrack, at: kCMTimeZero)
}
catch {
print(error.localizedDescription)
}
let videoSize = clipVideoTrack.naturalSize
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)
if text != nil {
let titleLayer = CATextLayer()
titleLayer.backgroundColor = UIColor.red.cgColor
titleLayer.string = text
titleLayer.font = "Helvetica" as CFTypeRef
titleLayer.fontSize = 15
titleLayer.alignmentMode = kCAAlignmentCenter
titleLayer.bounds = CGRect(x: 0, y: 0, width: videoSize.width, height: videoSize.height)
parentLayer.addSublayer(titleLayer)
} else if name != nil {
let watermarkImage = UIImage(named: name)
let imageLayer = CALayer()
imageLayer.contents = watermarkImage?.cgImage
var xPosition : CGFloat = 0.0
var yPosition : CGFloat = 0.0
let imageSize : CGFloat = 57.0
switch (position) {
case .TopLeft:
xPosition = 0
yPosition = 0
break
case .TopRight:
xPosition = videoSize.width - imageSize
yPosition = 0
break
case .BottomLeft:
xPosition = 0
yPosition = videoSize.height - imageSize
break
case .BottomRight, .Default:
xPosition = videoSize.width - imageSize
yPosition = videoSize.height - imageSize
break
}
imageLayer.frame = CGRect(x: xPosition, y: yPosition, width: imageSize, height: imageSize)
imageLayer.opacity = 0.65
parentLayer.addSublayer(imageLayer)
}
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)
_ = mixComposition.tracks(withMediaType: AVMediaTypeVideo)[0] as AVAssetTrack
let layerInstruction = self.videoCompositionInstructionForTrack(track: compositionVideoTrack, asset: videoAsset)
instruction.layerInstructions = [layerInstruction]
videoComp.instructions = [instruction]
let documentDirectory = NSSearchPathForDirectoriesInDomains(.documentDirectory, .userDomainMask, true)[0]
let dateFormatter = DateFormatter()
dateFormatter.dateStyle = .long
dateFormatter.timeStyle = .short
let date = dateFormatter.string(from: Date())
let url = URL(fileURLWithPath: documentDirectory).appendingPathComponent("watermarkVideo-\(date).mov")
let exporter = AVAssetExportSession(asset: mixComposition, presetName: AVAssetExportPresetHighestQuality)
exporter?.outputURL = url
exporter?.outputFileType = AVFileTypeQuickTimeMovie
exporter?.shouldOptimizeForNetworkUse = true
exporter?.videoComposition = videoComp
exporter?.exportAsynchronously() {
DispatchQueue.main.async {
if exporter?.status == AVAssetExportSessionStatus.completed {
let outputURL = exporter?.outputURL
if flag {
// Save to library
// let library = ALAssetsLibrary()
if UIVideoAtPathIsCompatibleWithSavedPhotosAlbum(outputURL!.path) {
PHPhotoLibrary.shared().performChanges({
PHAssetChangeRequest.creationRequestForAssetFromVideo(atFileURL: outputURL!)
}) { saved, error in
if saved {
completion!(AVAssetExportSessionStatus.completed, exporter, outputURL)
}
}
}
// if library.videoAtPathIs(compatibleWithSavedPhotosAlbum: outputURL) {
// library.writeVideoAtPathToSavedPhotosAlbum(outputURL,
// completionBlock: { (assetURL:NSURL!, error:NSError!) -> Void in
//
// completion!(AVAssetExportSessionStatus.Completed, exporter, outputURL)
// })
// }
} else {
completion!(AVAssetExportSessionStatus.completed, exporter, outputURL)
}
} else {
// Error
completion!(exporter?.status, exporter, nil)
}
}
}
}
}
private func orientationFromTransform(transform: CGAffineTransform) -> (orientation: UIImageOrientation, isPortrait: Bool) {
var assetOrientation = UIImageOrientation.up
var isPortrait = false
if transform.a == 0 && transform.b == 1.0 && transform.c == -1.0 && transform.d == 0 {
assetOrientation = .right
isPortrait = true
} else if transform.a == 0 && transform.b == -1.0 && transform.c == 1.0 && transform.d == 0 {
assetOrientation = .left
isPortrait = true
} else if transform.a == 1.0 && transform.b == 0 && transform.c == 0 && transform.d == 1.0 {
assetOrientation = .up
} else if transform.a == -1.0 && transform.b == 0 && transform.c == 0 && transform.d == -1.0 {
assetOrientation = .down
}
return (assetOrientation, isPortrait)
}
private func videoCompositionInstructionForTrack(track: AVCompositionTrack, asset: AVAsset) -> AVMutableVideoCompositionLayerInstruction {
let instruction = AVMutableVideoCompositionLayerInstruction(assetTrack: track)
let assetTrack = asset.tracks(withMediaType: AVMediaTypeVideo)[0]
let transform = assetTrack.preferredTransform
let assetInfo = orientationFromTransform(transform: transform)
var scaleToFitRatio = UIScreen.main.bounds.width / assetTrack.naturalSize.width
if assetInfo.isPortrait {
scaleToFitRatio = UIScreen.main.bounds.width / assetTrack.naturalSize.height
let scaleFactor = CGAffineTransform(scaleX: scaleToFitRatio, y: scaleToFitRatio)
instruction.setTransform(assetTrack.preferredTransform.concatenating(scaleFactor),
at: kCMTimeZero)
} else {
let scaleFactor = CGAffineTransform(scaleX: scaleToFitRatio, y: scaleToFitRatio)
var concat = assetTrack.preferredTransform.concatenating(scaleFactor).concatenating(CGAffineTransform(translationX: 0, y: UIScreen.main.bounds.width / 2))
if assetInfo.orientation == .down {
let fixUpsideDown = CGAffineTransform(rotationAngle: CGFloat(Double.pi))
let windowBounds = UIScreen.main.bounds
let yFix = assetTrack.naturalSize.height + windowBounds.height
let centerFix = CGAffineTransform(translationX: assetTrack.naturalSize.width, y: yFix)
concat = fixUpsideDown.concatenating(centerFix).concatenating(scaleFactor)
}
instruction.setTransform(concat, at: kCMTimeZero)
}
return instruction
}
}

Answer 1

Adding the following code achieved my goal:
let compositionAudioVideo: AVMutableCompositionTrack = mixComposition.addMutableTrack(withMediaType: AVMediaType.audio, preferredTrackID: CMPersistentTrackID())!
let audioMix: AVMutableAudioMix = AVMutableAudioMix()
var audioMixParam: [AVMutableAudioMixInputParameters] = []
let assetVideoTrack: AVAssetTrack = videoAsset.tracks(withMediaType: AVMediaType.audio)[0]
let videoParam: AVMutableAudioMixInputParameters = AVMutableAudioMixInputParameters(track: assetVideoTrack)
videoParam.trackID = compositionAudioVideo.trackID
audioMixParam.append(videoParam)
do {
try compositionAudioVideo.insertTimeRange(CMTimeRangeMake(kCMTimeZero, videoAsset.duration), of: assetVideoTrack, at: kCMTimeZero)
} catch _ {
assertionFailure()
}
audioMix.inputParameters = audioMixParam