我在合成中使用了3个视频。我似乎无法弄清楚为什么第二个人在将它们合并在一起后会变成黑色。调试时它有正确的时间和值，所以我知道它在那里。这是我的代码：
import UIKit
import AVFoundation
import MobileCoreServices
import CoreMedia
import AssetsLibrary
import MediaPlayer
import Photos
class MergeViewController: UIViewController, UINavigationControllerDelegate, UIImagePickerControllerDelegate, MPMediaPickerControllerDelegate {
let clipPicker = UIImagePickerController()
let audioPicker = MPMediaPickerController()
var isSelectingAsset: Int!
// video clip 1
var firstAsset: AVAsset!
// video clip 2
var secondAsset: AVAsset!
// video clip 3
var thirdAsset: AVAsset!
// sound track
var audioAsset: AVAsset!
// activity view indicator
override func viewDidLoad() {
super.viewDidLoad()
clipPicker.delegate = self
clipPicker.sourceType = UIImagePickerControllerSourceType.PhotoLibrary
clipPicker.mediaTypes = [kUTTypeMovie]
audioPicker.delegate = self
audioPicker.prompt = "Select Audio"
}
@IBAction func loadAsset1(sender: AnyObject) {
if UIImagePickerController.isSourceTypeAvailable(UIImagePickerControllerSourceType.PhotoLibrary) {
isSelectingAsset = 1
self.presentViewController(clipPicker, animated: true, completion: nil)
}
}
@IBAction func loadAsset2(sender: AnyObject) {
if UIImagePickerController.isSourceTypeAvailable(UIImagePickerControllerSourceType.PhotoLibrary) {
isSelectingAsset = 2
self.presentViewController(clipPicker, animated: true, completion: nil)
}
}
@IBAction func loadAsset3(sender: AnyObject) {
if UIImagePickerController.isSourceTypeAvailable(UIImagePickerControllerSourceType.PhotoLibrary) {
isSelectingAsset = 3
self.presentViewController(clipPicker, animated: true, completion: nil)
}
}
@IBAction func loadAudio(sender: AnyObject) {
self.presentViewController(audioPicker, animated: true, completion: nil)
}
@IBAction func mergeMedia(sender: AnyObject) {
if firstAsset != nil && secondAsset != nil && thirdAsset != nil {
// set up container to hold media tracks.
var mixComposition = AVMutableComposition()
// track times
let track1to2Time = CMTimeAdd(firstAsset.duration, secondAsset.duration)
let totalTime = CMTimeAdd(track1to2Time, thirdAsset.duration)
// create separate video tracks for individual adjustments before merge
var firstTrack = mixComposition.addMutableTrackWithMediaType(AVMediaTypeVideo,
preferredTrackID: Int32(kCMPersistentTrackID_Invalid))
firstTrack.insertTimeRange(CMTimeRangeMake(kCMTimeZero, firstAsset.duration),
ofTrack: firstAsset.tracksWithMediaType(AVMediaTypeVideo)[0] as! AVAssetTrack,
atTime: kCMTimeZero,
error: nil)
var secondTrack = mixComposition.addMutableTrackWithMediaType(AVMediaTypeVideo,
preferredTrackID: Int32(kCMPersistentTrackID_Invalid))
secondTrack.insertTimeRange(CMTimeRangeMake(kCMTimeZero, secondAsset.duration),
ofTrack: secondAsset.tracksWithMediaType(AVMediaTypeVideo)[0] as! AVAssetTrack,
atTime: firstAsset.duration,
error: nil)
var thirdTrack = mixComposition.addMutableTrackWithMediaType(AVMediaTypeVideo,
preferredTrackID: Int32(kCMPersistentTrackID_Invalid))
thirdTrack.insertTimeRange(CMTimeRangeMake(kCMTimeZero, thirdAsset.duration),
ofTrack: thirdAsset.tracksWithMediaType(AVMediaTypeVideo)[0] as! AVAssetTrack,
atTime: track1to2Time,
error: nil)
// Set up an overall instructions array
var mainInstruction = AVMutableVideoCompositionInstruction()
mainInstruction.timeRange = CMTimeRangeMake(kCMTimeZero, totalTime)
// Create seperate instructions for each track with helper method to correct orientation.
let firstInstruction = videoCompositionInstructionForTrack(firstTrack, asset: firstAsset)
// Make sure each track becomes transparent at end for the next one to play.
firstInstruction.setOpacity(0.0, atTime: firstAsset.duration)
let secondInstruction = videoCompositionInstructionForTrack(secondTrack, asset: secondAsset)
secondInstruction.setOpacity(0.0, atTime: secondAsset.duration)
let thirdInstruction = videoCompositionInstructionForTrack(thirdTrack, asset: thirdAsset)
// Add individual instructions to main for execution.
mainInstruction.layerInstructions = [firstInstruction, secondInstruction, thirdInstruction]
let mainComposition = AVMutableVideoComposition()
// Add instruction composition to main composition and set frame rate to 30 per second.
mainComposition.instructions = [mainInstruction]
mainComposition.frameDuration = CMTimeMake(1, 30)
mainComposition.renderSize = CGSize(
width: UIScreen.mainScreen().bounds.width,
height: UIScreen.mainScreen().bounds.height)
// get audio
if audioAsset != nil {
let audioTrack: AVMutableCompositionTrack = mixComposition.addMutableTrackWithMediaType(AVMediaTypeAudio, preferredTrackID: 0)
audioTrack.insertTimeRange(CMTimeRangeMake(kCMTimeZero, totalTime), ofTrack: audioAsset.tracksWithMediaType(AVMediaTypeAudio)[0] as! AVAssetTrack,
atTime: kCMTimeZero,
error: nil)
}
// get path
var paths: NSArray = NSSearchPathForDirectoriesInDomains(NSSearchPathDirectory.DocumentDirectory, NSSearchPathDomainMask.UserDomainMask, true)
let documentsDirectory: String = paths[0] as! String
let id = String(arc4random() % 1000)
let myPathDocs: String = documentsDirectory.stringByAppendingPathComponent("mergeVideo-\(id).mov")
let url = NSURL(fileURLWithPath: myPathDocs)
// make exporter
var exporter = AVAssetExportSession(
asset: mixComposition,
presetName: AVAssetExportPresetHighestQuality)
exporter.outputURL = url
exporter.outputFileType = AVFileTypeQuickTimeMovie
exporter.shouldOptimizeForNetworkUse = true
exporter.videoComposition = mainComposition
exporter.exportAsynchronouslyWithCompletionHandler() {
dispatch_async(dispatch_get_main_queue(), { () -> Void in
self.exportDidFinish(exporter)
})
}
}
}
// MARK: Image Picker Methods
func imagePickerController(picker: UIImagePickerController, didFinishPickingMediaWithInfo info: [NSObject : AnyObject]) {
// Get the media type
let imageType: String = info[UIImagePickerControllerMediaType] as! String
let url: NSURL = info[UIImagePickerControllerMediaURL] as! NSURL
println(imageType)
// Place movie in queue.
if isSelectingAsset == 1 {
println("Success loading 1")
firstAsset = AVAsset.assetWithURL(url) as! AVAsset
} else if isSelectingAsset == 2 {
println("Success loading 2")
secondAsset = AVAsset.assetWithURL(url) as! AVAsset
} else if isSelectingAsset == 3 {
println("Success loading 3")
thirdAsset = AVAsset.assetWithURL(url) as! AVAsset
}
// Dismiss movie selection.
self.dismissViewControllerAnimated(true, completion: nil)
}
func mediaPicker(mediaPicker: MPMediaPickerController!, didPickMediaItems mediaItemCollection: MPMediaItemCollection!) {
let song: NSArray = [mediaItemCollection.items]
if song.count > 0 {
var selectedSong: MPMediaItem! = song[0][0] as! MPMediaItem
let url: NSURL = selectedSong.valueForProperty(MPMediaItemPropertyAssetURL) as! NSURL
audioAsset = AVAsset.assetWithURL(url) as! AVAsset
println("Audio loaded")
}
self.dismissViewControllerAnimated(true, completion: nil)
}
func mediaPickerDidCancel(mediaPicker: MPMediaPickerController!) {
self.dismissViewControllerAnimated(true, completion: nil)
}
// MARK: Merge Helper Methods
func exportDidFinish(session:AVAssetExportSession) {
assert(session.status == AVAssetExportSessionStatus.Completed, "Session status not completed")
if session.status == AVAssetExportSessionStatus.Completed {
let outputURL: NSURL = session.outputURL
let library = ALAssetsLibrary()
if library.videoAtPathIsCompatibleWithSavedPhotosAlbum(outputURL) {
library.writeVideoAtPathToSavedPhotosAlbum(outputURL, completionBlock: { (assetURL: NSURL!, error: NSError!) -> Void in
dispatch_async(dispatch_get_main_queue(), { () -> Void in
if (error != nil) {
let alert = UIAlertView(title: "Error", message: "Failed to save video.", delegate: nil, cancelButtonTitle: "OK")
alert.show()
} else {
let alert = UIAlertView(title: "Success", message: "Video saved.", delegate: nil, cancelButtonTitle: "OK")
alert.show()
}
})
})
}
}
audioAsset = nil
firstAsset = nil
secondAsset = nil
thirdAsset = nil
}
// Identify the correct orientation for the output video based on the input.
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)
}
func videoCompositionInstructionForTrack(track: AVCompositionTrack, asset: AVAsset) -> AVMutableVideoCompositionLayerInstruction {
// get the asset tracks current orientation
let instruction = AVMutableVideoCompositionLayerInstruction(assetTrack: track)
let assetTrack = asset.tracksWithMediaType(AVMediaTypeVideo)[0] as! AVAssetTrack
var transform = assetTrack.preferredTransform
// identify the needed orientation
let assetInfo = orientationFromTransform(transform)
// find the size needed to fit the track in the screen for landscape
var scaleToFitRatio = UIScreen.mainScreen().bounds.width / assetTrack.naturalSize.width
// if it is portrait, get the size to fit the track in the screen and return instruction to scale.
if assetInfo.isPortrait {
scaleToFitRatio = UIScreen.mainScreen().bounds.width / assetTrack.naturalSize.height
let scaleFactor = CGAffineTransformMakeScale(scaleToFitRatio, scaleToFitRatio)
instruction.setTransform(CGAffineTransformConcat(assetTrack.preferredTransform, scaleFactor),
atTime: kCMTimeZero)
} else {
// If it is landscape then check for incorrect orientation and correct if needed, then return instructon to re-orient and scale.
let scaleFactor = CGAffineTransformMakeScale(scaleToFitRatio, scaleToFitRatio)
var concat = CGAffineTransformConcat(CGAffineTransformConcat(assetTrack.preferredTransform, scaleFactor), CGAffineTransformMakeTranslation(0, UIScreen.mainScreen().bounds.width / 2))
if assetInfo.orientation == .Down {
let fixUpsideDown = CGAffineTransformMakeRotation(CGFloat(M_PI))
let windowBounds = UIScreen.mainScreen().bounds
let yFix = assetTrack.naturalSize.height + windowBounds.height
let centerFix = CGAffineTransformMakeTranslation(assetTrack.naturalSize.width, yFix)
concat = CGAffineTransformConcat(CGAffineTransformConcat(fixUpsideDown, centerFix), scaleFactor)
}
instruction.setTransform(concat, atTime: kCMTimeZero)
}
答案 0 :(得分：0)
不应该在第一个+第二个音轨持续时间之后将第二个音轨的不透明度设置为0.0，而不是现在的音量：
secondInstruction.setOpacity(0.0, atTime: secondAsset.duration)
为：
secondInstruction.setOpacity(0.0, atTime: firstAsset.duration+secondAsset.duration) //(Untested, but the idea is there).