Video not rotating using AVMutableVideoCompositionLayerInstruction

Question

I'm trying to merge two videos I get after recording using the camera as a UIImagePickerController. I've succeeded with combining the videos into one but I have some problems with the orientation of the videos.

As I've understood it with the UIImagePickerController is that all videos are captured in landscape, this means that the videos recorded in portrait are rotated 90°.

After each recording I add the new video to an array

func imagePickerController(picker: UIImagePickerController!, didFinishPickingMediaWithInfo info:NSDictionary) {
    let tempImage = info[UIImagePickerControllerMediaURL] as NSURL
    videos.append(tempImage)
    let pathString = tempImage.relativePath
    self.dismissViewControllerAnimated(true, completion: {})
}

Then when I want to merge I go through each video and create an instruction and adds the instruction to another array

var composition = AVMutableComposition()
let trackVideo:AVMutableCompositionTrack = composition.addMutableTrackWithMediaType(AVMediaTypeVideo, preferredTrackID: CMPersistentTrackID())
let trackAudio:AVMutableCompositionTrack = composition.addMutableTrackWithMediaType(AVMediaTypeAudio, preferredTrackID: CMPersistentTrackID())
var insertTime = kCMTimeZero

for i in 0...(videos.count-1){
    let moviePathUrl = videos[i]
    let sourceAsset = AVURLAsset(URL: moviePathUrl, options: nil)

    let tracks = sourceAsset.tracksWithMediaType(AVMediaTypeVideo)
    let audios = sourceAsset.tracksWithMediaType(AVMediaTypeAudio)

    if tracks.count > 0{
        var videoDuration = CMTimeRangeMake(kCMTimeZero, sourceAsset.duration);

        let assetTrack:AVAssetTrack = tracks[0] as AVAssetTrack
        let assetTrackAudio:AVAssetTrack = audios[0] as AVAssetTrack

        trackVideo.insertTimeRange(videoDuration, ofTrack: assetTrack, atTime: insertTime, error: nil)
        trackAudio.insertTimeRange(videoDuration, ofTrack: assetTrackAudio, atTime: insertTime, error: nil)

        //Rotate
        var rotater = AVMutableVideoCompositionLayerInstruction(assetTrack: assetTrack)
        rotater.setTransform(assetTrack.preferredTransform, atTime: insertTime)
        rotater.setOpacity(0.0, atTime: CMTimeAdd(insertTime, sourceAsset.duration))
        instructions.append(rotater)

        //Resize
        var resizer = AVMutableVideoCompositionLayerInstruction(assetTrack: assetTrack)
        resizer.setCropRectangle(CGRectMake(0, 0, 300, 300), atTime: insertTime)
        instructions.append(resizer)

        insertTime = CMTimeAdd(insertTime, sourceAsset.duration)

    }
}

When I've created all the instructions I add them to the main instruction and create the export session.

var instruction = AVMutableVideoCompositionInstruction();
instruction.timeRange = CMTimeRangeMake(kCMTimeZero, insertTime);

instruction.layerInstructions = instructions;
var mainCompositionInst = AVMutableVideoComposition()
mainCompositionInst.instructions = NSArray(object: instruction)

mainCompositionInst.frameDuration = CMTimeMake(1, 60);
mainCompositionInst.renderSize = CGSizeMake(300, 300);

var exporter = AVAssetExportSession(asset: composition, presetName: AVAssetExportPresetHighestQuality)
exporter.videoComposition = mainCompositionInst;

What am I missing?

Answer 1

Try using trackVideo in the initializer for your layer Instruction so it will use the AVMutableCompositionTrack's trackID rather than the source asset's trackID

Update:

You only need one AVMutableVideoCompositionLayerInstruction, so declare it before the loop with the AVMutableCompositionTrack as the parameter. Then on each iteration of the loop, set the necessary properties of the layer instruction (transform, crop rect) for the current video asset you're working with. You're controlling how the video content in the composition track should be displayed at each insert time.

At the end, place the single layerInstruction in the instructions array, and use that in the video composition.

var layerInstruction = AVMutableVideoCompositionLayerInstruction(assetTrack: trackVideo)
for i in 0...(videos.count-1){
   //...your other code here

   layerInstruction.setTransform(assetTrack.preferredTransform, atTime: insertTime)
   layerInstruction.setCropRectangle(CGRectMake(0, 0, 300, 300), atTime: insertTime)
}

var instruction = AVMutableVideoCompositionInstruction();
instruction.timeRange = CMTimeRangeMake(kCMTimeZero, insertTime);

instruction.layerInstructions = NSArray(object: layerInstruction);
var mainCompositionInst = AVMutableVideoComposition()
mainCompositionInst.instructions = NSArray(object: instruction)