Trying to watermark a image on video using AVFoundation - ios

Question

I have taken a png image and a video for watermarking, both are portrait. And I have done it as watermark an image at video.
After watermarking, got a merged video in landscape mode and it is flipped by 90 degree in anti clock direction.
I am not able to find out the exact reason why video got flipped from portrait to landscape mode. While image is showing stretch portrait.
Please help. Thanks in advance.
Used below code:-
- (void)addWatermarkAtVideoFile:(NSURL *)videoURL image:(UIImage *)image withConvertedVideoUUID:(NSString *)convertedVideoUUID response:(void(^)(BOOL success, NSString *videoUUID, NSURL *videoPath))responseBlock {
AVURLAsset* videoAsset = [[AVURLAsset alloc]initWithURL:videoURL options:nil];
AVMutableComposition* mixComposition = [AVMutableComposition composition];
AVAssetTrack *clipVideoTrack = [[videoAsset tracksWithMediaType:AVMediaTypeVideo] objectAtIndex:0];
if(clipVideoTrack) {
AVMutableCompositionTrack *compositionVideoTrack = [mixComposition addMutableTrackWithMediaType:AVMediaTypeVideo preferredTrackID:kCMPersistentTrackID_Invalid];
[compositionVideoTrack insertTimeRange:CMTimeRangeMake(kCMTimeZero, videoAsset.duration) ofTrack:clipVideoTrack atTime:kCMTimeZero error:nil];
[compositionVideoTrack setPreferredTransform:[[[videoAsset tracksWithMediaType:AVMediaTypeVideo] objectAtIndex:0] preferredTransform]];
}
AVAssetTrack *clipAudioTrack = [[videoAsset tracksWithMediaType:AVMediaTypeAudio] objectAtIndex:0];
if(clipAudioTrack) {
AVMutableCompositionTrack *compositionAudioTrack = [mixComposition addMutableTrackWithMediaType:AVMediaTypeAudio preferredTrackID:kCMPersistentTrackID_Invalid];
[compositionAudioTrack insertTimeRange:CMTimeRangeMake(kCMTimeZero, videoAsset.duration) ofTrack:clipAudioTrack atTime:kCMTimeZero error:nil];
}
CGSize sizeOfVideo=[videoAsset naturalSize];
//Image of watermark
UIImage *myImage = image;
CALayer *layerCa = [CALayer layer];
layerCa.contents = (id)myImage.CGImage;
layerCa.frame = CGRectMake(0, 0, sizeOfVideo.width, sizeOfVideo.height);
layerCa.opacity = 1.0;
CALayer *parentLayer=[CALayer layer];
CALayer *videoLayer=[CALayer layer];
parentLayer.frame=CGRectMake(0, 0, sizeOfVideo.width, sizeOfVideo.height);
videoLayer.frame=CGRectMake(0, 0, sizeOfVideo.width, sizeOfVideo.height);
[parentLayer addSublayer:videoLayer];
[parentLayer addSublayer:layerCa];
AVMutableVideoComposition *videoComposition=[AVMutableVideoComposition videoComposition] ;
videoComposition.frameDuration=CMTimeMake(1, 30);
videoComposition.renderSize=sizeOfVideo;
videoComposition.animationTool=[AVVideoCompositionCoreAnimationTool videoCompositionCoreAnimationToolWithPostProcessingAsVideoLayer:videoLayer inLayer:parentLayer];
AVMutableVideoCompositionInstruction *instruction = [AVMutableVideoCompositionInstruction videoCompositionInstruction];
instruction.timeRange = CMTimeRangeMake(kCMTimeZero, [mixComposition duration]);
AVAssetTrack *videoTrack = [[mixComposition tracksWithMediaType:AVMediaTypeVideo] objectAtIndex:0];
AVMutableVideoCompositionLayerInstruction* layerInstruction = [AVMutableVideoCompositionLayerInstruction videoCompositionLayerInstructionWithAssetTrack:videoTrack];
instruction.layerInstructions = [NSArray arrayWithObject:layerInstruction];
videoComposition.instructions = [NSArray arrayWithObject: instruction];
//Creating temp path to save the converted video
NSString* myDocumentPath = [self getDocumentDirectoryPathWithFileName:convertedVideoUUID];
NSURL *outputFileURL = [[NSURL alloc] initFileURLWithPath:myDocumentPath];
//Check if the file already exists then remove the previous file
[self removeFileIfExistAtPAth:myDocumentPath];
AVAssetExportSession *exportSession = [[AVAssetExportSession alloc] initWithAsset:mixComposition presetName:AVAssetExportPresetHighestQuality];
exportSession.videoComposition=videoComposition;
exportSession.outputURL = outputFileURL;
exportSession.outputFileType = AVFileTypeQuickTimeMovie;
[exportSession exportAsynchronouslyWithCompletionHandler:^{
switch (exportSession.status)
{
case AVAssetExportSessionStatusCompleted:
NSLog(#"Export OK");
[self saveInPhotoAlbum:myDocumentPath];
break;
case AVAssetExportSessionStatusFailed:
NSLog (#"AVAssetExportSessionStatusFailed: %#", exportSession.error);
break;
case AVAssetExportSessionStatusCancelled:
NSLog(#"Export Cancelled");
break;
}
BOOL statusSuccess = [exportSession status] == AVAssetExportSessionStatusCompleted;
responseBlock(statusSuccess ? YES : NO, statusSuccess ? convertedVideoUUID : nil, statusSuccess ? outputFileURL : nil);
}];
}

Answer 1

I think it's the default behavior with AVFoundation, it's probably not linked to the watermark feature.
You could use CGAffineTransform :
if(height > width) {
CGAffineTransform rotationTransform = CGAffineTransformMakeRotation(M_PI_2);
[layerInstruction setTransform:rotationTransform atTime:kCMTimeZero];
}

Answer 2

The naturalSize of AVAsset doesn't consider the eventual rotation of a video.
If you want to place tour watermark correctly consider using the renderSize of the AVMutableVideoComposition or apply some transformations.
This snippet gives you the actual orientation for an asset:
func orientationForAsset(_ asset: AVAsset) -> (orientation: UIImageOrientation, isPortrait: Bool) {
let videoTrack = asset.tracks(withMediaType: AVMediaTypeVideo).first!
let transformMatrix = videoTrack.preferredTransform
return orientationFromTransform(transformMatrix)
}
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)
}
With this one you can get the actual size considering the rotation.
func resolutionSizeForAsset(_ asset: AVAsset) -> CGSize? {
guard let track = asset.tracks(withMediaType: AVMediaTypeVideo).first else { return nil }
let size = track.naturalSize.applying(track.preferredTransform)
return CGSize(width: fabs(size.width), height: fabs(size.height))
}