How to set Background image to AVMutableVideoCompositionInstruction - ios

Question

I set the backgroundColor its Working fine, but i am not able to set the background image.
AVMutableVideoCompositionInstruction * mainInstruction = [AVMutableVideoCompositionInstruction videoCompositionInstruction];
mainInstruction.timeRange = CMTimeRangeMake(kCMTimeZero,assetWithMaxTime.duration);
mainInstruction.enablePostProcessing = NO;
mainInstruction.backgroundColor =[UIColor yellowColor].CGColor;

Answer 1

After trying several things finally I got a way to work it. To make it work need to use a blank video/audio track. Then add background image an overlay to this blank video layer. Ten export it and combine the original asset(video) and exported asset(asset) and export the final asset(video).
Add overlay
- (void)addOverlayImage:(UIImage *)overlayImage ToVideo:(AVMutableVideoComposition *)composition inSize:(CGSize)size {
// 1 - set up the overlay
CALayer *overlayLayer = [CALayer layer];
[overlayLayer setContents:(id)[overlayImage CGImage]];
overlayLayer.frame = CGRectMake(0, 0, size.width, size.height);
[overlayLayer setMasksToBounds:YES];
// 2 - set up the parent layer
CALayer *parentLayer = [CALayer layer];
CALayer *videoLayer = [CALayer layer];
parentLayer.frame = CGRectMake(0, 0, size.width, size.height);
videoLayer.frame = CGRectMake(0, 0, size.width, size.height);
[parentLayer addSublayer:videoLayer];
[parentLayer addSublayer:overlayLayer];
// 3 - apply magic
composition.animationTool = [AVVideoCompositionCoreAnimationTool
videoCompositionCoreAnimationToolWithPostProcessingAsVideoLayer:videoLayer inLayer:parentLayer];
}
- (void)getBackgroundVideoAssetWithcompletion:(void (^)(AVAsset *bgAsset))completionBlock {
NSString *path = [[NSBundle mainBundle] pathForResource:#"blank_video" ofType:#"mp4"];
NSURL *trackUrl = [NSURL fileURLWithPath:path];
AVAsset *asset = [AVAsset assetWithURL:trackUrl];
AVAssetTrack *track = [[asset tracksWithMediaType:AVMediaTypeVideo] objectAtIndex:0];
CMTimeRange range = CMTimeRangeMake(kCMTimeZero, [asset duration]);
AVMutableComposition* mixComposition = [AVMutableComposition composition];
AVMutableCompositionTrack *compositionVideoTrack = [mixComposition addMutableTrackWithMediaType:AVMediaTypeVideo preferredTrackID:kCMPersistentTrackID_Invalid];
[compositionVideoTrack insertTimeRange:range ofTrack:[[asset tracksWithMediaType:AVMediaTypeVideo] objectAtIndex:0] atTime:kCMTimeZero error:nil];
CGAffineTransform videoTransform = track.preferredTransform;
CGSize naturalSize = CGSizeApplyAffineTransform(track.naturalSize, videoTransform);
naturalSize = CGSizeMake(fabs(naturalSize.width), fabs(naturalSize.height));
AVMutableVideoComposition *composition = [AVMutableVideoComposition videoCompositionWithPropertiesOfAsset:asset];
UIImage *img = [self imageWithImage:[UIImage imageNamed:#"white_image"] convertToSize:naturalSize];
[self addOverlayImage:img ToVideo:composition inSize:naturalSize];
AVMutableVideoCompositionInstruction *instruction = [AVMutableVideoCompositionInstruction videoCompositionInstruction];
instruction.timeRange = range;
composition.instructions = #[instruction];
AVAssetExportSession *_assetExport = [[AVAssetExportSession alloc] initWithAsset:mixComposition presetName:AVAssetExportPresetMediumQuality];
_assetExport.videoComposition = composition;
NSString *exportPath = [NSTemporaryDirectory() stringByAppendingPathComponent:[NSString stringWithFormat:#"exported-%d.mov", arc4random() % 100000]];
unlink([exportPath UTF8String]);
NSURL *exportUrl = [NSURL fileURLWithPath:exportPath];
_assetExport.outputFileType = AVFileTypeQuickTimeMovie;
_assetExport.outputURL = exportUrl;
_assetExport.shouldOptimizeForNetworkUse = YES;
[_assetExport exportAsynchronouslyWithCompletionHandler:^{
switch (_assetExport.status) {
case AVAssetExportSessionStatusFailed:
break;
case AVAssetExportSessionStatusExporting:
break;
case AVAssetExportSessionStatusCompleted:{
dispatch_async(dispatch_get_main_queue(), ^{
NSLog(#"Successful!!!");
AVAsset *finalAsset = [AVAsset assetWithURL:_assetExport.outputURL];
completionBlock(finalAsset);
});
}
break;
default:
break;
}
}];
}
Now there is a video asset with an overlay image. Only thing is remain to combine original video and the exported video asset. Exported asset should be bottom layer and original should be top layer.