Video cracked while merging videos using AVMutableComposition - ios

Question

I'm merging the videos using AVMutableComposition with the below code,
- (void)MergeAndSave_internal{
AVMutableComposition *composition = [AVMutableComposition composition];
AVMutableCompositionTrack *compositionVideoTrack = [composition addMutableTrackWithMediaType:AVMediaTypeVideo preferredTrackID:kCMPersistentTrackID_Invalid];
AVMutableCompositionTrack *compositionAudioTrack = [composition addMutableTrackWithMediaType:AVMediaTypeAudio preferredTrackID:kCMPersistentTrackID_Invalid];
AVMutableVideoComposition *videoComposition = [AVMutableVideoComposition videoComposition];
videoComposition.frameDuration = CMTimeMake(1,30);
videoComposition.renderScale = 1.0;
AVMutableVideoCompositionInstruction *instruction = [AVMutableVideoCompositionInstruction videoCompositionInstruction];
AVMutableVideoCompositionLayerInstruction *layerInstruction = [AVMutableVideoCompositionLayerInstruction videoCompositionLayerInstructionWithAssetTrack:compositionVideoTrack];
NSLog(#"%#",videoPathArray);
float time = 0;
CMTime startTime = kCMTimeZero;
for (int i = 0; i<videoPathArray.count; i++) {
AVURLAsset *sourceAsset = [AVURLAsset URLAssetWithURL:[NSURL fileURLWithPath:[videoPathArray objectAtIndex:i]] options:[NSDictionary dictionaryWithObject:[NSNumber numberWithBool:YES] forKey:AVURLAssetPreferPreciseDurationAndTimingKey]];
NSError *error = nil;
BOOL ok = NO;
AVAssetTrack *sourceVideoTrack = [[sourceAsset tracksWithMediaType:AVMediaTypeVideo] objectAtIndex:0];
AVAssetTrack *sourceAudioTrack = [[sourceAsset tracksWithMediaType:AVMediaTypeAudio] objectAtIndex:0];
CGSize temp = CGSizeApplyAffineTransform(sourceVideoTrack.naturalSize, sourceVideoTrack.preferredTransform);
CGSize size = CGSizeMake(fabsf(temp.width), fabsf(temp.height));
CGAffineTransform transform = sourceVideoTrack.preferredTransform;
videoComposition.renderSize = sourceVideoTrack.naturalSize;
if (size.width > size.height) {
[layerInstruction setTransform:transform atTime:CMTimeMakeWithSeconds(time, 30)];
} else {
float s = size.width/size.height;
CGAffineTransform newe = CGAffineTransformConcat(transform, CGAffineTransformMakeScale(s,s));
float x = (size.height - size.width*s)/2;
CGAffineTransform newer = CGAffineTransformConcat(newe, CGAffineTransformMakeTranslation(x, 0));
[layerInstruction setTransform:newer atTime:CMTimeMakeWithSeconds(time, 30)];
}
if(i==0){
[compositionVideoTrack setPreferredTransform:sourceVideoTrack.preferredTransform];
}
ok = [compositionVideoTrack insertTimeRange:CMTimeRangeMake(kCMTimeZero, [sourceAsset duration]) ofTrack:sourceVideoTrack atTime:startTime error:&error];
ok = [compositionAudioTrack insertTimeRange:CMTimeRangeMake(kCMTimeZero, [sourceAsset duration]) ofTrack:sourceAudioTrack atTime:startTime error:nil];
if (!ok) {
{
[radialView4 setHidden:YES];
NSLog(#"Export failed: %#", [[self.exportSession error] localizedDescription]);
UIAlertView *alert = [[UIAlertView alloc] initWithTitle:#"Error" message:#"Something Went Wrong :(" delegate:nil cancelButtonTitle:#"Ok" otherButtonTitles: nil, nil];
[alert show];
[radialView4 setHidden:YES];
break;
}
}
startTime = CMTimeAdd(startTime, [sourceAsset duration]);
}
instruction.layerInstructions = [NSArray arrayWithObject:layerInstruction];
instruction.timeRange = compositionVideoTrack.timeRange;
videoComposition.instructions = [NSArray arrayWithObject:instruction];
NSArray *paths = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES);
NSString *documentsDirectory = [paths objectAtIndex:0];
NSString *myPathDocs = [documentsDirectory stringByAppendingPathComponent:
[NSString stringWithFormat:#"RampMergedVideo.mov"]];
unlink([myPathDocs UTF8String]);
NSURL *url = [NSURL fileURLWithPath:myPathDocs];
AVAssetExportSession *exporter = [[AVAssetExportSession alloc] initWithAsset:composition
presetName:AVAssetExportPreset1280x720];
exporter.outputURL=url;
exporter.outputFileType = AVFileTypeQuickTimeMovie;
exporter.shouldOptimizeForNetworkUse = YES;
[exporter exportAsynchronouslyWithCompletionHandler:^{
dispatch_async(dispatch_get_main_queue(), ^{
switch ([exporter status]) {
case AVAssetExportSessionStatusFailed:
NSLog(#"Export failed: %#", [exporter error]);
break;
case AVAssetExportSessionStatusCancelled:
NSLog(#"Export canceled");
break;
case AVAssetExportSessionStatusCompleted:{
NSLog(#"Export successfully");
}
default:
break;
}
if (exporter.status != AVAssetExportSessionStatusCompleted){
NSLog(#"Retry export");
}
});
}];
}
But video looks cracked while saving to system and playing in quick time player. I think that the problem in CFAffline transform. Can anyone please advice ?
Here's the cracked screen in the middle of the video :

Answer 1

You haven't set videoComposition to the AVAssetExportSession. Try doing this exporter.videoComposition = videoComposition;. Havent tried this though but should work.