How to merge Audio and video? - iphone

Question

I'm merging video with video and audio with video. It is working fine in video with video case but when audio file merge that give black screen. I don't know what thing I'm going to wrong with this code
-(void)mergeAllMediaAtTime:(NSMutableArray*)startTimeArray {
NSURL *firstURL = [NSURL fileURLWithPath:[urlArray objectAtIndex:counter]];
firstAsset = [AVAsset assetWithURL:firstURL];
NSString* videoDirPath = [NSHomeDirectory() stringByAppendingPathComponent:#"Documents/Crop Videos"];
NSString* fileName = [VideoAndAudioNameArray objectAtIndex:counter];
NSString *pSecondVideoPath = [videoDirPath stringByAppendingPathComponent:fileName];
NSURL *secondURL = [NSURL fileURLWithPath:pSecondVideoPath];
secondAsset = [AVAsset assetWithURL:secondURL];
if(firstAsset !=nil && secondAsset!=nil)
{
AVVideoComposition *origionalComposition = [AVVideoComposition videoCompositionWithPropertiesOfAsset:firstAsset];
//Create AVMutableComposition Object.This object will hold our multiple AVMutableCompositionTrack.
AVMutableComposition* mixComposition = [[AVMutableComposition alloc] init];
//VIDEO TRACK
AVMutableCompositionTrack *firstTrack = [mixComposition addMutableTrackWithMediaType:AVMediaTypeVideo preferredTrackID:kCMPersistentTrackID_Invalid];
AVAssetTrack* track = [[firstAsset tracksWithMediaType:AVMediaTypeVideo] objectAtIndex:0];
[firstTrack insertTimeRange:CMTimeRangeMake(kCMTimeZero, firstAsset.duration) ofTrack:track atTime:kCMTimeZero error:nil];
int time = [[startTimeArray objectAtIndex:counter] intValue];
CMTime pTime = CMTimeMake(time, 1);
///////////////////////
AVMutableCompositionTrack *secondTrack;
if ([[fileName pathExtension] isEqualToString:#"mov"])
{
secondTrack = [mixComposition addMutableTrackWithMediaType:AVMediaTypeVideo preferredTrackID:kCMPersistentTrackID_Invalid];
[secondTrack insertTimeRange:CMTimeRangeMake(kCMTimeZero, secondAsset.duration) ofTrack:[[secondAsset tracksWithMediaType:AVMediaTypeVideo] objectAtIndex:0] atTime:pTime error:nil];
}
// If Audio file
else
{
secondTrack = [mixComposition addMutableTrackWithMediaType:AVMediaTypeAudio preferredTrackID:kCMPersistentTrackID_Invalid];
[secondTrack insertTimeRange:CMTimeRangeMake(kCMTimeZero, secondAsset.duration) ofTrack:[[secondAsset tracksWithMediaType:AVMediaTypeAudio] objectAtIndex:0] atTime:pTime error:nil];
NSLog(#"Audio file's Merging");
}
/****** First Video *********/
AVMutableVideoCompositionInstruction * MainInstruction = [AVMutableVideoCompositionInstruction videoCompositionInstruction];
MainInstruction.timeRange = CMTimeRangeMake(kCMTimeZero, firstAsset.duration);
MainInstruction.backgroundColor = [[UIColor clearColor] CGColor];
//FIXING ORIENTATION//
AVMutableVideoCompositionLayerInstruction *FirstlayerInstruction = [AVMutableVideoCompositionLayerInstruction videoCompositionLayerInstructionWithAssetTrack:firstTrack];
AVAssetTrack *FirstAssetTrack = [[firstAsset tracksWithMediaType:AVMediaTypeVideo] objectAtIndex:0];
[FirstlayerInstruction setTransform:FirstAssetTrack.preferredTransform atTime:kCMTimeZero];
[FirstlayerInstruction setOpacity:0.0 atTime:firstAsset.duration];
if ([[fileName pathExtension] isEqualToString:#"mov"])
{
/****** Second Video *********/
AVMutableVideoCompositionLayerInstruction *SecondlayerInstruction = [AVMutableVideoCompositionLayerInstruction videoCompositionLayerInstructionWithAssetTrack:secondTrack];
AVAssetTrack *SecondAssetTrack = [[secondAsset tracksWithMediaType:AVMediaTypeVideo] objectAtIndex:0];
[SecondlayerInstruction setOpacity:1.0 atTime:pTime];
UIImageOrientation SecondAssetOrientation_ = UIImageOrientationUp;
BOOL isSecondAssetPortrait_ = NO;
CGAffineTransform secondTransform = SecondAssetTrack.preferredTransform;
if(secondTransform.a == 0 && secondTransform.b == 1.0 && secondTransform.c == -1.0 && secondTransform.d == 0) {SecondAssetOrientation_= UIImageOrientationRight; isSecondAssetPortrait_ = YES;}
if(secondTransform.a == 0 && secondTransform.b == -1.0 && secondTransform.c == 1.0 && secondTransform.d == 0) {SecondAssetOrientation_ = UIImageOrientationLeft; isSecondAssetPortrait_ = YES;}
if(secondTransform.a == 1.0 && secondTransform.b == 0 && secondTransform.c == 0 && secondTransform.d == 1.0) {SecondAssetOrientation_ = UIImageOrientationUp;}
if(secondTransform.a == -1.0 && secondTransform.b == 0 && secondTransform.c == 0 && secondTransform.d == -1.0) {SecondAssetOrientation_ = UIImageOrientationDown;}
CGFloat SecondAssetScaleToFitRatioOfWidth = nRenderWidth/SecondAssetTrack.naturalSize.width;
if(isSecondAssetPortrait_)
{
CGFloat SecondAssetScaleToFitRatioOfHeight = nRenderWidth/SecondAssetTrack.naturalSize.height;
CGAffineTransform SecondAssetScaleFactor = CGAffineTransformMakeScale(SecondAssetScaleToFitRatioOfWidth,SecondAssetScaleToFitRatioOfHeight);
[SecondlayerInstruction setTransform:CGAffineTransformConcat(CGAffineTransformMakeScale(1.0f,1.0f), SecondAssetScaleFactor) atTime:kCMTimeZero];
//CGAffineTransformConcat(CGAffineTransformMakeScale(1.0f,1.0f), SecondAssetScaleFactor)
}
else
{
CGFloat SecondAssetScaleToFitRatioOfWidth = nRenderWidth/SecondAssetTrack.naturalSize.width;
CGFloat SecondAssetScaleToFitRatioOfHeight = nRenderWidth/SecondAssetTrack.naturalSize.height;
CGAffineTransform SecondAssetScaleFactor = CGAffineTransformMakeScale(SecondAssetScaleToFitRatioOfWidth,SecondAssetScaleToFitRatioOfHeight);
//[SecondlayerInstruction setTransform:CGAffineTransformConcat(CGAffineTransformConcat(SecondAssetTrack.preferredTransform, SecondAssetScaleFactor),CGAffineTransformMakeTranslation(0, 160)) atTime:firstAsset.duration];
[SecondlayerInstruction setTransform:CGAffineTransformConcat(SecondAssetScaleFactor ,CGAffineTransformMakeTranslation(1, 1)) atTime:kCMTimeZero];
//CGAffineTransformConcat(CGAffineTransformMakeScale(1.0f,1.0f),CGAffineTransformMakeTranslation(0, 100))
}
[SecondlayerInstruction setOpacity:0.0 atTime:CMTimeAdd(pTime, secondAsset.duration)];
MainInstruction.layerInstructions = [NSArray arrayWithObjects:SecondlayerInstruction, FirstlayerInstruction,nil];
}
AVMutableVideoComposition *MainCompositionInst = [AVMutableVideoComposition videoComposition];
MainCompositionInst.instructions = [NSArray arrayWithObject:MainInstruction];
MainCompositionInst.frameDuration = origionalComposition.frameDuration;
MainCompositionInst.renderScale = 1.0;
MainCompositionInst.renderSize = CGSizeMake(nRenderWidth, nRenderHeight);
NSArray *paths = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES);
NSString *documentsDirectory = [paths objectAtIndex:0];
NSString *myPathDocs = [documentsDirectory stringByAppendingPathComponent:[NSString stringWithFormat:#"mergeVideo_%d.mov",arc4random() % 1000]];
NSURL *url = [NSURL fileURLWithPath:myPathDocs];
[urlArray addObject:myPathDocs];
AVAssetExportSession *exporter = [[AVAssetExportSession alloc] initWithAsset:mixComposition presetName:AVAssetExportPresetMediumQuality];
exporter.outputURL=url;
exporter.outputFileType = AVFileTypeQuickTimeMovie;
exporter.videoComposition = MainCompositionInst;
exporter.shouldOptimizeForNetworkUse = YES;
[exporter exportAsynchronouslyWithCompletionHandler:^
{
dispatch_async(dispatch_get_main_queue(), ^{
[self exportDidFinish:exporter];
}
});
}];
}
}

Answer 1

In that case,you start with your audio from end of the video frames. You can use "atTime:kCMTimeZero".
i.e: shown in below(code below)
else
{
secondTrack = [mixComposition addMutableTrackWithMediaType:AVMediaTypeAudio preferredTrackID:kCMPersistentTrackID_Invalid];
[secondTrack insertTimeRange:CMTimeRangeMake(kCMTimeZero, secondAsset.duration) ofTrack:[[secondAsset tracksWithMediaType:AVMediaTypeAudio] objectAtIndex:0] atTime:kCMTimeZero error:nil];
NSLog(#"Audio file's Merging");
}