Concat video sequences - ios

Question

I'm getting AVAssetExportSessionStatusFailed when trying to concat video sequences with this message:
Export Failed with error messsage: Error
Domain=AVFoundationErrorDomain Code=-11841 "Operation Stopped"
UserInfo=0x170675cc0 {NSLocalizedDescription=Operation Stopped,
NSLocalizedFailureReason=The video could not be composed.}, Operation
Stopped
Here is my code:
self.finalComposition = [AVMutableComposition composition];
self.finalCompositionTrack = [_finalComposition addMutableTrackWithMediaType:AVMediaTypeVideo preferredTrackID:kCMPersistentTrackID_Invalid];
self.finalCompositionAudioTrack = [_finalComposition addMutableTrackWithMediaType:AVMediaTypeAudio preferredTrackID:kCMPersistentTrackID_Invalid];
CMTime currentTime = kCMTimeZero;
AVURLAsset *asset = nil;
NSMutableArray *audioTracks = [[NSMutableArray alloc] init];
NSMutableArray *videos = [[NSMutableArray alloc] init];
for (int videoCounter = 0; videoCounter < _videoArray.count ; videoCounter++)
{
id object = [_videoArray objectAtIndex:videoCounter];
if ([object isKindOfClass:[MVideoRecord class]])
{
MVideoRecord *video = object;
NSURL *url = [NSURL fileURLWithPath:video.pathToVideo];
NSFileManager *fileManager = [NSFileManager defaultManager];
if (![fileManager fileExistsAtPath:video.pathToVideo])
{
[self showError:#"Invalid video"];
}
NSDictionary *options = [NSDictionary dictionaryWithObject:[NSNumber numberWithBool:YES] forKey:AVURLAssetPreferPreciseDurationAndTimingKey];
asset = [AVURLAsset URLAssetWithURL:url options:options];
NSError *error = nil;
if (!self.videoCompostion)
{
self.videoCompostion = [AVMutableVideoComposition videoComposition];
self.videoCompostion.frameDuration = CMTimeMake(1, 30);
self.videoCompostion.renderSize = CGSizeMake(640, 360);
self.videoCompositionInstruction = [AVMutableVideoCompositionInstruction videoCompositionInstruction];
videoCompositionInstruction.timeRange = CMTimeRangeMake(kCMTimeZero, totalTime);
self.videoCompositionLayerInstruction = [AVMutableVideoCompositionLayerInstruction videoCompositionLayerInstructionWithAssetTrack:self.finalCompositionTrack];
}
for (AVAssetTrack *track in asset.tracks)
{
CGSize size = track.naturalSize;
if(track.naturalTimeScale == 600)
{
CGAffineTransform transform = [track preferredTransform];
int orientation = [self orientationForTrack: asset];
if (orientation < 2)
{
float x = 640/size.width;
float y = 360/size.height;
CGAffineTransform videoScale = CGAffineTransformMakeScale(x, y);
[_videoCompositionLayerInstruction setTransform:CGAffineTransformConcat(transform, videoScale) atTime:currentTime]; }
else
{
float s = 480/size.height;
CGAffineTransform new = CGAffineTransformConcat(transform, CGAffineTransformMakeScale(s,s));
[_videoCompositionLayerInstruction setTransform:new atTime:currentTime];
}
if (![_finalCompositionTrack insertTimeRange:CMTimeRangeMake(CMTimeMakeWithSeconds(video.videoStart.doubleValue, 600), CMTimeMakeWithSeconds(video.videoEnd.doubleValue, 600)) ofTrack:track atTime:currentTime error:&error])
{
[self showError:error.localizedFailureReason];
}
}
else if (track.naturalTimeScale == 44100)
{
CMTime start = kCMTimeZero;
CMTime duration = CMTimeMakeWithSeconds(video.videoEnd.doubleValue, 600);
NSError *error;
[finalCompositionAudioTrack insertTimeRange:CMTimeRangeMake(start, duration)
ofTrack:[[track.asset tracksWithMediaType:AVMediaTypeAudio] objectAtIndex:0] atTime:currentTime error:&error];
NSLog(#"%#", error);
}
}
currentTime = CMTimeAdd(currentTime, CMTimeMake(video.videoEnd.doubleValue*600, 600));
}
}
//apply the translation to video composition
_videoCompositionInstruction.layerInstructions = [NSArray arrayWithObject: _videoCompositionLayerInstruction];
_videoCompostion.instructions = [NSArray arrayWithObject:_videoCompositionInstruction];
//get filepath of last object...
MVideoRecord *lastRecord = [_videoArray objectAtIndex:_videoArray.count - 2];
NSString *finalExportURLString = [lastRecord.pathToVideo stringByReplacingOccurrencesOfString:#".MOV" withString:#"_finalExport.mp4"];
//testing fix for video missing audio after final export
//string = [exportURL.absoluteString stringByReplacingOccurrencesOfString:#".MOV" withString:#"_finalExport.MOV"];
// File Management
NSFileManager *fileManager = [NSFileManager defaultManager];
self.finalExportURL = [NSURL fileURLWithPath:finalExportURLString];
self.finalExportSession = [[AVAssetExportSession alloc] initWithAsset:_finalComposition presetName:TEST_EXPORT_SESSION_QUALITY];
if ([fileManager fileExistsAtPath:finalExportURL.path])
{
NSError *fileError = nil;
if (![fileManager removeItemAtPath:finalExportURLString error:&fileError])
{
DCLog(#"Error removing old path: %#", fileError.localizedDescription);
}
}
_finalExportSession.outputURL = self.finalExportURL;
_finalExportSession.outputFileType = #"public.mpeg-4";
_finalExportSession.videoComposition = self.videoCompostion;
[self.finalExportSession exportAsynchronouslyWithCompletionHandler:^{
switch (_finalExportSession.status)
{ case AVAssetExportSessionStatusFailed:
{
DCLog(#"Export Failed with error messsage: %#, %#", _finalExportSession.error, _finalExportSession.error.localizedDescription);
break;
}
case AVAssetExportSessionStatusCompleted:
{
DCLog(#"Export Success");
break;
}
};
}];
What am I doing wrong?
The most weird, if I change:
[finalCompositionAudioTrack insertTimeRange:CMTimeRangeMake(start, duration)
ofTrack:[[track.asset tracksWithMediaType:AVMediaTypeAudio] objectAtIndex:0] atTime:currentTime error:&error];
to:
[finalCompositionAudioTrack insertTimeRange:CMTimeRangeMake(start, duration)
ofTrack:[[track.asset tracksWithMediaType:AVMediaTypeAudio] objectAtIndex:0] atTime:kCMTimeZero error:&error];
It works, but of course, the audio is played wrong. The audio for first video plays for the second one.

Answer 1

I fixed my problem by creating AVMutableCompositionTrack for each audio track. I moved the code below to inside the loop and it worked.
compositionAudioTrack = [_finalComposition addMutableTrackWithMediaType:AVMediaTypeAudio preferredTrackID:kCMPersistentTrackID_Invalid];