video uploaded from iphone app to youtube have no sound - iphone

Question

I am developing an iphone app which records its activities(screen recording) and uploads to youtube. Firstly the video has no sound before upload the app mixes some sound with the video. The output video plays in my iphone and ipad without any problem but the uploaded video plays without sound(have a sound at starting only). My video format is .mov.
my code to mix sound and video is
as in purplelilgirl's tutorial
-(NSString*) processVideo: (NSURL*) videoUrl{ NSLog(#"started processing %#",videoUrl);
AVURLAsset* videoAsset = [[AVURLAsset alloc]initWithURL: videoUrl options:nil];
AVMutableComposition* mixComposition = [AVMutableComposition composition];
NSError * error = nil;
for (NSMutableDictionary * audioInfo in audioInfoArray){
// NSString *pathString = [[NSHomeDirectory() stringByAppendingString:#"/Documents/"] stringByAppendingString: [audioInfo objectForKey: #"fileName"]];
// NSString *pathString = [audioInfo objectForKey: #"filePath"];
NSURL *audioUrl=[audioInfo objectForKey: #"filePath"];
// NSLog(#"audioUrl %#",audioUrl);
AVURLAsset * urlAsset = [AVURLAsset URLAssetWithURL:audioUrl options:nil];
AVAssetTrack * audioAssetTrack = [[urlAsset tracksWithMediaType:AVMediaTypeAudio] objectAtIndex:0];
AVMutableCompositionTrack *compositionAudioTrack = [mixComposition addMutableTrackWithMediaType:AVMediaTypeAudio
preferredTrackID: kCMPersistentTrackID_Invalid];
// NSLog(#"%lf", [[audioInfo objectForKey: #"startTime"] doubleValue]);
CMTime audioStartTime = CMTimeMake(([[audioInfo objectForKey: #"startTime"] doubleValue]*TIME_SCALE), TIME_SCALE);
[compositionAudioTrack insertTimeRange:CMTimeRangeMake(kCMTimeZero,urlAsset.duration) ofTrack:audioAssetTrack atTime:audioStartTime error:&error];
}
AVMutableCompositionTrack *compositionVideoTrack = [mixComposition addMutableTrackWithMediaType:AVMediaTypeVideo
preferredTrackID:kCMPersistentTrackID_Invalid];
[compositionVideoTrack insertTimeRange:CMTimeRangeMake(kCMTimeZero, videoAsset.duration)
ofTrack:[[videoAsset tracksWithMediaType:AVMediaTypeVideo] objectAtIndex:0]
atTime:kCMTimeZero error:&error];
AVAssetExportSession* _assetExport = [[AVAssetExportSession alloc] initWithAsset:mixComposition
presetName:AVAssetExportPresetPassthrough];
NSString* videoName = #"export.mov";
NSString *exportPath = [[NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES) objectAtIndex:0] stringByAppendingPathComponent:videoName];
NSURL *exportUrl = [NSURL fileURLWithPath:exportPath];
if ([[NSFileManager defaultManager] fileExistsAtPath:exportPath])
{
[[NSFileManager defaultManager] removeItemAtPath:exportPath error:nil];
}
_assetExport.outputFileType = #"com.apple.quicktime-movie";
// _assetExport.outputFileType=AVFileTypeMPEG4;
NSLog(#"file type %#",_assetExport.outputFileType);
_assetExport.outputURL = exportUrl;
_assetExport.shouldOptimizeForNetworkUse = YES;
[_assetExport exportAsynchronouslyWithCompletionHandler:
^(void ) {
switch (_assetExport.status)
{
case AVAssetExportSessionStatusCompleted:
//export complete
NSLog(#"Export Complete");
//[self uploadToYouTube];
break;
case AVAssetExportSessionStatusFailed:
NSLog(#"Export Failed");
NSLog(#"ExportSessionError: %#", [_assetExport.error localizedDescription]);
//export error (see exportSession.error)
break;
case AVAssetExportSessionStatusCancelled:
NSLog(#"Export cancelled");
NSLog(#"ExportSessionError: %#", [_assetExport.error localizedDescription]);
//export cancelled
break;
}
}];
NSLog(#"completed processing exportPath %# ",exportPath);
return exportPath;
}
What is wrong with my code can you help me

Answer 1

What codec is the audio encoded with? As I understand it, if you are using some form of apple proprietary codec that could be causing your issues.