Merging Audio with Video Objective-C - iphone

Question

I'm attempting to merge an audio file with a video file using:
+ (void)CompileFilesToMakeMovie:(NSString *) audioPath {
NSLog(#"a");
AVMutableComposition* mixComposition = [AVMutableComposition composition];
NSURL *audio_inputFileUrl = [[NSURL alloc] initFileURLWithPath:audioPath];
NSString *videoPath = [[NSBundle bundleForClass:[self class]] pathForResource:#"input" ofType:#"mov"];
NSURL* video_inputFileUrl = [NSURL fileURLWithPath:videoPath];
NSArray *dirPaths = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES);
NSString *docsDir = [dirPaths objectAtIndex:0];
NSString *outputFilePath = [docsDir stringByAppendingPathComponent:#"OutputFile.mov"];
NSURL* outputFileUrl = [NSURL fileURLWithPath:outputFilePath];
if ([[NSFileManager defaultManager] fileExistsAtPath:outputFilePath])
[[NSFileManager defaultManager] removeItemAtPath:outputFilePath error:nil];
NSLog(#"b");
CMTime nextClipStartTime = kCMTimeZero;
AVURLAsset* videoAsset = [[AVURLAsset alloc]initWithURL:video_inputFileUrl options:nil];
CMTimeRange video_timeRange = CMTimeRangeMake(kCMTimeZero,videoAsset.duration);
AVMutableCompositionTrack *a_compositionVideoTrack = [mixComposition addMutableTrackWithMediaType:AVMediaTypeVideo preferredTrackID:kCMPersistentTrackID_Invalid];
[a_compositionVideoTrack insertTimeRange:video_timeRange ofTrack:[[videoAsset tracksWithMediaType:AVMediaTypeVideo] objectAtIndex:0] atTime:nextClipStartTime error:nil];
NSLog(#"c");
AVURLAsset* audioAsset = [[AVURLAsset alloc]initWithURL:audio_inputFileUrl options:nil];
CMTimeRange audio_timeRange = CMTimeRangeMake(kCMTimeZero, audioAsset.duration);
AVMutableCompositionTrack *b_compositionAudioTrack = [mixComposition addMutableTrackWithMediaType:AVMediaTypeAudio preferredTrackID:kCMPersistentTrackID_Invalid];
[b_compositionAudioTrack insertTimeRange:audio_timeRange ofTrack:[[audioAsset tracksWithMediaType:AVMediaTypeAudio] objectAtIndex:0] atTime:nextClipStartTime error:nil];
NSLog(#"d");
AVAssetExportSession* _assetExport = [[AVAssetExportSession alloc] initWithAsset:mixComposition presetName:AVAssetExportPresetHighestQuality];
_assetExport.outputFileType = #"com.apple.quicktime-movie";
_assetExport.outputURL = outputFileUrl;
[_assetExport exportAsynchronouslyWithCompletionHandler:
^(void ) {
UISaveVideoAtPathToSavedPhotosAlbum(outputFilePath, nil, nil, nil);
}
];
}
But I am getting an error after "c" is logged for 'NSRangeException', reason:
* -[__NSArrayM objectAtIndex:]: index 0 beyond bounds for empty
array'.
The audio file is located at
NSArray *dirPaths = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES);
NSString *docsDir = [dirPaths objectAtIndex:0];
NSString *soundFilePath = [docsDir stringByAppendingPathComponent:#"%1.iaff"];
Any tips?
Thanks.

Answer 1

First of all I should say the audio format you have given is incorrect,
NSString *soundFilePath = [docsDir stringByAppendingPathComponent:#"%1.iaff"];
make that aiff NSString *soundFilePath = [docsDir stringByAppendingPathComponent:#"1.aiff"];
If you are not sure of the code you used,
This code works for me,
-(void) mergeAudio:(NSURL *) audioURL withVideo:(NSURL *) videoURL andSaveToPathUrl:(NSString *) savePath{
AVURLAsset* audioAsset = [[AVURLAsset alloc]initWithURL:audioURL options:nil];
AVURLAsset* videoAsset = [[AVURLAsset alloc]initWithURL:videoURL options:nil];
AVMutableComposition* mixComposition = [AVMutableComposition composition];
AVMutableCompositionTrack *compositionCommentaryTrack = [mixComposition addMutableTrackWithMediaType:AVMediaTypeAudio
preferredTrackID:kCMPersistentTrackID_Invalid];
[compositionCommentaryTrack insertTimeRange:CMTimeRangeMake(kCMTimeZero, audioAsset.duration)
ofTrack:[[audioAsset tracksWithMediaType:AVMediaTypeAudio] objectAtIndex:0]
atTime:kCMTimeZero error:nil];
AVMutableCompositionTrack *compositionVideoTrack = [mixComposition addMutableTrackWithMediaType:AVMediaTypeVideo
preferredTrackID:kCMPersistentTrackID_Invalid];
[compositionVideoTrack insertTimeRange:CMTimeRangeMake(kCMTimeZero, audioAsset.duration)
ofTrack:[[videoAsset tracksWithMediaType:AVMediaTypeVideo] objectAtIndex:0]
atTime:kCMTimeZero error:nil];
AVAssetExportSession* _assetExport = [[AVAssetExportSession alloc] initWithAsset:mixComposition
presetName:AVAssetExportPresetPassthrough];
NSURL *savetUrl = [NSURL fileURLWithPath:savePath];
if ([[NSFileManager defaultManager] fileExistsAtPath:savePath])
{
[[NSFileManager defaultManager] removeItemAtPath:savePath error:nil];
}
_assetExport.outputFileType = #"com.apple.quicktime-movie";
_assetExport.outputURL = savetUrl;
_assetExport.shouldOptimizeForNetworkUse = YES;
[_assetExport exportAsynchronouslyWithCompletionHandler:
^(void ) {
NSLog(#"fileSaved !");
}
];
}
Pass the videoURL, audioURL and save path of the final file

Answer 2

This is happening because the audio or the video file has yet not been completely written and you are trying to merge them. Make sure you use completion handlers to make sure audio and video file at the specific path is written completely.