How to add audio to video file on iphone SDK - iphone

Question

I have a video file and an audio file. Is it possible to merge it to one video with with sound file. I think AVMutableComposition should help me, but I still dont understand how. any advices?

Answer 1

Thanks Daniel. I figured it out, its easy.
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, videoAsset.duration)
ofTrack:[[videoAsset tracksWithMediaType:AVMediaTypeVideo] objectAtIndex:0]
atTime:kCMTimeZero error:nil];
AVAssetExportSession* _assetExport = [[AVAssetExportSession alloc] initWithAsset:mixComposition
presetName:AVAssetExportPresetPassthrough];
NSString* videoName = #"export.mov";
NSString *exportPath = [NSTemporaryDirectory() stringByAppendingPathComponent:videoName];
NSURL *exportUrl = [NSURL fileURLWithPath:exportPath];
if ([[NSFileManager defaultManager] fileExistsAtPath:exportPath])
{
[[NSFileManager defaultManager] removeItemAtPath:exportPath error:nil];
}
_assetExport.outputFileType = #"com.apple.quicktime-movie";
DLog(#"file type %#",_assetExport.outputFileType);
_assetExport.outputURL = exportUrl;
_assetExport.shouldOptimizeForNetworkUse = YES;
[_assetExport exportAsynchronouslyWithCompletionHandler:
^(void ) {
// your completion code here
}
}
];

Answer 2

Yes it is possible, here is a snippet of code that is used to add audio to an existing composition, i grabbed this from apples sample code, you should probably view the whole project, youll find it very useful, the project is AVEditDemo and you can find it in the WWDC 2010 material that they posted here developer.apple.com/videos/wwdc/2010. Hope that helps
- (void)addCommentaryTrackToComposition:(AVMutableComposition *)composition withAudioMix:(AVMutableAudioMix *)audioMix
{
NSInteger i;
NSArray *tracksToDuck = [composition tracksWithMediaType:AVMediaTypeAudio]; // before we add the commentary
// Clip commentary duration to composition duration.
CMTimeRange commentaryTimeRange = CMTimeRangeMake(self.commentaryStartTime, self.commentary.duration);
if (CMTIME_COMPARE_INLINE(CMTimeRangeGetEnd(commentaryTimeRange), >, [composition duration]))
commentaryTimeRange.duration = CMTimeSubtract([composition duration], commentaryTimeRange.start);
// Add the commentary track.
AVMutableCompositionTrack *compositionCommentaryTrack = [composition addMutableTrackWithMediaType:AVMediaTypeAudio preferredTrackID:kCMPersistentTrackID_Invalid];
[compositionCommentaryTrack insertTimeRange:CMTimeRangeMake(kCMTimeZero, commentaryTimeRange.duration) ofTrack:[[self.commentary tracksWithMediaType:AVMediaTypeAudio] objectAtIndex:0] atTime:commentaryTimeRange.start error:nil];
NSMutableArray *trackMixArray = [NSMutableArray array];
CMTime rampDuration = CMTimeMake(1, 2); // half-second ramps
for (i = 0; i < [tracksToDuck count]; i++) {
AVMutableAudioMixInputParameters *trackMix = [AVMutableAudioMixInputParameters audioMixInputParametersWithTrack:[tracksToDuck objectAtIndex:i]];
[trackMix setVolumeRampFromStartVolume:1.0 toEndVolume:0.2 timeRange:CMTimeRangeMake(CMTimeSubtract(commentaryTimeRange.start, rampDuration), rampDuration)];
[trackMix setVolumeRampFromStartVolume:0.2 toEndVolume:1.0 timeRange:CMTimeRangeMake(CMTimeRangeGetEnd(commentaryTimeRange), rampDuration)];
[trackMixArray addObject:trackMix];
}
audioMix.inputParameters = trackMixArray;
}

Answer 3

Here is the swift version:
func mixAudio(audioURL audioURL: NSURL, videoURL: NSURL) {
let audioAsset = AVURLAsset(URL: audioURL)
let videoAsset = AVURLAsset(URL: videoURL)
let mixComposition = AVMutableComposition()
let compositionCommentaryTrack = mixComposition.addMutableTrackWithMediaType(AVMediaTypeAudio, preferredTrackID: kCMPersistentTrackID_Invalid)
// add audio
let timeRange = CMTimeRangeMake(kCMTimeZero, audioAsset.duration)
let track = audioAsset.tracksWithMediaType(AVMediaTypeAudio)[0]
do {
try compositionCommentaryTrack.insertTimeRange(timeRange, ofTrack: track, atTime: kCMTimeZero)
}
catch {
print("Error insertTimeRange for audio track \(error)")
}
// add video
let compositionVideoTrack = mixComposition.addMutableTrackWithMediaType(AVMediaTypeVideo, preferredTrackID: kCMPersistentTrackID_Invalid)
let timeRangeVideo = CMTimeRangeMake(kCMTimeZero, videoAsset.duration)
let trackVideo = videoAsset.tracksWithMediaType(AVMediaTypeVideo)[0]
do {
try compositionVideoTrack.insertTimeRange(timeRangeVideo, ofTrack: trackVideo, atTime: kCMTimeZero)
}
catch {
print("Error insertTimeRange for video track \(error)")
}
// export
let assetExportSession = AVAssetExportSession(asset: mixComposition, presetName: AVAssetExportPresetPassthrough)
let videoName = "export.mov"
exportPath = "\(NSTemporaryDirectory())/\(videoName)"
let exportURL = NSURL(fileURLWithPath: exportPath!)
if NSFileManager.defaultManager().fileExistsAtPath(exportPath!) {
do {
try NSFileManager.defaultManager().removeItemAtPath(exportPath!)
}
catch {
print("Error deleting export.mov: \(error)")
}
}
assetExportSession?.outputFileType = "com.apple.quicktime-movie"
assetExportSession?.outputURL = exportURL
assetExportSession?.shouldOptimizeForNetworkUse = true
assetExportSession?.exportAsynchronouslyWithCompletionHandler({
print("Mixed audio and video!")
dispatch_async(dispatch_get_main_queue(), {
print(self.exportPath!)
})
})
}