Create Movie Using AVFoundation

Steps to Create Movie Using AVFoundation:-

1. Create a AVMutableComposition

CFAbsoluteTime currentTime = CFAbsoluteTimeGetCurrent(); //Debug purpose - used to calculate the total time taken

NSError *error = nil;

AVMutableComposition *saveComposition = [AVMutableComposition composition];

2. Get the video and audio file path

NSString *tempPath = NSTemporaryDirectory();

NSString *videoPath = nil ;//<Video file path>;

NSString *audioPath = nil ;//<Audio file path>;;

3. Create the video asset 

NSURL * url1 = [[NSURL alloc] initFileURLWithPath:videoPath];

AVURLAsset *video = [AVURLAsset URLAssetWithURL:url1 options:nil];

[url1 release];

4. Get the AVMutableCompositionTrack for video and add the video track to it.

The method insertTimeRange: ofTrack: atTime: decides the what portion of the video to be added and also where the video track should appear in the final video created.

AVMutableCompositionTrack *compositionVideoTrack = [ addMutableTrackWithMediaType:AVMediaTypeVideo preferredTrackID:kCMPersistentTrackID_Invalid];

AVAssetTrack *clipVideoTrack = [[video tracksWithMediaType:AVMediaTypeVideo] objectAtIndex:0];

[compositionVideoTrack insertTimeRange:CMTimeRangeMake(kCMTimeZero, [video duration])  ofTrack:clipVideoTrack atTime:kCMTimeZero error:nil];

NSLog(@"%f %@",CMTimeGetSeconds([video duration]),error);

5. Create the Audio asset 

NSURL * url2 = [[NSURL alloc] initFileURLWithPath:audioPath];

AVURLAsset *audio = [AVURLAsset URLAssetWithURL:url2 options:nil];

[url2 release];

6. Get the AVMutableCompositionTrack for audio and add the audio track to it.

AVMutableCompositionTrack *compositionAudioTrack = [saveComposition addMutableTrackWithMediaType:AVMediaTypeAudio preferredTrackID:kCMPersistentTrackID_Invalid];

AVAssetTrack *clipAudioTrack = [[audio tracksWithMediaType:AVMediaTypeAudio] objectAtIndex:0];

[compositionAudioTrack insertTimeRange:CMTimeRangeMake(kCMTimeZero, [audio duration])  ofTrack:clipAudioTrack atTime:kCMTimeZero error:nil];

NSLog(@"%f %@",CMTimeGetSeconds([audio duration]),error);

7. Get file path for of the final video.

NSString *path = [tempPath stringByAppendingPathComponent:@"mergedvideo.mov"];

if([[NSFileManager defaultManager] fileExistsAtPath:path])

{

[[NSFileManager defaultManager] removeItemAtPath:path error:nil];

}

NSURL *url = [[NSURL alloc] initFileURLWithPath: path];

8. Create the AVAssetExportSession and set the preset to it.

The completion handler will be called upon the completion of the export.

AVAssetExportSession *exporter = [[[AVAssetExportSession alloc] initWithAsset:saveComposition presetName:AVAssetExportPresetHighestQuality] autorelease];

exporter.outputURL=url;

exporter.outputFileType=[[exporter supportedFileTypes] objectAtIndex:0];

[exporter exportAsynchronouslyWithCompletionHandler:^{

NSLog(@"export completed : %lf",CFAbsoluteTimeGetCurrent()-currentTime);

}];

The above technique can be used to merge N number of video and audio tracks and create a movie. I hope this tutorial helps to create movie using AVFoundation.