Combine two audio files into one in objective c [duplicate]

Answer 1

You can merge 2 mp3 files as:-

  NSMutableData *part1 = [NSMutableData dataWithContentsOfFile: [[NSBundle mainBundle] pathForResource:@"file1" ofType: @"mp3"]];

  NSMutableData *part2 = [NSMutableData dataWithContentsOfFile: [[NSBundle mainBundle] pathForResource:@"file2" ofType: @"mp3"]];

 [part1 appendData: part2];

 NSArray *paths = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES);
 NSString *documentsDir = [paths objectAtIndex:0];
    NSString *myMp3 = [documentsDir stringByAppendingPathComponent: @"final.mp3"];

    [part1 writeToFile:myMp3 atomically:YES];

This way you can straight away append mp3 file into one. I have used it in one of my apps. It gets a bit complicated for other formats where you have to update the header of the files respectively, but relatively simpler with mp3.

UPDATE:

Well you must also take care that the bit rates of the mp3 files you are trying to concatenate are same. If they differ they will merge but would play only partially or perhaps not at all. So make sure the bit rates sync with each other.

Answer 2

One alternative is to use AVAssetReader to convert all the mp3 files into uncompressed audio files, or even memory buffers if the audio is short enough. Uncompressed PCM data can then just be concatenated, mixed, or cross-faded, as needed. Then use AVAssetWriter to write the result into some compressed file format (such as aac) if needed.

Answer 3

Look at AVFoundation framework ... There're many ways, but the simplest one for you can be ...

• create AVAsset for both files (use AVURLAsset subclass),
• alloc AVMutableComposition (composition),
• add AVMutableCompositionTrack with type AVMediaTypeAudio to composition

[composition addMutableTrackWithMediaType:AVMediaTypeAudio preferredTrackID:kCMPersistentTrackID_Invalid];

• get track(s) from the first AVAsset and add it AVMutableCompositionTrack,
• get track(s) from the second AVAsset and append it to AVMutableCompositionTrack,
• then create AVAssetExportSession with your composition and export it.

Simplified description, but you get a clue. Depends on how many tracks do you have, what kind of effects do you want to use, etc.

If you do want to see some real code, open AVMovieExporter example, copy this code and remove video stuff and leave audio there only.