How to concatenate 2 or 3 audio files in iOS?

Question

I am newcomer in Objective-C and have experience only 5 months in iPhone development.

What I need:
I need to concatenate 2 or more audio files into one, and export result as aiff, mp3, caf or m4a format.

For example:
First audio file containing "You need", second "download" and third "document".
Every audio part depends on actions from user.

I spent 2 days without luck. That place is my last frontier.

I will very appreciate for a piece of code.

Answer 1

You can use this method to merge 3 sounds together.

- (BOOL) combineVoices1
{
    NSError *error = nil;
    BOOL ok = NO;


    NSArray *paths = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory,    NSUserDomainMask, YES);
    NSString *documentsDirectory = [paths objectAtIndex:0];


    CMTime nextClipStartTime = kCMTimeZero;
    //Create AVMutableComposition Object.This object will hold our multiple AVMutableCompositionTrack.
    AVMutableComposition *composition = [[AVMutableComposition alloc] init];

    AVMutableCompositionTrack *compositionAudioTrack = [composition addMutableTrackWithMediaType:AVMediaTypeAudio preferredTrackID:kCMPersistentTrackID_Invalid];
    [compositionAudioTrack setPreferredVolume:0.8];
    NSString *soundOne  =[[NSBundle mainBundle]pathForResource:@"test1" ofType:@"caf"];
    NSURL *url = [NSURL fileURLWithPath:soundOne];
    AVAsset *avAsset = [AVURLAsset URLAssetWithURL:url options:nil];
    NSArray *tracks = [avAsset tracksWithMediaType:AVMediaTypeAudio];
    AVAssetTrack *clipAudioTrack = [[avAsset tracksWithMediaType:AVMediaTypeAudio] objectAtIndex:0];
    [compositionAudioTrack insertTimeRange:CMTimeRangeMake(kCMTimeZero, avAsset.duration) ofTrack:clipAudioTrack atTime:kCMTimeZero error:nil];

    AVMutableCompositionTrack *compositionAudioTrack1 = [composition addMutableTrackWithMediaType:AVMediaTypeAudio preferredTrackID:kCMPersistentTrackID_Invalid];
    [compositionAudioTrack setPreferredVolume:0.3];
    NSString *soundOne1  =[[NSBundle mainBundle]pathForResource:@"test" ofType:@"caf"];
    NSURL *url1 = [NSURL fileURLWithPath:soundOne1];
    AVAsset *avAsset1 = [AVURLAsset URLAssetWithURL:url1 options:nil];
    NSArray *tracks1 = [avAsset1 tracksWithMediaType:AVMediaTypeAudio];
    AVAssetTrack *clipAudioTrack1 = [[avAsset1 tracksWithMediaType:AVMediaTypeAudio] objectAtIndex:0];
    [compositionAudioTrack1 insertTimeRange:CMTimeRangeMake(kCMTimeZero, avAsset.duration) ofTrack:clipAudioTrack1 atTime:kCMTimeZero error:nil];


    AVMutableCompositionTrack *compositionAudioTrack2 = [composition addMutableTrackWithMediaType:AVMediaTypeAudio preferredTrackID:kCMPersistentTrackID_Invalid];
    [compositionAudioTrack2 setPreferredVolume:1.0];
    NSString *soundOne2  =[[NSBundle mainBundle]pathForResource:@"song" ofType:@"caf"];
    NSURL *url2 = [NSURL fileURLWithPath:soundOne2];
    AVAsset *avAsset2 = [AVURLAsset URLAssetWithURL:url2 options:nil];
    NSArray *tracks2 = [avAsset2 tracksWithMediaType:AVMediaTypeAudio];
    AVAssetTrack *clipAudioTrack2 = [[avAsset2 tracksWithMediaType:AVMediaTypeAudio] objectAtIndex:0];
    [compositionAudioTrack1 insertTimeRange:CMTimeRangeMake(kCMTimeZero, avAsset2.duration) ofTrack:clipAudioTrack2 atTime:kCMTimeZero error:nil];



    AVAssetExportSession *exportSession = [AVAssetExportSession
                                           exportSessionWithAsset:composition
                                           presetName:AVAssetExportPresetAppleM4A];
    if (nil == exportSession) return NO;

    NSString *soundOneNew = [documentsDirectory stringByAppendingPathComponent:@"combined10.m4a"];
    //NSLog(@"Output file path - %@",soundOneNew);

    // configure export session  output with all our parameters
    exportSession.outputURL = [NSURL fileURLWithPath:soundOneNew]; // output path
    exportSession.outputFileType = AVFileTypeAppleM4A; // output file type

    // perform the export
    [exportSession exportAsynchronouslyWithCompletionHandler:^{

        if (AVAssetExportSessionStatusCompleted == exportSession.status) {
            NSLog(@"AVAssetExportSessionStatusCompleted");
        } else if (AVAssetExportSessionStatusFailed == exportSession.status) {
            // a failure may happen because of an event out of your control
            // for example, an interruption like a phone call comming in
            // make sure and handle this case appropriately
            NSLog(@"AVAssetExportSessionStatusFailed");
        } else {
            NSLog(@"Export Session Status: %d", exportSession.status);
        }
    }];


    return YES;


}

Answer 2

The easiest way to implement multiple combinations of aac：

- (NSString *)concatenatedAACVoicesPath{
NSMutableData *concatenatedData = [[NSMutableData alloc] init];

NSArray *aacPathArr = [self queryAAC];
for (NSString *path in aacPathArr) {
    NSData *data = [[NSData alloc] initWithContentsOfFile:path];
    [concatenatedData appendData: data];
}

NSString *fileNamePath = [NSString stringWithFormat:@"%@/%@.aac",[NSString createPath:currRecordDocName],currRecordDocName];
[concatenatedData writeToFile:fileNamePath atomically:YES];

return fileNamePath;

}

Answer 3

You should probably look into this post for doing the same: Combine two audio files into one in objective c

The answer is similar to what Dimitar has suggested. But 2 important things that you have to keep in mind are that, first - it works only for mp3 format and second the bit-rate of all the files that you are trying to concatenate should be same, or else only parts of your file would play in the final output. It would stop playing where the bit rate changes.

SSteve- Files like Wav files have their own headers and if you just write one file after another, It would play just the first file and would then stop playing, inspite that the file info showing a greater file size. this is because we do not have information updated into the header of the first file.

Answer 4

I have taken two diffrent mp3 files from AVMutableCompositionTrack. and these two mp3 files are stored in same AVMutableComposition.

when i will press the button the path of new mp3 will be shown by console.

-(IBAction)play
{
    [self mixAudio];    
}

-(void)mixAudio
 {
    CFAbsoluteTime currentTime=CFAbsoluteTimeGetCurrent();
    AVMutableComposition *composition = [[AVMutableComposition alloc] init];

    AVMutableCompositionTrack *compositionAudioTrack = [composition addMutableTrackWithMediaType:AVMediaTypeAudio preferredTrackID:kCMPersistentTrackID_Invalid];
    [compositionAudioTrack setPreferredVolume:0.8];
    NSString *soundOne  =[[NSBundle mainBundle]pathForResource:@"KICK1" ofType:@"mp3"];
    NSURL *url = [NSURL fileURLWithPath:soundOne];
    AVAsset *avAsset = [AVURLAsset URLAssetWithURL:url options:nil];
    NSArray *tracks = [avAsset tracksWithMediaType:AVMediaTypeAudio];
    AVAssetTrack *clipAudioTrack = [tracks objectAtIndex:0];
    [compositionAudioTrack insertTimeRange:CMTimeRangeMake(kCMTimeZero, avAsset.duration) ofTrack:clipAudioTrack atTime:kCMTimeZero error:nil];

    AVMutableCompositionTrack *compositionAudioTrack1 = [composition addMutableTrackWithMediaType:AVMediaTypeAudio preferredTrackID:kCMPersistentTrackID_Invalid];
    [compositionAudioTrack setPreferredVolume:0.8];
    NSString *soundOne1  =[[NSBundle mainBundle]pathForResource:@"KICK2" ofType:@"mp3"];
    NSURL *url1 = [NSURL fileURLWithPath:soundOne1];
    AVAsset *avAsset1 = [AVURLAsset URLAssetWithURL:url1 options:nil];
    NSArray *tracks1 = [avAsset1 tracksWithMediaType:AVMediaTypeAudio];
    AVAssetTrack *clipAudioTrack1 = [tracks1 objectAtIndex:0];
    [compositionAudioTrack1 insertTimeRange:CMTimeRangeMake(kCMTimeZero, avAsset1.duration) ofTrack:clipAudioTrack1 atTime: kCMTimeZero error:nil];

    NSArray *paths = NSSearchPathForDirectoriesInDomains(NSLibraryDirectory, NSUserDomainMask, YES);
    NSString *libraryCachesDirectory = [paths objectAtIndex:0];
    NSString *strOutputFilePath = [libraryCachesDirectory stringByAppendingPathComponent:@"output.mov"];
    NSString *requiredOutputPath = [libraryCachesDirectory stringByAppendingPathComponent:@"output.m4a"];
    NSURL *audioFileOutput = [NSURL fileURLWithPath:requiredOutputPath];
    [[NSFileManager defaultManager] removeItemAtURL:audioFileOutput error:NULL];

    AVAssetExportSession *exporter=[[AVAssetExportSession alloc] initWithAsset:composition presetName:AVAssetExportPresetAppleM4A];
    exporter.outputURL=audioFileOutput;
    exporter.outputFileType=AVFileTypeAppleM4A;

    [exporter exportAsynchronouslyWithCompletionHandler:^{

        NSLog(@" OUtput path is \n %@", requiredOutputPath);
        NSFileManager * fm = [[NSFileManager alloc] init];
        [fm moveItemAtPath:strOutputFilePath toPath:requiredOutputPath error:nil];

         NSLog(@" OUtput path is \n %@", requiredOutputPath);
        NSLog(@"export complete: %lf",CFAbsoluteTimeGetCurrent()-currentTime);
        NSError *error;
        audioPlayer=[[AVAudioPlayer alloc]initWithContentsOfURL:audioFileOutput error:&error];
        audioPlayer.numberOfLoops=0;
        [audioPlayer play];

    }];

}

Answer 5

Have you tried something like this:

AudioFileCreateWithURL //to create the output file
For each input file:
    AudioFileOpenURL //open file
    repeat
        AudioFileReadBytes //read from input file
        AudioFileWriteBytes //write to output file
    until eof(input file)
    AudioFileClose //close input file
AudioFileClose //close output file

This would probably require that the input files are all the same format and would create the output file in that same format. If you need to convert the format, that might be better done after creating the output file.

Answer 6

I have an idea, not sure it will work. Try to get NSData from these 3 files, append the data into another NSData and then write it. Something like:

NSMutableData *concatenatedData = [NSMutableData alloc] init];
NSData *data1 = [[NSData alloc] initWithContentsOfFile:(NSString *)path];
NSData *data2 = [[NSData alloc] initWithContentsOfFile:(NSString *)path];
NSData *data3 = [[NSData alloc] initWithContentsOfFile:(NSString *)path];
[concatenatedData appendData: data1];
[concatenatedData appendData: data2];
[concatenatedData appendData: data3];
[concatenatedData writeToFile:@"/path/to/concatenatedData.mp3" atomically:YES];

It's a theory I'm not sure it will work :), it actually works if i open an mp3 with hex editor - copy everything and paste it in the end - then I have the same sound twice. Please try it and let us know if it works.