Concat two audio files (one after another) in iOS

Question

I want to concatenate two audio files into one. I had done following code. Please check below.

- (BOOL)combineFiles{
    AVMutableComposition *composition = [[AVMutableComposition alloc] init];

    AVMutableCompositionTrack *compositionAudioTrack = [composition addMutableTrackWithMediaType:AVMediaTypeAudio preferredTrackID:kCMPersistentTrackID_Invalid];
    [compositionAudioTrack setPreferredVolume:0.8];
    NSString *soundOne  =[[NSBundle mainBundle]pathForResource:@"test1" ofType:@"m4a"];
    NSURL *url = [NSURL fileURLWithPath:soundOne];
    AVAsset *avAsset = [AVURLAsset URLAssetWithURL:url options:nil];
    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];
    [compositionAudioTrack1 setPreferredVolume:0.8];
    NSString *soundOne1  =[[NSBundle mainBundle]pathForResource:@"test2" ofType:@"m4a"];
    NSURL *url1 = [NSURL fileURLWithPath:soundOne1];
    AVAsset *avAsset1 = [AVURLAsset URLAssetWithURL:url1 options:nil];
    AVAssetTrack *clipAudioTrack1 = [[avAsset1 tracksWithMediaType:AVMediaTypeAudio] objectAtIndex:0];
    [compositionAudioTrack1 insertTimeRange:CMTimeRangeMake(kCMTimeZero, avAsset.duration) ofTrack:clipAudioTrack1 atTime:kCMTimeZero error:nil];

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

    exportSession.outputURL = [NSURL fileURLWithPath:[@"test3.m4a" documentDirectory]]; // output path
    exportSession.outputFileType = AVFileTypeAppleM4A; // output file type

    // perform the export
    [exportSession exportAsynchronouslyWithCompletionHandler:^{
        if (AVAssetExportSessionStatusCompleted == exportSession.status) {
            NSLog(@"AVAssetExportSessionStatusCompleted");
        } else if (AVAssetExportSessionStatusFailed == exportSession.status) {
            NSLog(@"AVAssetExportSessionStatusFailed");
        } else {
            NSLog(@"Export Session Status: %ld", (long)exportSession.status);
        }
    }];
    return YES;
}

From above code we can combine two audio files into one, where both files play simultaneously. But I want the third file to play the first two files one after the other.

Please help me to solve this problem.

Answer 1

After doing much research I found answer.. It works..

- (void)mergeTwoAudioFiles{
    AVAsset *avAsset1 = [AVURLAsset URLAssetWithURL:[NSURL fileURLWithPath:[[NSBundle mainBundle] pathForResource:@"test1" ofType:@"m4a"]] options:nil];
    AVAsset *avAsset2 = [AVURLAsset URLAssetWithURL:[NSURL fileURLWithPath:[[NSBundle mainBundle] pathForResource:@"test2" ofType:@"m4a"]] options:nil];

    AVMutableComposition *composition = [[AVMutableComposition alloc] init];
    [composition addMutableTrackWithMediaType:AVMediaTypeAudio preferredTrackID:kCMPersistentTrackID_Invalid];

    AVMutableCompositionTrack *track = [composition addMutableTrackWithMediaType:AVMediaTypeAudio preferredTrackID:kCMPersistentTrackID_Invalid];
    AVAssetTrack *assetTrack1 = [[avAsset1 tracksWithMediaType:AVMediaTypeAudio] objectAtIndex:0];
    AVAssetTrack *assetTrack2 = [[avAsset2 tracksWithMediaType:AVMediaTypeAudio] objectAtIndex:0];

    CMTime insertionPoint = kCMTimeZero;
    [track insertTimeRange:CMTimeRangeMake(kCMTimeZero, avAsset1.duration) ofTrack:assetTrack1 atTime:insertionPoint error:nil];
    insertionPoint = CMTimeAdd(insertionPoint, avAsset1.duration);
    [track insertTimeRange:CMTimeRangeMake(kCMTimeZero, avAsset2.duration) ofTrack:assetTrack2 atTime:insertionPoint error:nil];

    AVAssetExportSession *exportSession = [AVAssetExportSession exportSessionWithAsset:composition presetName:AVAssetExportPresetAppleM4A];
    exportSession.outputURL = [NSURL fileURLWithPath:[@"test3.m4a" documentDirectory]];
    exportSession.outputFileType = AVFileTypeAppleM4A;

    [exportSession exportAsynchronouslyWithCompletionHandler:^{
        if (AVAssetExportSessionStatusCompleted == exportSession.status) {
            NSLog(@"AVAssetExportSessionStatusCompleted");
        } else if (AVAssetExportSessionStatusFailed == exportSession.status) {
            NSLog(@"AVAssetExportSessionStatusFailed");
        } else {
            NSLog(@"Export Session Status: %ld", (long)exportSession.status);
        }
    }];
}

Answer 2

I've worked on a similar project before, and I'm pulling out this code from there. In that project I concatenate between 1 and 160 sounds one after another, and this code works.

AVMutableComposition *composition = [AVMutableComposition composition];
NSMutableArray* audioMixParams = [[NSMutableArray alloc] init]; //Audio mixing parameters
AVMutableCompositionTrack *track = [composition addMutableTrackWithMediaType:AVMediaTypeAudio preferredTrackID:kCMPersistentTrackID_Invalid]; //you can choose your file format here, I chose mp3
[self setUpAndAddAudioAtPath:[NSURL fileURLWithPath:[[NSBundle mainBundle] pathForResource:test1 ofType:@"m4a"]] toComposition:composition atStartTime:[composition duration];
[self setUpAndAddAudioAtPath:[NSURL fileURLWithPath:[[NSBundle mainBundle] pathForResource:test2 ofType:@"m4a"]] toComposition:composition atStartTime:[composition duration];
AVMutableAudioMixInputParameters *trackMix = [AVMutableAudioMixInputParameters audioMixInputParametersWithTrack:track];
[trackMix setVolume:0.8f atTime:CMTimeMake(0, 1)];
[audioMixParams addObject:trackMix];
AVMutableAudioMix *audioMix = [AVMutableAudioMix audioMix];
audioMix.inputParameters = [NSArray arrayWithArray:audioMixParams];
NSLog (@"compatible presets for songAsset: %@",
           [AVAssetExportSession exportPresetsCompatibleWithAsset:composition]);

AVAssetExportSession *exporter = [[AVAssetExportSession alloc]
                                  initWithAsset: composition
                                  presetName: AVAssetExportPresetAppleM4A];
exporter.audioMix = audioMix;
exporter.outputFileType = @"com.apple.m4a-audio";

NSURL *exportURL = [NSURL fileURLWithPath:[NSString stringWithFormat:@"%@/test.m4a",docDir]];
NSFileManager *fileManager = [NSFileManager defaultManager];
[fileManager removeItemAtPath:[docDir stringByAppendingPathComponent:@"test.m4a"] error:NULL];
exporter.outputURL = exportURL;
[exporter exportAsynchronouslyWithCompletionHandler:^{
        int exportStatus = exporter.status;
        switch (exportStatus) {
            case AVAssetExportSessionStatusFailed:
                NSLog(@"AVAssetExportSessionStatusFailed");
                break;

            case AVAssetExportSessionStatusCompleted: {
                NSLog (@"AVAssetExportSessionStatusCompleted");
                break;
            }
            case AVAssetExportSessionStatusUnknown: NSLog (@"AVAssetExportSessionStatusUnknown"); break;
            case AVAssetExportSessionStatusExporting: {
                dispatch_async(dispatch_get_main_queue(), ^{

                });
                NSLog (@"AVAssetExportSessionStatusExporting");
                break;
            }
            case AVAssetExportSessionStatusCancelled: NSLog (@"AVAssetExportSessionStatusCancelled"); break;
            case AVAssetExportSessionStatusWaiting: NSLog (@"AVAssetExportSessionStatusWaiting"); break;
            default:  NSLog (@"didn't get export status"); break;
        }
    }];

I wrote a special function to add track at given position, given below:

- (void) setUpAndAddAudioAtPath:(NSURL*)assetURL toComposition:(AVMutableComposition *)composition atStartTime: (CMTime) startTime{
    AVURLAsset *songAsset = [AVURLAsset URLAssetWithURL:assetURL options:nil];
    CMTime trackDuration = songAsset.duration;
    AVMutableCompositionTrack *track = [composition addMutableTrackWithMediaType:AVMediaTypeAudio preferredTrackID:kCMPersistentTrackID_Invalid];
    AVAssetTrack *sourceAudioTrack = [[songAsset tracksWithMediaType:AVMediaTypeAudio] objectAtIndex:0];

    NSError *error = nil;
    BOOL ok = NO;

    //CMTime longestTime = CMTimeMake(848896, 44100); //(19.24 seconds)
    CMTimeRange tRange = CMTimeRangeMake(CMTimeMake(0, 1), trackDuration);
    //NSLog(@"Note Duration = %f", CMTimeGetSeconds(trackDuration));
    //Set Volume
    AVMutableAudioMixInputParameters *trackMix = [AVMutableAudioMixInputParameters audioMixInputParametersWithTrack:track];
    [trackMix setVolume:0.8f atTime:startTime];
    [self.audioMixParams addObject:trackMix];

    //Insert audio into track
    ok = [track insertTimeRange:tRange ofTrack:sourceAudioTrack atTime:startTime error:&error];
    //NSLog(@"%d",ok);
}

This code worked for me, AS-IS. Please let me know if this helps.