How to join (combine) multiple MP3 files in OS X

by Ross McKillop on April 24, 2007

Mac

This tutorial will guide you in joining two or more MP3 files together into one (longer) MP3 – using free, open source software.

Before we get started, it’s very much worth noting that if you have access to the .wav files, or the CD that you created the MP3s from, it’s best to use either of those sources to create your ‘combined’ MP3. When you join MP3 files together with Audacity, they are first decoded to a format that Audacity can work with, and then re-encoded back to MP3. This causes some loss in quality. The loss isn’t huge, but if you fancy yourself as an audiophile with a sharp ear, you might notice the difference between the original MP3 files and the “joined” one.

  1. Start by downloading and installing Audacity. You’ll also need the LAME library – download and unzip it (doesn’t matter where, just remember the location).
  2. Launch Audacity and select File and then Open…

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  4. Navigate to the MP3 (or WAV) files you want to combine. Select multiple files by holding down the Apple key, and then click Open. Each file will now be imported into Audacity.

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  6. Here’s where it gets just a tiny bit tricky. You’ll need to select one of the files to ‘paste’ into the other one. By default, when you paste one file into another, it’s put at the beginning. So, bring the track you want to play “first” in your final MP3 into the foreground. Click on the area in the bottom left part of the window (see the pink circle in the screenshot below). You’ll know you’ve done it right because the light gray background turns a darker shade of gray.

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  8. Now select Edit and then Cut

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  10. Bring the other Audacity window to the foreground, select Edit and then Paste

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  12. You should now have a screen similar to the image below – again, the track that you pasted will be at the beginning. You can use the Play button to hear how the entire ‘combined’ MP3 will sound.

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  14. Now it’s time to save the combined files into one. Select File and then Export As MP3…

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  16. Give your new MP3 a name and choose a location to save it. Click Save

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  18. At this point you’ll very likely be presented with a screen asking you to locate libmp3lame.dylib. Click Yes

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  20. Navigate to the folder that you created way back in step one. That folder contains the required libmp3lame.dylib file. Select it, then click Open.

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  22. If you’d like, you can enter the ID info now. Click OK when you’re ready.

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  24. Audacity will now encode and export your file. Depending on the speed of your Mac and the size/length of the MP3 files, this can take anywhere from a few seconds to.. hours?

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  26. That’s it. Give your newly created MP3 a listen to make sure it all went smoothly.
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  • http://www.tweako.com Mike

    Great explanation. I enjoy your tutorials. This one, among a few others, has been submitted into the queue @ tweako

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  • scate

    Although this is a handy tutorial, it is important to understand the clearly stated caveat that this workflow doesn’t just stitch the original mp3 files together. Instead, it decodes the mp3files, combines them and re-encodes the new, combined file as new mp3, resulting in generational loss.

    It is possible in many cases to actually join matching mp3 files with no conversion or generational loss if they are identically encoded. You can even do it in iTunes using a track splicing script from http://dougscripts.com/. There are also some stand alone utilities for mac and windows for this purpose.

  • http://smallstepsforward.com bt

    Ajoiner does this without all the headache. Or not as much headache.

  • http://ianbeatty.com/blog Ian

    I found I had to save, close, and re-open the Audacity project containing the two combined pieces, and *then* export, or something messed up and I ended up with a file long enough for both combined pieces, but with the audio for the second piece starting at the beginning, followed by silence for the duration of the first piece.

    Also, Audacity crashed repeatedly on me while trying to export to mp3, so I exported to WAV and used EasyWMA (fantastic program) to convert to mp3.

    (Audacity 1.2.5 on Mac OS X 10.5.2.)

  • Joletta

    Thank you so much for this painless tutorial. I didn’t have the foresight to check the additional links below so I adapted as I went (I’m running windows).

  • http://joelee.org Joe Lee

    Why all the fuss with Audacity? You can just open up Terminal and:

    cat *.mp3 > combined.mp3

  • andy

    ” cat *.mp3 > combined.mp3″
    Will make one very big file — either put combined in a different directory or change the extension.

    cat *.mp3 > combined.mp4 or cat *.mp3 > combined/combined.mp3

  • anthony

    Thanks man, this was super helpful! :)

  • Yadanar

    Thank you so much. :)

  • Oneball

    Thank you so much…It works!

  • portotalley

    i use iDealshare VideoGo to merge my MP3 files into one, it also helps me to combine WAV, M4A, WMA, AIFF, FLAC, OGG, and etc.