AAC and MP3 Files

Making AAC and MP3 Files with iTunes

AAC and MP3 are both lossy audio compression formats. AAC is the default format used by iTunes. It produces better audio quality than MP3 for a given data rate (e.g., 128 kbps) and is playable in almost all software that can play MP3 files.

CAUTION: If your music contains sounds copyrighted by other people, and you don’t have permission to use those sounds, then think twice about uploading your music to a web site. That counts as distribution, and the copyright holder may hold you accountable for your use of their sound.

Exporting a Mix File from Reason

Before making an AAC or MP3 file, you first must export your mix as an uncompressed audio file, either Wave or AIFF.

  1. First, be sure that your mix never clips, and that you have left at least 1.5 dB of headroom. If you don’t know what this means, please review The Limiter, including the advice at the end of that section about the headroom required before encoding compressed audio files.
  2. Set the Song End Marker to the actual end of the sound that your sequence makes, taking into account any reverberation or delay ringoff. If you don’t do this, you may end up with lots of silence at the end of your mix file.

    Reason sequencer end marker when off-screen

    To find the End marker, look at the right side of the sequence horizontal scroll bar for the vertical symbol circled in red below.

    Scroll this part of the sequence into view until you can see the End marker in the time ruler: the small box enclosing E.

    Reason sequencer end marker when on-screen

    Drag this marker to the point where you no longer hear any sound sustaining from your last notes, such as delay or reverb tails. Please leave 2-3 seconds of silence before the End marker.

  3. Choose File > Export Song as Audio File, select either an AIFF or Wave file (doesn’t matter which), and click the Export button in the Audio Export Settings window that appears. The default settings (44,100 Hz sampling rate, 16 bits, and dither) are fine.
  4. Listen to your mix file to be sure that it sounds like what you expect, and that the ending does not cut off a reverb tail. Be sure the file does not contain more than 5 seconds of silence at the end. If it does, see step 1.

Making an AAC File

Here’s how to make an AAC file using the iTunes program available on the M373 Macs. (These instructions are correct as of iTunes

  1. Type “iTunes” into the Spotlight search box at the top-right corner of the screen (by clicking the magnifying glass icon).

    Because of the way iTunes is set up in our room, this often will present you with an annoying series of choices. Just agree to the license, and say “No Thanks” to the offer to share your library details with Apple.

  2. Click on the Songs category in the list at the left side of the iTunes window. If you don’t do this, you will be lost below.
  3. Drag the AIFF or Wave mix file, which you made in Reason, from the Finder (e.g., Desktop) into the main (right) part of the iTunes window. (If you double-clicked your mix file earlier to listen to it, it probably is already open in iTunes.)
  4. Click on the file to select it.
  5. Choose the File > Convert > Create AAC Version menu command.

    Soon a new file will appear, with the same name as your mix file. So how do you know which is which? Right-click on the column headings strip, which gives the name, time, artist, etc. Choose Bit Rate from the list of column names. Your mix file will have a 1,411 kbps bit rate (or 2,116 kbps, if your mix file is 24 bit), while the AAC file will be 256 kbps.

  6. Enter metadata, such as the song title and composer, into your file. To do this, select your new AAC file in iTunes, and choose Edit > Song Info. Fill out at least the song and artist fields.
  7. Drag this new file from the iTunes window onto the Desktop. Verify that this is an AAC file: select the file, and choose File > Get Info. In the General section of the info window, its Kind should be Apple MPEG-4 audio. If your Finder is set to show file extensions, the extension for an AAC file is “.m4a”. If none of this looks right, you may have dragged the wrong file from iTunes.

    If for some reason dragging the file doesn’t work, right-click on it in iTunes, and choose Show in Finder. This will show you a Finder window for the folder that contains both your files (e.g., the Wave and the AAC).

Making an MP3 File

If you want to make an MP3 file instead of an AAC file, insert these steps between steps 3 and 4 above. Bear in mind that AAC is higher quality than MP3, for equivalent data rates, and is widely supported in software now.

  1. Choose Preferences from the iTunes menu, and click the General icon.
  2. Click the Import Settings button. Choose MP3 Encoder in the Import Using pop-up menu.
  3. The Setting menu lets you control the quality (and therefore size) of the MP3s you make. Choose 192 kbps.
  4. Press OK twice to confirm the Import Settings and Preferences dialogs.

    When you choose the Convert command, mentioned above, it will be called Create MP3 Version.