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.
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.
- 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.
- 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.
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.
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.
- 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.
- 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 220.127.116.11.)
- 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
- 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.
- 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.)
- Click on the file to select it.
- 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
- 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.
- 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.
- Choose Preferences from the iTunes menu, and click the
- Click the Import Settings button. Choose MP3 Encoder in
the Import Using pop-up menu.
- The Setting menu lets you control the quality (and therefore size)
of the MP3s you make. Choose 192 kbps.
- Press OK twice to confirm the Import Settings and Preferences
When you choose the Convert command, mentioned above, it will be
called Create MP3 Version.