Easily convert audio files to MP3 on Mac OSX
One minor Reason gripe is that it only exports audio files as AIFF or WAV, but not MP3. For distribution, this is probably what you want, but sometimes you want to create a small MP3 file to share with friends, etc.
I haven’t been able to figure out a way to export directly to MP3, but thankfully it’s fairly easy to set up an Automator workflow on OSX that allows you to conveniently convert any audio file to MP3 by right-clicking it in the Finder.
lame
The main thing you need is lame, an open source MP3 encoder. It is only officially released in source form, but there are several ways to obtain binaries for OSX.
Personally, I’m using Homebrew, which provides a convenient way to install many open source packages. Once Homebrew is installed, installing lame is as simple as running brew install lame in the Terminal. MacPorts is a similar alternative package manager.
If you prefer a traditional installer, it looks like you can obtain this from Thalictrum (although their latest version is about a year old: 3.98.4; the latest lame version at this time is 3.99.3). But lame has been stable for a long time, so in reality this probably doesn’t matter.
Automator
The next (and final) step is to set up an Automator workflow:
- Launch Automator
- Select “New” in the “File” menu
- Select “Service” as the document type, then click on “Choose”
- At the top, change the “Service receives selected” dropdown to “audio files”, and “any application” to “Finder”
- From the long list of actions on the left (optionally you can click in “Utilities” to narrow it down), select “Run Shell Script” and drag it into the gray area on the right.
- Change “Pass input” to “as arguments”
- In the prepopulated script body, change “echo” to “/usr/local/bin/lame -V 2”. Leave everything else as it is.
- Select “Save…” in the “File” menu and enter a service name, such as “Convert to mp3”
Here’s a screenshot of what this should look like:

Now open the Finder, locate a wave (or other audio) file, and right-click (or control-click) it. You should see a “Convert to mp3” option at the bottom of the context menu, and clicking on it should result on an MP3 file in the same folder.
In the example above, I used “-V 2” as the quality setting for lame. This generates a pretty high quality variable bitrate MP3 file. Of course you can adapt this to whatever quality settings you prefer. lame is extremely flexible and allows you to create many types of variable or constant bitrate MP3 files.
If you want to further experiment with Automator, you could even use the “Choose from List” action to prompt you for a quality setting after you choose “Convert to mp3”.
There you go! It’s still not quite as nice as a direct MP3 export, but at least it’s now a simple 2-step process.
