I often need to convert a bunch of MIDI files to MP3 for teaching and lecturing.
I used to use the venerable Timidity++ on Linux, but since switching to the Mac I could never quite get it to work. There are a few commercial graphical apps for the Mac and you can even use Garageband, but I always wanted to be able to convert MIDI files using the command line since it’s easier and I can automate the whole process. On the Mac we can use Timidity++ or Fluidsynth, both available using homebrew.
brew install libsndfile lame brew install --with-libsndfile fluidsynth
If everything is working properly, when you run fluidsynth -T help you should see something like the following:
kroger@orestes $ fluidsynth -T help FluidSynth version 1.1.6 Copyright (C) 2000-2012 Peter Hanappe and others. Distributed under the LGPL license. SoundFont(R) is a registered trademark of E-mu Systems, Inc. -T options (audio file type): 'aiff','au','auto','avr','caf','htk','iff','mat','mpc','paf','pvf','raw','rf64','sd2','sds','sf','voc','w64','wav','wve','xi' auto: Determine type from file name extension, defaults to "wav"
With fluidsynth working, the conversion is simple. Just pass a SoundFont and a MIDI file as parameters and you should be good to go:
fluidsynth -F output.wav ~/Soundfonts/my-soundfont.sf2 myfile.midi lame output.wav
If you are lazy, check this bash script. It accepts multiple MIDI files and removes the intermediate WAV file.
Timidity++ is my go to program when using Linux and I’m super happy it’s available on homebrew.
brew install timidity
You may need to create a configuration file at /usr/local/Cellar/timidity/2.14.0/share/timidity/timidity.cfg and list where your SoundFonts are. For instance, in my timidity.cfg file I have:
You can read more about the configuration format by using its man page:
There you go. We have two ways to convert MIDI files to MP3 on the Mac using free software.