I have a bunch of midi files that I would like to convert to audio files through some kind of scripting on OS X. When searching for ways to do this, fluidsynth comes up time and Timidity are two terminal programs that comes up time and time again.

This is nice and all, but both these programs utilizes SoundFonts to generate the output, something that gets the job done but in all honesty doesn't make the final result sound especially good, especially when you compare it to what you can create by using something so relatively simple as Logic Pro X along with the default plug-ins (for example, the best sound font piano available still sounds dramatically worse than the default piano sound in Garageband).

Hence, my question is if there are some ways of batch creating audio files from midi files that utilizes the possibilities that my computer actually has to create high quality output?

  • A similar question on why the software synthesizers sound bad -- generally it's the sound font quality that matters. Commented Jun 24, 2015 at 16:49
  • I think you're on a hiding to nothing, tbh. Each of those files will have been optimised to the palette available to the programmer; even assuming they're using the General Midi spec, if it was made on a Yamaha & you listen on a Roland, the differences will be quite extreme. Hoping to be able to automate it through simple sound fonts is just not going to get you anywhere near what you'd want unless the instrumentation is extremely simple.
    – Tetsujin
    Commented Jun 25, 2015 at 8:41
  • @AbelCheung Exactly, and as I said, none of the SoundFonts that I've tried have been close to anything that I can create with for example Reason Pianos (which is understandable since the latter is using an advanced sampler while the first isn't).
    – Speldosa
    Commented Jun 25, 2015 at 21:13
  • @Tetsujin That certainly would hold true for multi-instrument MIDIs which you didn't create. I have, however, created all these MIDI files myself, and they're all just meant to be played with a single piano sound.
    – Speldosa
    Commented Jun 25, 2015 at 21:13

1 Answer 1


You need

  1. some loopback, either a virtual sound card, or just an analog cable;
  2. some command-line MIDI player (probably MIDImyAPP, or some AppleScript); and
  3. some command-line audio recorder.
  • Interesting suggestion. Thanks! I assume this solution would mean that you had to record everything in real time though, right? Wouldn't be feasible if you had a lot of files then.
    – Speldosa
    Commented Jun 25, 2015 at 21:16
  • I think this would be a lot easier in Windows if you have access to virtualbox to run windows inside of osx. I used to know a program but I forgot what it was called Commented Nov 9, 2017 at 21:12

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