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Easy to use MIDI to audio or playback via FluidSynth

Project description

PyPI version Supported Python versions License

Easily synthesize MIDI to audio or just play it.

It provides a Python and command-line interface to the FluidSynth synthesizer to make it easy to use and suitable for scripting and batch processing. In contrast, most MIDI processing software is GUI-based.


First, FluidSynth has a CLI which is not so straightforward to use. The goal was to make it easy to use as possible by making some parameters implicit.

fluidsynth -ni sound_font.sf2 input.mid -F output.wav -r 44100


midiplay input.mid
midi2audio input.mid output.wav

Second, we can have as easy interface scriptable in Python.

FluidSynth().midi_to_audio('input.mid', 'output.wav')

What it is not?

Note that is it not a Python binding to all the FluidSynth commands. If needed check out these packages instead:


You need at least one sound font. Normally you’d install them manually or via a package manager. midi2audio looks for its default sound font in ~/.fluidsynth/default_sound_font.sf2. It can be a symlink or an actual file.



You can install this package via pip.

pip install midi2audio

Or for development (changes in code take effect without reinstalling):

git clone
pip install -e midi2audio


I’d recommend adding the non-default libsndfile which supports output to FLAC and wide variety of audio formats. Otherwise only WAV, raw and a few other will be supported.

For Mac OS X we provide a script to automatically install FluidSynth with libsndfile and a basic sound font (Fluid R3 GM) and symlink it so that it’s recognized as a default sound font for this module. Note it it install installed via pip as another entry point.

Or install it manually:

brew install fluidsynth --with-libsndfile
mkdir -p ~/.fluidsynth
ln -s /path/to/my/sound_font.sf2 ~/.fluidsynth/default_sound_font.sf2

Check the script how to install a few additional (nice but bigger) sound fonts which are not installed by default.

Other OSs

Check you package manager and link your default sound font as descibed above.


Basically you can either play a MIDI file or synthesize it to audio. FluidSynth allows non-realtime synthesis which is faster than the playback.

Note that the audio format is determined from the audio file extension. The libsoundfile supports a lot of formats.


from midi2audio import FluidSynth

Play MIDI:


Synthesize MIDI to audio:

# using the default sound font in 44100 Hz sample rate
fs = FluidSynth()
fs.midi_to_audio('input.mid', 'output.wav')

# FLAC, a lossless codec, is supported as well (and recommended to be used)
fs.midi_to_audio('input.mid', 'output.flac')

Change the defaults:

# use a custom sound font

# use a custom sample rate

Command line interface

A shell sugars midi2audio and midiplay are provided instead of more verbose python -m midi2audio.

# play MIDI
$ midiplay input.mid

# synthesize MIDI to audio
$ midi2audio input.mid output.wav

# also to FLAC
$ midi2audio input.mid output.flac

# custom sound font
$ midi2audio -s sound_font.sf2 input.mid output.flac

# custom sample rate
$ midi2audio -r 22050 input.mid output.flac


Shoulders of giants

Thanks to the authors of FluidSynth for a nice command-line MIDI synthesizer!

Support the project

Need some consulting or coding work regarding audio processing, machine learning or big data? Drop me a message via email or LinkedIn. Or just say hello :).

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