Python bindings for FluidSynth
This package contains Python bindings for FluidSynth. FluidSynth is a software synthesizer for generating music. It works like a MIDI synthesizer. You load patches, set parameters, then send NOTEON and NOTEOFF events to play notes. Instruments are defined in SoundFonts, generally files with the extension SF2. FluidSynth can either be used to play audio itself, or you can call a function that returns chunks of audio data and output the data to the soundcard yourself. FluidSynth works on all major platforms, so pyFluidSynth should also.
FluidSynth (2.0.0 or later)
(optional) NumPy 1.0 or later for some features
NOTE: If you don't need all the features of FluidSynth you may be interested in tinysoundfont-pybind which is a self-contained Python package that includes TinySoundFont for SoundFont playback and is permissively licensed.
To use the latest official release:
pip install pyfluidsynth
To use pre-release versions of this package, clone this repository, go to the repository directory, then do:
pip install --editable .
Here is a program that plays a chord for a second.
import time
import fluidsynth
fs = fluidsynth.Synth()
fs.start()
sfid = fs.sfload("example.sf2")
fs.program_select(0, sfid, 0, 0)
fs.noteon(0, 60, 30)
fs.noteon(0, 67, 30)
fs.noteon(0, 76, 30)
time.sleep(1.0)
fs.noteoff(0, 60)
fs.noteoff(0, 67)
fs.noteoff(0, 76)
time.sleep(1.0)
fs.delete()First a Synth object is created to control playback.
The start() method starts audio output in a separate thread.
To get sound, you need to choose an instrument. First load a
SoundFont with sfload(), then select a bank and preset with
program_select().
program_select(track, soundfontid, banknum, presetnum)To start a note, use the noteon() method.
noteon(track, midinum, velocity)To stop a note, use noteoff().
noteoff(track, midinum)You can also manage audio IO yourself and just use FluidSynth to
calculate the samples for the music. You might do this, for example,
in a game with WAV sound effects and algorithmically generated music.
To do this, create the Synth object but don't call start(). To
generate the next chunk of audio, call get_samples().
get_samples(len)The length you pass will be the number of audio samples. Unless
specified otherwise, FluidSynth assumes an output rate of 44100 Hz.
The return value will be a Numpy array of samples. By default
FluidSynth generates stereo sound, so the return array will be
length 2 * len.
To join arrays together, use numpy.append().
To convert an array of samples into a string of bytes suitable for sending
to the soundcard, use fluidsynth.raw_audio_string(samples).
Here is an example that generates a chord then plays the data using PyAudio.
import time
import numpy
import pyaudio
import fluidsynth
pa = pyaudio.PyAudio()
strm = pa.open(
format = pyaudio.paInt16,
channels = 2,
rate = 44100,
output = True)
s = []
fl = fluidsynth.Synth()
# Initial silence is 1 second
s = numpy.append(s, fl.get_samples(44100 * 1))
sfid = fl.sfload("example.sf2")
fl.program_select(0, sfid, 0, 0)
fl.noteon(0, 60, 30)
fl.noteon(0, 67, 30)
fl.noteon(0, 76, 30)
# Chord is held for 2 seconds
s = numpy.append(s, fl.get_samples(44100 * 2))
fl.noteoff(0, 60)
fl.noteoff(0, 67)
fl.noteoff(0, 76)
# Decay of chord is held for 1 second
s = numpy.append(s, fl.get_samples(44100 * 1))
fl.delete()
samps = fluidsynth.raw_audio_string(s)
print(len(samps))
print('Starting playback')
strm.write(samps)You can create a sequencer as follows:
import fluidsynth
seq = fluidsynth.Sequencer()This will by default create a sequencer that will advance at
a rate of 1000 ticks per second. To change the rate at which
the sequencer advances, you can give it the optional time_scale
parameter. As a clock source, it will use your system clock. In
order to manually advance the sequencer, you can give it the
parameter use_system_timer=False. You will then have to advance
it using sequencer.process.
In order to make the sequencer aware of your synthesizer, you have to register it:
fs = fluidsynth.Synth()
# init and start the synthesizer as described above…
synth_id = seq.register_fluidsynth(fs)You have to keep synth_id and use it as a target for the midi events
you want to schedule. Now, you can sequence actual notes:
seq.note_on(time=500, absolute=False, channel=0, key=60, velocity=80, dest=synth_id)If you use relative timing like above, the sequencer will
schedule the event the specified time from the current position.
Otherwise, if absolute is True (the default), you have to use
absolute track positions (in ticks). So the following code snippet
will do the same as the one above:
current_time = seq.get_tick()
seq.note_on(current_time + 500, 0, 60, 80, dest=synth_id)You can also register your own callback functions to be called at certain ticks:
def seq_callback(time, event, seq, data):
print('callback called!')
callback_id = sequencer.register_client("myCallback", seq_callback)
sequencer.timer(current_time + 2000, dest=callback_id)Note that event and seq are low-level objects, not actual Python objects.
You can find a complete example (inspired by this one from the fluidsynth library) in the test folder.
Not all functions in FluidSynth are bound.
Not much error checking, FluidSynth will segfault/crash if you call the functions incorrectly sometimes.
This project was originally created by Nathan Whitehead [email protected] but is the work of many. See CONTRIBUTORS.
Released under the LGPL v2.1 or any later version (this is the same as FluidSynth).
Copyright 2008--2024, Nathan Whitehead and contributors.