Synthesize audio from MIDI files.


Play a MIDI file

$ fluidsynth --audio-driver=[pipewire|pulseaudio] [path/to/soundfont.sf2] [path/to/file.midi]


fluidsynth [options] [ SoundFonts ] [ midifiles ]


FluidSynth is a real-time MIDI synthesizer based on the SoundFont(R) 2 specifications. It can be used to render MIDI input or MIDI files to audio. The MIDI events are read from a MIDI device. The sound is rendered in real-time to the sound output device.

The easiest way to start the synthesizer is to give it a SoundFont on the command line: 'fluidsynth soundfont.sf2'. fluidsynth will load the SoundFont and read MIDI events from the default MIDI device using the default MIDI driver. Once FluidSynth is running, it reads commands from the stdin. There are commands to send MIDI events manually, to load or unload SoundFonts, and so forth. All the available commands are discussed below.

FluidSynth can also be used to play a list of MIDI files. Simply run FluidSynth with the SoundFont and the list of MIDI files to play. In this case you might not want to open the MIDI device to read external events. Use the -n option to deactivate MIDI input. If you also want to deactivate the use of the shell, start FluidSynth with the -i option: 'fluidsynth -ni soundfont.sf2 midifile1.mid midifile2.mid'.

Run fluidsynth with the --help option to check for changes in the list of options.


fluidsynth accepts the following options:

-a, --audio-driver=[label]

The audio driver to use. "-a help" to list valid options

-c, --audio-bufcount=[count]

Number of audio buffers

-C, --chorus

Turn the chorus on or off [0|1|yes|no, default = on]

-d, --dump

Dump incoming and outgoing MIDI events to stdout

-E, --audio-file-endian

Audio file endian for fast rendering or aufile driver ("-E help" for list)

-f, --load-config

Load command configuration file (shell commands)

-F, --fast-render=[file]

Render MIDI file to raw audio data and store in [file]

-g, --gain

Set the master gain [0 < gain < 10, default = 0.2]

-G, --audio-groups

Defines the number of LADSPA audio nodes

-h, --help

Print out this help summary

-i, --no-shell

Don't read commands from the shell [default = yes]

-j, --connect-jack-outputs

Attempt to connect the jack outputs to the physical ports

-K, --midi-channels=[num]

The number of midi channels [default = 16]

-l, --disable-lash

Don't connect to LASH server

-L, --audio-channels=[num]

The number of stereo audio channels [default = 1]

-m, --midi-driver=[label]

The name of the midi driver to use. "-m help" to list valid options.

-n, --no-midi-in

Don't create a midi driver to read MIDI input events [default = yes]


Define a setting, -o name=value ("-o help" to dump current values)

-O, --audio-file-format

Audio file format for fast rendering or aufile driver ("-O help" for list)

-p, --portname=[label]

Set MIDI port name (alsa_seq, coremidi drivers)

-q, --quiet

Do not print welcome message or other informational output

-r, --sample-rate

Set the sample rate

-R, --reverb

Turn the reverb on or off [0|1|yes|no, default = on]

-s, --server

Start FluidSynth as a server process

-T, --audio-file-type

Audio file type for fast rendering or aufile driver ("T help" for list)

-v, --verbose

Print out verbose messages about midi events (synth.verbose=1) as well as other debug messages

-V, --version

Show version of program

-z, --audio-bufsize=[size]

Size of each audio buffer


The settings to be specified with -o are documented in the fluidsettings.xml hopefully shipped with this distribution or online at . We recommend viewing this file in a webbrowser, favourably Firefox.



Prints out list of help topics (type "help <topic>" to view details on available commands)


Quit the synthesizer

load filename

Load a SoundFont

unload number

Unload a SoundFont. The number is the index of the SoundFont on the stack.


Lists the current SoundFonts on the stack

inst number

Print out the available instruments for the SoundFont.

noteon channel key velocity

Send a note-on event

noteoff channel key

Send a note-off event

cc channel ctrl value

Send a control change event

prog chan num

Send program-change message

select chan sfont bank prog

Combination of bank-select and program-change


Print out the presets of all channels.

gain value

Set the master gain (0 < gain < 5)

interp num

Choose interpolation method for all channels

interpc chan num

Choose interpolation method for one channel

set [0|1]

Turn the reverb on or off

set num

Change reverb room size

set synth.reverb.damp num

Change reverb damping

set synth.reverb.width num

Change reverb width

set synth.reverb.level num

Change reverb level

set [0|1]

Turn the chorus on or off

set n

Use n delay lines (default 3)

set synth.chorus.level num

Set output level of each chorus line to num

set synth.chorus.speed num

Set mod speed of chorus to num (Hz)

set synth.chorus.depth num

Set chorus modulation depth to num (ms)


Reloads the default MIDI routing rules (input channels are mapped 1:1 to the synth)


Deletes all MIDI routing rules.

router_begin [note|cc|prog|pbend|cpress|kpress]

Starts a new routing rule for events of the given type

router_chan min max mul add

Limits the rule for events on min <= chan <= max. If the channel falls into the window, it is multiplied by 'mul', then 'add' is added.

router_par1 min max mul add

Limits parameter 1 (for example note number in a note events). Similar to router_chan.

router_par2 min max mul add

Limits parameter 2 (for example velocity in a note event). Similar to router_chan


Finishes the current rule and adds it to the router.

Router examples
router_begin note
router_chan 0 7 0 15
Will accept only note events from the lower 8 MIDI

channels. Regardless of the channel, the synthesizer plays the note on ch 15 (synthchannel=midichannel*0+15)

router_begin cc
router_chan 0 7 0 15
router_par1 1 1 0 64

Configures the modulation wheel to act as sustain pedal (transforms CC 1 to CC 64 on the lower 8 MIDI channels, routes to ch 15)


Peter Hanappe <>
Markus Nentwig <>
Antoine Schmitt <>
Josh Green <>
Stephane Letz <>
Tom Moebert <tom[d0t]mbrt[√ĄT]gmail[d0t]com>

Please check the AUTHORS and THANKS files for all credits


SoundFont(R) is a registered trademark of E-mu Systems, Inc.

Copied to clipboard