FluidSynth(1)

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version 2.6.2 · 7 versions
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💅 FluidSynth — a SoundFont synthesizer 💅

okay so this is from the General Commands Manual, section 1, and it's literally the glow-up guide to FluidSynth. buckle up bestie 🎀

✨ NAME ✨

FluidSynth — a SoundFont synthesizer 🎹

🌸 SYNOPSIS 🌸

fluidsynth [options] [ SoundFonts ] [ midifiles ]

🦋 DESCRIPTION 🦋

FluidSynth is a real-time MIDI synthesizer based on the SoundFont(R) 2 specifications. It can 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. (fr fr, options change, always check 💀)

🌈 OPTIONS 🌈

fluidsynth accepts the following options:

  • -a, --audio-driver=[label] — the audio driver to use. -a help to list valid options 🎧
  • -b, --bank-offset=[num] — a positional flag that specifies the bank-offset for any Soundfonts following that flag. Can be specified multiple times. 🔁
  • -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, --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]
  • -o — 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

🧚 SETTINGS 🧚

The settings to be specified with -o are documented in the fluidsettings.xml hopefully shipped with this distribution or online at https://www.fluidsynth.org/wiki/settings/. We recommend viewing this file in a webbrowser, favourably Firefox. 🔥 (yes they really said "favourably", iconic)

👑 SHELL COMMANDS 👑

💜 GENERAL

  • help — prints out list of help topics (type help <topic> to view details on available commands)
  • quit — quit the synthesizer 👋

🎀 SOUNDFONTS

  • load filename [reset] [bankofs] — load a SoundFont onto the SoundFont stack. If reset is 1 (which is the implicit default), all currently in-use SoundFont presets will be re-evaluated with the newly loaded SoundFont taken into account. Optionally, you can specify a non-zero bank offset for the new SoundFont. For example the command load soundfont.sf2 0 10 will load the soundfont.sf2 with a bank offset of 10 without re-evaluating the presets.
  • unload number — unload a SoundFont. The number is the index of the SoundFont on the stack.
  • fonts — lists the current SoundFonts on the stack
  • inst number — print out the available instruments for the SoundFont.

🎹 MIDI MESSAGES

  • 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
  • channels — print out the presets of all channels.

🔊 AUDIO SYNTHESIS

  • 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

🌊 REVERB

  • set synth.reverb.active [0|1] — turn the reverb on or off
  • set synth.reverb.engine — select reverb engine. Engine selection applies at synth creation.
  • set synth.reverb.room-size 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

🌀 CHORUS

  • set synth.chorus.active [0|1] — turn the chorus on or off
  • set synth.chorus.nr 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)

🛰️ MIDI ROUTER

  • router_default — reloads the default MIDI routing rules (input channels are mapped 1:1 to the synth)
  • router_clear — 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
  • router_end — finishes the current rule and adds it to the router.

🌟 Router examples

router_clear

router_begin note

router_chan 0 7 0 15

router_end

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

router_add

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) 🎛️

🫶 AUTHORS 🫶

  • Peter Hanappe <hanappe@fluid-synth.org>
  • Markus Nentwig <nentwig@users.sourceforge.net>
  • Antoine Schmitt <as@gratin.org>
  • Josh Green <jgreen@users.sourceforge.net>
  • Stephane Letz <letz@grame.fr>
  • Tom Moebert <tom[d0t]mbrt[ÄT]gmail[d0t]com>

Please check the AUTHORS and THANKS files for all credits 💖

⚠️ DISCLAIMER ⚠️

SoundFont(R) was a registered trademark of Creative Technology Ltd.

no cap, that's the whole page bestie 🦋

and that's a wrap, mwah 💋 — this edition of the FluidSynth(1) manpage (General Commands Manual) is dated Feb 21, 2026. go make some slay little MIDI noises 🎶💅

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