![\"\"](\"https:\/\/sickgaming.net\/blog\/wp-content\/uploads\/2026\/03\/jsfx-on-fedora-linux-an-ultra-fast-audio-prototyping-engine.jpg\")
<\/p>\n<\/p>\n
Writing a real-time audio plugin on Linux often conjures up images of a complex environment: C++, toolchains, CMake, CLAP \/ VST3 \/ LV2 SDK, ABI\u2026<\/p>\n
However, there is a much simpler approach\u00a0: JSFX <\/p>\n
This article offers a practical introduction to JSFX and YSFX on Fedora Linux: we’ll write some small examples, add a graphical VU meter, and then see how to use it as an CLAP \/ VST3 plugin in a native Linux workflow.<\/p>\n
<\/span> <\/p>\n JSFX (JesuSonic Effects – created by REAPER [7<\/a>]) allows you to write audio plugins in just a few lines, without compilation, with instant reloading and live editing.<\/p>\n Long associated with REAPER, they are now natively usable on Linux, thanks to YSFX [3<\/a>], available on Fedora Linux in CLAP and VST3 formats via the Audinux repository ([4<\/a>], [5<\/a>]).<\/p>\n This means it’s possible to write a functional audio effect in ten lines, then immediately load it into Carla [8<\/a>], Ardour [9<\/a>], or any other compatible host, all within a PipeWire \/ JACK [11<\/a>] environment.<\/p>\n A citation from [1<\/a>] (check the [1]<\/a> link for images):<\/p>\n In 2004, before we started developing REAPER, we created software designed for creating and modifying FX live, primarily for use with guitar processing.<\/p>\n The plan was that it could run on a minimal Linux distribution on dedicated hardware, for stage use. We built a couple of prototypes.<\/p>\n These hand-built prototypes used mini-ITX mainboards with either Via or Intel P-M CPUs, cheap consumer USB audio devices, and Atmel AVR microcontrollers via RS-232 for the footboard controls.<\/p>\n The cost for the parts used was around $600 each.<\/p>\n In the end, however, we concluded that we preferred to be in the software business, not the hardware business, and our research into adding multi-track capabilities in JSFX led us to develop REAPER. Since then, REAPER has integrated much of JSFX’s functionality, and improved on it.<\/p>\n<\/blockquote>\n So, as you can see, this technology is not that new. But the Linux support via YSFX [3<\/a>] is rather new (Nov 2021, started by Jean-Pierre Cimalando).<\/p>\n A new programming language, but for what ? What would one would use JSFX for ?<\/p>\n This language is dedicated to audio and with it, you can write audio effects like an amplifier, a chorus, a delay, a compressor, or you can write synthesizers.<\/p>\n JSFX is good for rapid prototyping and, once everything is in place, you can then rewrite your project into a more efficient language like C, C++, or Rust.<\/p>\n Developing an audio plugin on Linux often involves a substantial technical environment. This complexity can be a hindrance when trying out an idea quickly.<\/p>\n JSFX (JesuSonic Effects) offers a different approach: writing audio effects in just a few lines of interpreted code, without compilation and with instant reloading.<\/p>\n Thanks to YSFX, available on Fedora Linux in CLAP and VST3 formats, these scripts can be used as true plugins within the Linux audio ecosystem.<\/p>\n This article will explore how to write a minimal amplifier in JSFX, add a graphical VU meter, and then load it into Carla as a CLAP \/ VST3 plugin.<\/p>\n The goal is simple: to demonstrate that it is possible to prototype real-time audio processing on Fedora Linux in just a few minutes.<\/p>\n No compilation environment is required: a text editor is all you need.<\/p>\n On Fedora Linux, YSFX comes in 3 flavours\u00a0:<\/p>\n YSFX is available in the Audinux [5<\/a>] repository. So, first, install the Audinux repository:<\/p>\n Then, you can install the version you want:<\/p>\n Here is a screenshot of YSFX as a VST3 plugin loaded in Carla Rack [8<\/a>]:<\/p>\n You can :<\/p>\n Here is a screenshot of the Edit window:<\/p>\n The \u00a0Variables<\/strong>\u00a0 column displays all the variables defined by the loaded file.<\/p>\n We will use the JSFX documentation available at [4<\/a>].<\/p>\n JSFX code is always divided into section.<\/p>\n In this example, we will use a slider value to amplify the audio input.<\/p>\n slider1, @init, @slider, @sample, spl0, spl1 are JSFX keywords [1<\/a>].<\/p>\n Description:<\/p>\n Here is a view of the result :<\/p>\n This example will create a slider that will produce a gain in dB.<\/p>\n Only the way we compute the gain changes.<\/p>\n Here is a view of the result :<\/p>\n This example adds protection against clipping and uses a JSFX function for that.<\/p>\n Here is a view of the result :<\/p>\n This example is the same as the one above, we just add a printed value of the gain.<\/p>\n The global structure of the code:<\/p>\n Here is a view of the result :<\/p>\n In this example, we will use a JSFX UI library to produce a better representation of the amplifier\u2019s elements.<\/p>\n First, clone the https:\/\/github.com\/geraintluff\/jsfx-ui-lib<\/a> repository and copy the file ui-lib.jsfx-inc<\/strong> into the directory where your JSFX files are saved.<\/p>\n The global structure of the example:<\/p>\n Here is a view of the result :<\/p>\n Now, produce some sound and use MIDI for that.<\/p>\n The core of this example will be the ADSR envelope generator ([10<\/a>]).<\/p>\n Global structure of the example:<\/p>\n Here is a view of the result :<\/p>\n Advantages of JSFX:<\/p>\n Limitations:<\/p>\n Advantages:<\/p>\n Limitations:<\/p>\n A functional audio effect can be written in just a few lines, adding a simple graphical interface, and then loaded this script as an CLAP \/ VST3 plugin on Fedora Linux. This requires no compilation, no complex SDK, no cumbersome toolchain.<\/p>\n JSFX scripts don’t replace native C++ development when it comes to producing optimized, widely distributable plugins. However, they offer an exceptional environment for experimentation, learning signal processing, and rapid prototyping.<\/p>\n Thanks to YSFX, JSFX scripts now integrate seamlessly into the Linux audio ecosystem, alongside Carla, Ardour, and a PipeWire-based audio system.<\/p>\n For developers and curious musicians alike, JSFX provides a simple and immediate entry point into creating real-time audio effects on Fedora Linux.<\/p>\n A free collection of JS (JesuSonic) plugins for Reaper.<\/p>\n Code available at: https:\/\/github.com\/chkhld\/jsfx<\/a><\/p>\n To install this set of YSFX plugins:<\/p>\n YSFX plugins will be available at \/usr\/share\/ysfx-chokehold.<\/p>\n Collection of JSFX effects.<\/p>\n Code available at: https:\/\/github.com\/geraintluff\/jsfx<\/a><\/p>\n To install this set of YSFX plugins:<\/p>\n YSFX plugins will be available at \/usr\/share\/ysfx-geraintluff.<\/p>\n Some JSFX effects from Cockos.<\/p>\n Code available at: https:\/\/www.cockos.com\/jsfx<\/a><\/p>\n To install this set of YSFX plugins:<\/p>\n YSFX plugins will be available at \/usr\/share\/ysfx-jesusonic.<\/p>\n A bundle of JSFX and scripts for reaper.<\/p>\n Code available at: https:\/\/github.com\/JoepVanlier\/JSFX<\/a><\/p>\n To install this set of YSFX plugins:<\/p>\n YSFX plugins will be available at \/usr\/share\/ysfx-joepvanlier.<\/p>\n LMS Plugin Suite – Open source JSFX audio plugins<\/p>\n Code available at: https:\/\/github.com\/LMSBAND\/LMS<\/a><\/p>\n To install this set of YSFX plugins:<\/p>\n YSFX plugins will be available at \/usr\/share\/ysfx-lms.<\/p>\n Community-maintained collection of JS effects for REAPER<\/p>\n Code available at: https:\/\/github.com\/ReaTeam\/JSFX<\/a><\/p>\n To install this set of YSFX plugins:<\/p>\n YSFX plugins will be available at \/usr\/share\/ysfx-reateam.<\/p>\n Reaper JSFX Plugins.<\/p>\n Code available at: https:\/\/github.com\/Justin-Johnson\/ReJJ<\/a><\/p>\n To install this set of YSFX plugins:<\/p>\n And all the YSFX plugins will be available at \/usr\/share\/ysfx-rejj.<\/p>\n Sonic Anomaly JSFX scripts for Reaper<\/p>\n Code available at: https:\/\/github.com\/Sonic-Anomaly\/Sonic-Anomaly-JSFX<\/a><\/p>\n To install this set of YSFX plugins:<\/p>\n YSFX plugins will be available at \/usr\/share\/ysfx-sonic-anomaly.<\/p>\n TiagoLR collection of JSFX effects<\/p>\n Code available at: https:\/\/github.com\/tiagolr\/tilr_jsfx<\/a><\/p>\n To install this set of YSFX plugins:<\/p>\n YSFX plugins will be available at \/usr\/share\/ysfx-tilr.<\/p>\n JSFX Plugins for Reaper<\/p>\n Code available at: https:\/\/github.com\/TukanStudios\/TUKAN_STUDIOS_PLUGINS<\/a><\/p>\n To install this set of YSFX plugins:<\/p>\n YSFX plugins will be available at \/usr\/share\/ysfx-tukan-studio.<\/p>\n [1] – https:\/\/www.cockos.com\/jsfx<\/a><\/p>\n [2] – https:\/\/github.com\/geraintluff\/jsfx<\/a><\/p>\n [3] – https:\/\/github.com\/JoepVanlier\/ysfx<\/a><\/p>\n [4] – https:\/\/www.reaper.fm\/sdk\/js\/js.php<\/a><\/p>\n [5] – https:\/\/aud<\/a>i<\/a>nux.github.io<\/a><\/p>\n [6] – https:\/\/copr.fedorainfracloud.org\/coprs\/ycollet\/audinux<\/a><\/p>\n [7] – https:\/\/www.reaper.fm\/index.php<\/a><\/p>\n [8] – https:\/\/github.co<\/a>m<\/a>\/falkTX\/Carla<\/a><\/p>\n [9] – https:\/\/ardour.org<\/a><\/p>\n [10] – https:\/\/en.wikipedia.org\/wiki\/Envelope_(music)<\/a><\/p>\n\n
JSFX for developers<\/h2>\n
YSFX plugin<\/h2>\n
\n
$ dnf copr enable ycollet\/audinux<\/kbd><\/pre>\n
$ dnf install ysfx\n$ dnf install vst3-ysfx\n$ dnf install clap-ysfx<\/pre>\n
![\"Screenshot](\"https:\/\/sickgaming.net\/blog\/wp-content\/uploads\/2026\/03\/jsfx-on-fedora-linux-an-ultra-fast-audio-prototyping-engine.png\")
<\/a><\/figure>\n\n
![\"Screenshot](\"https:\/\/sickgaming.net\/blog\/wp-content\/uploads\/2026\/03\/jsfx-on-fedora-linux-an-ultra-fast-audio-prototyping-engine-1.png\")
<\/a><\/figure>\nExamples<\/h2>\n
\n
A simple amplifier<\/h3>\n
desc:Simple Amplifier\nslider1:1<0,4,0.01>Gain @init\ngain = slider1; @slider\ngain = slider1; @sample\nspl0 *= gain;\nspl1 *= gain;<\/pre>\n
\n
![\"Screenshot](\"https:\/\/sickgaming.net\/blog\/wp-content\/uploads\/2026\/03\/jsfx-on-fedora-linux-an-ultra-fast-audio-prototyping-engine-2.png\")
<\/a><\/figure>\nAn amplifier with a gain in dB<\/h3>\n
desc:Simple Amplifier (dB)\nslider1:0<-60,24,0.1>Gain (dB) @init\ngain = 10^(slider1\/20); @slider\ngain = 10^(slider1\/20); @sample\nspl0 *= gain;\nspl1 *= gain;<\/pre>\n
![\"Screenshot](\"https:\/\/sickgaming.net\/blog\/wp-content\/uploads\/2026\/03\/jsfx-on-fedora-linux-an-ultra-fast-audio-prototyping-engine-3.png\")
<\/a><\/figure>\nAn amplifier with an anti-clipping protection<\/h3>\n
desc:Simple Amplifier with Soft Clip\nslider1:0<-60,24,0.1>Gain (dB) @init\ngain = 10^(slider1\/20); @slider\ngain = 10^(slider1\/20);\nfunction softclip(x) ( x \/ (1 + abs(x));\n); @sample\nspl0 = softclip(spl0 * gain);\nspl1 = softclip(spl1 * gain);<\/pre>\n
![\"Screenshot](\"https:\/\/sickgaming.net\/blog\/wp-content\/uploads\/2026\/03\/jsfx-on-fedora-linux-an-ultra-fast-audio-prototyping-engine-4.png\")
<\/a><\/figure>\nAn amplifier with a VU meter<\/h3>\n
desc:Simple Amplifier with VU Meter\nslider1:0<-60,24,0.1>Gain (dB) @init\nrms = 0;\ncoeff = 0.999; \/\/ RMS smoothing\ngain = 10^(slider1\/20); @slider\ngain = 10^(slider1\/20); @sample\n\/\/ Apply the gain\nspl0 *= gain;\nspl1 *= gain;\n\/\/ Compute RMS (mean value of the 2 channels)\nmono = 0.5*(spl0 + spl1);\nrms = sqrt((coeff * rms * rms) + ((1 - coeff) * mono * mono)); @gfx 300 200 \/\/ UI part\ngfx_r = 0.1; gfx_g = 0.1; gfx_b = 0.1;\ngfx_rect(0, 0, gfx_w, gfx_h); \/\/ Convert to dB\nrms_db = 20*log(rms)\/log(10);\nrms_db < -60 ? rms_db = -60; \/\/ Normalisation for the display\nmeter = (rms_db + 60) \/ 60;\nmeter > 1 ? meter = 1; \/\/ Green color\ngfx_r = 0;\ngfx_g = 1;\ngfx_b = 0; \/\/ Horizontal bar\ngfx_rect(10, gfx_h\/2 - 10, meter*(gfx_w-20), 20); \/\/ Text\ngfx_r = gfx_g = gfx_b = 1;\ngfx_x = 10;\ngfx_y = gfx_h\/2 + 20;\ngfx_printf(\"Level: %.1f dB\", rms_db);<\/pre>\n
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![\"Screenshot](\"https:\/\/sickgaming.net\/blog\/wp-content\/uploads\/2026\/03\/jsfx-on-fedora-linux-an-ultra-fast-audio-prototyping-engine-5.png\")
<\/a><\/figure>\nAn amplifier using the UI lib from jsfx-ui-lib<\/h3>\n
desc:Simple Amplifier with UI Lib VU\nimport ui-lib.jsfx-inc\nslider1:0<-60,24,0.1>Gain (dB) @init\nfreemem = ui_setup(0);\nrms = 0;\ncoeff = 0.999;\ngfx_rate = 30; \/\/ 30 FPS @slider\ngain = 10^(slider1\/20); @sample\nspl0 *= gain;\nspl1 *= gain;\nmono = 0.5*(spl0 + spl1);\nrms = sqrt(coeff*rms*rms + (1-coeff)*mono*mono); \/\/ ---- RMS computation ----\nlevel_db = 20*log(rms)\/log(10);\nlevel_db < -60 ? level_db = -60; @gfx 300 200\nui_start(\"main\"); \/\/ ---- Gain ----\ncontrol_start(\"main\",\"default\");\ncontrol_dial(slider1, 0, 1, 0);\ncut = (level_db + 100) \/ 200 * (ui_right() - ui_left()) + ui_left(); \/\/ ---- VU ----\nui_split_bottom(50);\nui_color(0, 0, 0);\nui_text(\"RMS Level: \");\ngfx_printf(\"%d\", level_db);\nui_split_bottom(10);\nuix_setgfxcolorrgba(0, 255, 0, 1);\ngfx_rect(ui_left(), ui_top(), ui_right() - ui_left(), ui_bottom() - ui_top());\nuix_setgfxcolorrgba(255, 0, 0, 1);\ngfx_rect(ui_left(), ui_top(), cut, ui_bottom() - ui_top());\nui_pop();<\/pre>\n
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![\"Screenshot](\"https:\/\/sickgaming.net\/blog\/wp-content\/uploads\/2026\/03\/jsfx-on-fedora-linux-an-ultra-fast-audio-prototyping-engine-6.png\")
<\/a><\/figure>\nA simple synthesizer<\/h3>\n
desc:Simple MIDI Synth (Mono Sine)\n\/\/ Parameters\nslider1:0.01<0.001,2,0.001>Attack (s)\nslider2:0.2<0.001,2,0.001>Decay (s)\nslider3:0.8<0,1,0.01>Sustain\nslider4:0.5<0.001,3,0.001>Release (s)\nslider5:0.5<0,1,0.01>Volume @init\nphase = 0;\nnote_on = 0;\nenv = 0;\nstate = 0; \/\/ 0=idle,1=attack,2=decay,3=sustain,4=release @slider\n\/\/ Compute the increment \/ decrement for each states\nattack_inc = 1\/(slider1*srate);\ndecay_dec = (1-slider3)\/(slider2*srate);\nrelease_dec = slider3\/(slider4*srate); @block\nwhile ( midirecv(offset, msg1, msg23) ? ( status = msg1 & 240; note = msg23 & 127; vel = (msg23\/256)|0; \/\/ Note On status == 144 && vel > 0 ? ( freq = 440 * 2^((note-69)\/12); phase_inc = 2*$pi*freq\/srate; note_on = 1; state = 1; ); \/\/ Note Off (status == 128) || (status == 144 && vel == 0) ? ( state = 4; ); );\n); @sample\n\/\/ ADSR Envelope [10<\/a>]\nstate == 1 ? ( \/\/ Attack env += attack_inc; env >= 1 ? ( env = 1; state = 2; );\n); state == 2 ? ( \/\/ Decay env -= decay_dec; env <= slider3 ? ( env = slider3; state = 3; );\n); state == 3 ? ( \/\/ Sustain env = slider3;\n); state == 4 ? ( \/\/ Release env -= release_dec; env <= 0 ? ( env = 0; state = 0; );\n); \/\/ Sine oscillator\nsample = sin(phase) * env * slider5;\nphase += phase_inc;\nphase > 2*$pi ? phase -= 2*$pi; \/\/ Stereo output\nspl0 = sample;\nspl1 = sample;<\/pre>\n
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![\"Screenshot](\"https:\/\/sickgaming.net\/blog\/wp-content\/uploads\/2026\/03\/jsfx-on-fedora-linux-an-ultra-fast-audio-prototyping-engine-7.png\")
<\/a><\/figure>\nComparison with CLAP \/ VST3<\/h2>\n
JSFX + YSFX<\/h3>\n
\n
\n
CLAP \/ VST3 in C\/C++<\/h3>\n
\n
\n
Conclusion<\/h2>\n
Available plugins<\/h2>\n
ysfx-chokehold<\/h3>\n
$ dnf install ysfx-chokehold<\/pre>\n
ysfx-geraintluff<\/h3>\n
$ dnf install ysfx-geraintluff<\/pre>\n
ysfx-jesusonic<\/h3>\n
$ dnf install ysfx-jesusonic<\/pre>\n
ysfx-joepvanlier<\/h3>\n
$ dnf install ysfx-joepvanlier<\/pre>\n
ysfx-lms<\/h3>\n
$ dnf install ysfx-lms<\/pre>\n
ysfx-reateam<\/h3>\n
$ dnf install ysfx-reateam<\/pre>\n
ysfx-rejj<\/h3>\n
$ dnf install ysfx-rejj<\/pre>\n
ysfx-sonic-anomaly<\/h3>\n
$ dnf install ysfx-sonic-anomaly<\/pre>\n
ysfx-tilr<\/h3>\n
$ dnf install ysfx-tilr<\/pre>\n
ysfx-tukan-studio<\/h3>\n
$ dnf install ysfx-tukan-studio<\/pre>\n
Webography<\/h2>\n