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v3.x Blue Cat Plug’n Script

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Blue Cat Plug’n Script


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Blue Cat Plug'n Script

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Blue Cat Plug’n Script

Craft your own effects and instruments

Create your own audio and MIDI plug-ins right inside your DAW with Blue Cat Audio Plug’n Script.

Plug’n Script is an audio and MIDI scripting plug-in and application that can be programmed to build custom effects or virtual instruments, without quitting your favorite DAW software.

With this plug-in, you can write your own plug-in with very little knowledge about programming. If you do not care about programming, Blue Cat’s Plug’n Script can also be used as a regular multi-effects processor. Use it with existing scripts or use it to help someone else write a very particular utility you have been searching for for years and cannot find anywhere.

Write your own Scripts with Blue Cat Plug’n Script

If you are an experienced programmer, you will find in Plug’n Script a powerful development environment for audio plug-ins: prototype algorithms quickly, generate a state-of-the-art graphical user interface (GUI) without a single line of code, and export a VST, VST3, AAX, or Audio Unit plug-in, right from within your favorite DAW! Creating a plug-in has never been so fast!

This plug-in has been in our lab for several years and has been used to prototype lots of our existing plug-ins. It supports both scripts distributed as source code and pre-compiled binary scripts.

For source scripts, it uses the high-performance AngelScript scripting engine, originally developed for video games, with a JIT compiler that helps compile scripts into machine code for optimal performance. Starting with version 2, the plug-in also supports native (compiled) code and can load binary scripts built from C or C++ (or any language that can export C functions, such as Delphi, Fortran, .Net…), using the same interface as the angelscript version.

The syntax of the AngelScript language is close to Java, C#, C++, or JavaScript, making it very easy to learn. It is also convenient to reuse your scripts into native code or integrate code snippets found on the web into your script. Also, switching between angelscript and binary versions of the same script is very easy, requiring very few changes.

The plug-in includes dozens of audio and MIDI processing scripts as well as several virtual instruments and utilities to enhance your workflow. Use them as-is. Or, use them as examples to get started writing your own scripts. User scripts can be shared in the scripts repository, which also includes the factory scripts and native projects for reference.

To build complex effects chains using multiple scripts, you might be interested in Blue Cat’s PatchWork, which can host multiple instances of this plug-in in series or parallel. While writing scripts, you might also want to use our analysis tools to check their effect on the signal.


Plug’n Script Main Features:

  • Audio and MIDI scripting plug-in.
  • Build your own Audio and MIDI effects or virtual instruments.
  • Export your effect or instrument as an independent VST, VST3, Audio Unit or AAX plug-in.
  • Simple scripting syntax, using either the AngelScript language (similar to C++, Java or javascript) or C/C++ for native code.
  • Native binary scripts support (compiled C, C++ or Delphi, Fortran…).
  • Fully customizable user interface that adapts to scripts automatically. Build your own using Blue Cat’s KUIML language.
  • Up to 48 input parameters and 32 outputs, with full MIDI and automation control.
  • Use your favorite Integrated Development Environment (IDE) for editing.
  • Integrated JIT (Just In Time) compiler for optimal performance (scripts are not interpreted but compiled).
  • Includes 57 scripts with source code and 267 presets for sound synthesis, MIDI FX, audio FX (comp, gate, tremolo echo, filters, looper…), waveform generation, file playback/recording and more.
  • Side chain input and auxiliary outputs support.
  • Surround support (up to 8 audio channels).
  • Download free scripts from our audio & MIDI scripts repository.

Blue Cat Audio Standards:

  • Available as a standalone application and in most plug-in formats for Mac and Windows.
  • Full MIDI control and automation support, MIDI Learn.
  • No CPU load on idle: processing shuts down when fed with silence (optimal CPU usage).
  • Customizable user interface with transparency & zoom.
  • Automation and MIDI output: record output parameters as automation curves or send MIDI CC messages to other plug-ins for powerful side chain effects.
  • Smooth Bypass: noiseless plug-in activation / deactivation.
  • Undo/Redo.
  • Full-featured integrated presets manager.
  • Copy/paste the state of the plug-in between instances.
  • Any sample rate supported.


  • An SSE2-enabled processor (Pentium 4 or newer).
  • Microsoft Windows Vista, Windows 7, 8, or 10.
  • For the plug-in, any VST / AAX compatible host software (32 or 64-bit).
  • For the standalone application, an ASIO, MME, or WASAPI compatible audio interface (ASIO recommended).

Mac OS X

  • An Intel or Apple Silicon processor.
  • Mac OS 10.9 or newer.
  • For the plug-in, any VST / Audio Unit / AAX compatible application (64-bit).
  • For the standalone application, a Core Audio compatible audio interface.

V3.33 (2022/12/12)

  • actual parameter names (as set in the scripts) should now be visible in automation lanes in most host applications (may require a session reload in some cases).
  • VST: improved parameter value display in some host applications.
  • The application is now using Apple’s hardened runtime, and the installer has been notarized to avoid security warnings on Mac. You may have to add the –force option to code signing command line if you are signing your binaries.
  • Added Apple Silicon support for AAX plug-in format.
  • Added Ambisonic and alternate surround formats support for Pro Tools (Plug’n Script only: not yet for exported plug-ins).

V3.32 (2022/06/23)

  • Single Installer on Mac (all plug-ins formats).
  • Full Apple Silicon (M1 processor) support.
  • New “network slave” mode to run as an audio/MIDI processing server for the Connector plug-in.
  • Windows: ASIO Control panel can now be launched from the audio settings window in the application.
  • Audio engine can now be restarted from the audio settings window in the application.
  • Dropped 32-bit support on Mac.
  • Now requires MacOS 10.9 and newer.
  • Improved MIDI events timing precision in the application.
  • Added MIDI tap tempo support for standalone application.
  • Standalone application can now send MIDI events to external devices.
  • Select individual MIDI I/O in standalone application.
  • In most plug-in formats, internal audio I/O configuration can now be selected regardless of the configuration defined by the host.
  • Improved MIDI & automation control settings with lock, reset and “save as global setting” capabilities.
  • The plug-in and app can now send MIDI events back to a control surface when MIDI-enabled parameters are modified in the user interface.
  • It is now possible to export plug-ins with an unlimited number of parameters.
  • The user interface does not throw errors anymore when using more than 48 input parameters in a script (they are simply not displayed).
  • Fixed latency compensation changes not always picked up by host applications.
  • VST3: fixed random crash in Ableton Live 11 upon load.
  • VST3: fixed parameters update issues in Studio One when bouncing tracks.
  • Windows: fixed an issue with unicode window titles.
  • MacOS: fixed export window colors in dark mode.
  • MacOS: fixed plug-in editor positioning issues in some hosts with some particular zoom values

V3.31 (2021/02/16)

  • Arrow keys can now be used to navigate presets, in the main view or in the presets browser.
  • Next/Previous preset can now be triggered by MIDI CC commands.
  • New DSP workload meter in the status bar.
  • Smoother presets switching.
  • Improved smooth plug-in bypass.
  • Level meters do not use CPU anymore when the user interface is closed.
  • Many optimizations for faster GUI loading and reduced memory usage.
  • Improved performance for native DSP scripts.
  • Improved plug-in loading performance, especially when having many user presets.
  • Full Unicode support added to Windows platform.
  • New Experimental Xml parser/writer for Angelscript.
  • new KUIML actions to display presets or global settings windows: OpenPresetsSettings, OpenGlobalSettings.
  • KUIML errors can now be redirected to a log file (log_file_path directive in SKIN)
  • KUIML errors display in popup window can be disabled (show_messages=”false” in SKIN)
  • window.loaded attribute is now properly set to false and sends events when the plug-in window is closed.
  • updated Angelscript filesystem object (fixes several issues with file dates).
  • VST3: fixed a GUI update issue when using automation and long buffers in Cubase (parameters values jumping).
  • Fixed an issue with random Audio Unit validation failures with exported plug-ins on MacOS older than 10.12.
  • Fixed transport info sometimes not properly initialized for exported plug-ins using native DSP.
  • Fixed an issue with endValues not properly set when using processBlock in exported plug-ins (Native scripts only).
  • Fixed crash when defining actions after using the content attribute in INCLUDE directive.
  • Mac: fixed intToString Angelscript function crash.
  • Mac: fixed GUI performance issues on native P3 displays and improved performance on other displays.
  • Mac: fixed mouse wheel that required large movements to change parameter values.
  • Mac: fixed mouse cursor flickering issues.
  • Mac: fixed Esc key not closing fine edit parameter dialog.

V3.3 (2020/06/15)

  • Custom graphics and resource files are now be copied when exporting scripts as independent VST, VST3, AU or AAX plug-ins (SCRIPT_DATA_PATH folder).
  • New version of the KUIML GUI programming language (2.7), with new widgets, new mouse and keyboard events handling features, system script function to execute shell commands and more.
  • New version of the Angelscript Engine (2.34).
  • New high-resolution graphics for knobs.
  • New background mode (“None”) to create entirely custom user interfaces.
  • New icon for the Plug’n Script Application.
  • Reduced disk footprint.
  • Fixed crash in exported VST3 plug-in when using input strings in scripts.
  • Fixed crashes when using build-time script in KUIML widgets.
  • Fixed gui.capture objects that could be exposed twice in KUIML objects.
  • Fixed png or svg images alpha mask not properly loaded (was ignored)
  • Fixed ignore_missing attribute for LOAD_FONT that still triggered an error.
  • Mac application now fully supports dark mode on Mac OS Mojave and newer.
  • Mac: fixed settings panel rendering issues in dark mode on Mac OS Mojave and newer.
  • Mac: Fixed keyboard not responding in registration panel in some host applications (LUNA, Garage Band…).
  • Mac: Fixed demo version that could hang Logic when reloading projects using the plug-in.
  • Mac: fixed Retina scaling issue on buffered widgets in apps built with Mac OS 10.14 SDK and newer.

Blue Cat’s Plug’n Script 3.2

This new version lets you export AAX plug-ins for Pro Tools and Media Composer, encrypt the DSP scripts to protect your code and share any type of data with the user interface.

It also includes a new presets browser, full MIDI support for VST3, KUIML 2.6 GUI programming language, and many other improvements.

How To Create AAX PlugIns For Pro Tools And Media Composer

With Blue Cat Plug'n Script 3.2 you can export audio and MIDI plug-in creations as AAX plugins, which can be used in Avid Media Composer and Pro Tools.


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