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ATK for Reaper : Read Me

This is the Ambisonic Toolkit (ATK) as a JSFX plugin suite for Reaper. It can be used with Reaper on OSX and Windows, and can also be used with other VST hosts on the Windows platform using the ReaJS plugin. ReaJS is part of the ReaPlugs plugin suite.

The Ambisonic Toolkit (ATK) is intended to bring together a number of tools and methods for working with Ambisonic surround sound. The intention is for the toolset to be both ergonomic and comprehensive, providing both classic and novel algorithms to creatively manipulate and synthesise complex Ambisonic soundfields.

The tools are framed for the user to think in terms of the soundfield kernel. By this, it is meant the ATK addresses the holistic problem of creatively controlling a complete soundfield, allowing and encouraging the composer to think beyond the placement of sounds in a sound-space and instead attend to the impression and image of a soundfield. This approach takes advantage of the model the Ambisonic technology presents, and is viewed to be the idiomatic mode for working with the Ambisonic technique.

We hope you enjoy the ATK!

For more information please visit the Ambisonic Toolkit website or send us an e-mail.








  1. Start Reaper.
  2. From the Options menu choose "Show REAPER resource path in explorer/finder".
  3. Unzip the ATK for Reaper archive.
  4. Follow the instructions suggested by the folder names in the unzipped archive. If the Data and Effects folders already contains ATK subfolder from a previous install, these can safely be deleted before copying.



When you run the installer, the required files are installed into the following folders in your home library folder:

~/Library/Application Support/ATK
~/Library/Application Support/Reaper/ColorThemes
~/Library/Application Support/Reaper/Effects/ATK
~/Library/Application Support/Reaper/presets


Additionally an alias (or rather a symlink) is created at:

~/Library/Application Support/Reaper/Data/ATK


that points to:

~/Library/Application Support/ATK


If you are using Ambisonic Toolkit with SuperCollider as well, the convolution kernels are installed in the same place and have the exact same content. We do not expect this to cause any conflicts.

If you want to take a look at the installed files and do not see the Library folder in Finder, please press the ALT button while clicking the "Go" menu in Finder. The Library folder will show up as an additional option.


Need Some Sound Files to Play Around With?

You can find a collection of sound files here:


Additional sound files can be grabbed from these fine sources:


And most of the catalogue of Nimbus Records are UHJ recordings:



Feedback and Bug Reports

Known issues are logged at GitHub.

If you experience problems or have questions pertaining to the ATK for Reaper plugins, please create an issue in the ATK-Reaper issue tracker.

If you use the plugins for some project, please let us know. We plan on adding a gallery of example artistic and creative projects that make use of the Ambisonic Toolkit.


List of Changes

Version 1.0.0.b11

Released 2021-11-04

Another maintenance release, ensuring compatibiility with Reaper v. 6.38

  • Pantophonic2D and Periphonic3D decoders now work with Reaper vv.6.38 - #75
  • Fixed typo in PsychoShelf filter, but the filter remains unstable - #78
  • Speed of sound corrected from 333 to 343 m/s in Proximity and Near Field transforms - #76

Under the hood updates:

  • macOS installer disk image built using more recent version of create-dmg (1.0.9)
  • Updated atk-matrices to v. 1.0.0
  • Updated cookdsp library to v. 0.5 - #74

Version 1.0.0.b10

Released 2016-09-12

Changes in this version

This is mostly a mainenance release fixing a number of issues introduced or discovered in beta 9.

  • Added pre-install script to OSX installer that erases earlier versions of the REAPER/Effects/ATK folder, preventing possible conflicts when a newer version is installed on top of an older one (issue #47).
  • Loading only the parts of CookDSP that are actually used, speeding up plugin load time on Windows (isse #46).
  • Fixed bug where stereo encoder would encode left channel to the right and vica versa (issue #56).
  • Fixing issue where rotation angle got mixed up in RotateTiltTumble transform plugin (issue #51).

Version 1.0.0.b9

Released 2016-07-24

IMPORTANT: This version breaks backwards compatibility regarding how azimuth angles are described in encoders, tranformsers and decoders.

It also breaks backwards compatibility with respect to channel configurations for the Quad Decoder.

Quad decoder

The Quad decoder now returns 4 channels only: L - R - Ls - Rs. Refer to the discussion in issue #26 for further details.

Azimuth angles

Azimuth angles are now defined to be positive in the counter-clockwise direction. The new azimuth convention aligns with standard ambisonic conventions, and description of azimuths is now consistent between the SuperCollider and Reaper implementations of ATK.

This is a change from prior beta-versions up to and including v.1.0.0.b7, and unfortunately it breaks backwards compatibility. As an example a planewave encoding done using previous beta verison now will be mirrored between left and right.

When we initially set out to make the Reaper port of ATK, we wanted this new design from the start. However, due to limitations in Reaper version 4 we had to implement azimuth as positive in clockwise rather than counter-clockwise direction. This was disussed in the paper ATK Reaper: The Ambisonic Toolkit as JSFX plugins by T. Lossius and J. Anderson, presented at the joint ICMC/SMC conference in Athens in 2014:

Due to current limitations in the Reaper JSFX API, there are some considerations to be made with respect to description of azimuths. The desired behaviour is that azimuths increase anti-clockwise. At the same time it is also preferable that for sources coming from the front half circle, moving the azimuth slider to the right results in the direction of the sound also moving clockwise to the right, similar to what happens when moving a regular stereo pan pot. The Harpex and Blue Ripple plugins both functions this way. In order to achieve this, horizontal azimuth sliders will need to be implemented with increasing values to the left. This is however currently not supported in Reaper JSFX, and for the time being ATK for Reaper uses azimuth values described according to a navigational coordinate system. If Reaper in the future is updated to support sliders with increasing values to the left, this design decision is likely to be reconsidered, and changed to use acoustic conventions.

REAPER v.5 added support for JSFX sliders with increasing values to the left, and hence this change is now being implemented. This implied changes to the following plugins:

  • Changed (breaks backwards compatibility)
    • Encoders
      • Planewave encoder now has positive azimuth in counter-clockwise direction (issue #34)
    • Transforms
      • Direct transform now has positive azimuth in counter-clockwise direction (issue #35)
      • Dominate transform now has positive azimuth in counter-clockwise direction (issue #36)
      • FocusPressPullZoom transform now has positive azimuth in counter-clockwise direction (issue #37)
      • Mirror transform now has positive azimuth in counter-clockwise direction (issue #38)
    • Decoders:
      • Mono decoder now has positive azimuth in counter-clockwise direction (issue #40)

If you need to maintain Reaper projects created using ATK for Reaper beta versions prior to 1.0.0.b8, you can insert a mirror transform

Other changes in this version

  • New features
    • New Reaper-theme, provided by Michael McCrea - When selecting the MultiChanMix theme in Reaper, two new Track Mixer Panel Layouts are available with larger multi-channel level meters (issue #23).
    • New encoder: AmbiXtoB - encodes a first order AmbiX format signal to FuMa B-format for further processing in Ambisonic Tooit. Supports 3DN and S3DN.
    • New decoder: BtoAmbiX - decodes a FuMa B-format (used for processing in Ambisonic Tooit) to first order AmbiX format. Supports 3DN and S3DN. S3DN is used to author ambisonic sound files for Google VR 360° videos.
    • Spreader encoder: Now support all sample rates equal to or higher than 44.1 kHz (issues #20, #30).
    • UHJ encoders: Now support all sample rates equal to or higher than 44.1 kHz (issues #20, #31).
    • Binaural decoder: CIPIC and Listen HRTFs now work woth all samle rates equal to or higher than 44.1 kHz (issues #18, #29, #32, #33).
  • Refactoring (these changes should not affect the behaviour of plugins):
    • Updated to install atk-kernels v. 1.2.1.
    • Installs atk-matrices, so far used for AmbiX conversions.
    • ATK for Reaper now uses v. 0.3 of the CookDSP library by Olivier Bélanger:
    • Introducing ATK library header file, simplifies maintenance of libraries and library dependencies (issue #39).
    • Have started to implement matrix library as object-oriented classes, adding new feature to read matrix file from disk. This is used for the AmbiX encoders and decoders.
  • On a side note:

Version 1.0.0.b7

Released 2016-05-23

  • Refactoring (these changes should not affect the behaviour of plugins):
    • The repository has been moved to Github. If you experience problems with the installers in this version, please let us know.
    • Removed redundant arguments from drawBackgroundImage() function - #16.
  • New features:
    • Stereo, Quadrophonic, 5_0 and Pantohponic 2D decoders: Added GUI for level metering and display of speaker positions/channel numbering
    • New decoder: Periphonic 3D - 3D dual ring, regular cylindrical decoder, with GUI for level metering and display of speaker positions/channel numbering

Version 1.0.0.b6

Released 2015-11-04

  • In Reaper 5 the name of the plugins are retrieved from the desc field rather than filename. The desc field of these plugins was previously used to provide documentation on the plugin. Now it has been changed to have more useful names of the plugins.

Version 1.0.b5

Released 2015-08-07

  • Added new utils plugin: MuteSoloChannels - can be used to mute or solo individula channels of a four-channel track. This can be useful when monitoring effect processing of signals within a Bformat => BtoA => SoundFXs => AtoB => B-format signal processing chain.
  • The 4channels plugins is now properly installed on Windows.
  • Set up the infrastructure required to provide Factory Presets for plugins. A number of presets are provided for the MuteSoloChannels effect.
  • Fixed bug in binaural decoder that would prevent the use of Spherical HRTFs at 88.2kHz and 96khz. Thanks to Juan Pampin for pointing this out!
  • Resolved: JS plugin automation data generated by GUI is not always properly recorded. This was a bug in Reaper, and was fixed in Reaper 4.75. Issue on the Reaper issue tracker:

Version 1.0.b4

Released 2014-10-04

  • New utility plugin "4channels": Can be used to extract 4-channel A- or B-format recording from sound file with additional channels, e.g. recorded in the field using a portable recorder such as Tascam DR680 or Sound Devices 788T.
  • Fixed an issue where matrix-based encoders could cause very loud signals if used on a track with insufficient number of channels.

Version 1.0.b3

Released 2014-09-09

  • Fixed issue where multi-channel matrix-based decoders could blow up when used on 2-channel (stereo) tracks.
  • Encode/UHJ: Corrected description of plugin in GUI
  • Decode/Binaural: Improving text describing in GUI of this plugin
  • Decode/5_0: Text description now provides information on output channels
  • Decode/Quad: Text description now provides information on output channels

Version 1.0.b2

Released 2014-09-3

  • Fixed issue where matrix-based transform plugins could blow up when used on 2-channel (stereo) tracks.
  • Fixed issue that prevented Omni encoder from producing sound.
  • OSX installer is now distributed as disk image.
  • Creation of Zip archive for Windows distribution is automoated using a Terminal script.
  • Info for beta testers has been merged into this readme document.
  • This Readme file is now versioned and maintained as markdown document, and converted to html by installer script using Pandoc. A minimum of CSS is used for it to look OK as a stand-alone HTML document as well as in the OSX installer.


Version 1.0.b1:

Released 2014-08-29

  • First beta release.





Copyright the ATK Community, Joseph Anderson, Joshua Parmenter and Trond Lossius, 2014.


The port of ATK as a set of Reaper JS plugins by Trond Lossius is supported by BEK, Bergen Centre for Electronic Arts.

The filter kernels distributed with the Ambisonic Toolkit are licensed under a Creative Commons Attribution-Share Alike 3.0 Unported (CC BY-SA 3.0) License and are copyright the Ambisonic Toolkit Community and Joseph Anderson, 2011.



Third Party Notices



ATK for Reaper makes use of the CookDSP library by Olivier Bélanger.

CookDSP is copyright (c) - 2014 - Olivier Belanger. Permission to use, copy, modify, and/or distribute this software for any purpose with or without fee is hereby granted, provided that the above copyright notice and this permission notice appear in all copies. CookDSP IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND FROM THE AUTHOR.


Diametric Decoder Theorem (DDT) decoding

Support for Gerzon's Diametric Decoder Theorem (DDT) decoding algorithm is derived from Aaron Heller's Octave code available at:

Benjamin, et al., "Localization in Horizontal-Only Ambisonic Systems" Preprint from AES-121, 10/2006, San Francisco

Implementation in the SuperCollider3 version of the ATK is by Joseph Anderson.


Irregular array decoding

Irregular array decoding coefficients (5.0) are kindly provided by Bruce Wiggins:

B. Wiggins, "An Investigation into the Real-time Manipulation and Control of Three-dimensional Sound Fields," PhD Thesis, University of Derby, Derby, 2004.


CIPIC HRTF Database (University of California)

V. R. Algazi, R. O. Duda, D. M. Thompson, and C. Avendano, "The CIPIC HRTF Database," in Proceedings of the 2001 IEEE ASSP Workshop on Applications of Signal Processing to Audio and Acoustics, New Paltz, NY, 2001.

"The CIPIC HRTF Database - CIPIC International Laboratory." [Online]. Available: [Accessed: 07-Jul-2011].

CIPIC Notices:

Copyright (c) 2001 The Regents of the University of California. All Rights Reserved



Further, the Regents of the University of California reserve the right to revise this software and/or documentation and to make changes from time to time in the content hereof without obligation of the Regents of the University of California to notify any person of such revision or change.

Use of Materials

The Regents of the University of California hereby grant users permission to reproduce and/or use materials available therein for any purpose- educational, research or commercial. However, each reproduction of any part of the materials must include the copyright notice, if it is present. In addition, as a courtesy, if these materials are used in published research, this use should be acknowledged in the publication. If these materials are used in the development of commercial products, the Regents of the University of California request that written acknowledgment of such use be sent to:

CIPIC- Center for Image Processing and Integrated Computing University of California 1 Shields Avenue Davis, CA 95616-8553


Listen HRTF Database (IRCAM)

"LISTEN HRTF DATABASE." [Online]. Available: [Accessed: 07-Jul-2011].

IRCAM Notices:

Copyright (c) 2002 IRCAM (Institut de Recherche et Coordination Acoustique/Musique). All Rights Reserved

Use of Materials

The Listen database is public and available for any use. We would however appreciate an acknowledgment of the database somewhere in the description of your work (e.g. paper) or in your development.


Olivier Warusfel, Room Acoustics Team, IRCAM 1, place Igor Stravinsky 75004 PARIS, France


MESA GLU Library

Code for calculating the inverse of a 4x4 matrix is based on the MESA implementation of the GLU library:

The default Mesa license is as follows:

Copyright (C) 1999-2007 Brian Paul All Rights Reserved.

Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the "Software"), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software.