Free Stuff

Free Stuff We Use

For the lawyers, we should point out that the things here do have licenses, and so aren't entirely free. We just mean the licenses are relatively unrestrictive, and you don't need to give away your hard-earned cash.

In our products, we use:


  • The Rapture3D Ambisonic Player uses libsndfile which is written by Erik de Castro Lopo and licensed under the LGPL. It's a really useful C library for reading and writing soundfiles. It's available from
  • Most of the Blue Ripple Sound graphical user interface components in our stand-alone applications have been written using wxWidgets. This is a cross-platform C++ GUI toolkit which is written by Julian Smart and others and is licensed under a variant of the LGPL. It is available from
  • The macOS version of Rapture3D uses the PortAudio Portable Real-Time Audio Library, which is Copyright 1999-2008 Ross Bencina, Phil Burk and others. See
  • Our studio plugins use libpng, by Guy Eric Schalnat, Andreas Dilger, John Bowler, Glenn Randers-Pehrson, and others. See
  • libBSR (part of Rapture3D for Unity) uses libogg and libvorbis, by Chris Montgomery and others. See
  • To extract data from AES69 or SOFA files, Rapture3D Advanced uses NetCDF (Copyright 1993-2014 University Corporation of Atmospheric Research/Unidata) and HDF5 (Copyright 1998-2006 The Board of Trustees of the University of Illinois and Copyright 2006-2014 The HDF Group). See and


We use the following HRTF data. Note that we process the data quite heavily, so don't blame the folk below if things don't work for you!

This website also uses GeoLite2 data created by MaxMind, available from


Free Stuff From Us

UHJ Stereo to Ambisonic B-Format Conversion

We provide a simple Windows UHJ stereo to Ambisonic B-Format conversion tool for Windows. It converts stereo material that is in the UHJ format (typically from Nimbus Records) into Ambisonic B-Format .AMB files (using FuMa encoding and just the WXY channels). It uses the "naive" speaker-agnostic approach to this.

O3A Core Plugins

The entire O3A Core plugin library can be downloaded free of charge.