Spatial Sound in Virtual Reality

14 Working with Ambisonic Files

The recommended tool for working with multichannel (.wav) files is Reaper, a digital audio workstation that can edit and process multichannel audio. 1919https://www.reaper.fm/ In Reaper, drag and drop or import the .wav file (Insert -> Media File) and a four-channel track will be displayed in the timeline. You will need to setup the the routing for monitoring accordingly to your needs: binaural, 5.1, square, etc. You will also need a plugin to encode and decode the A-format file. There are several tools for doing this. The free plugin Soundfield by RØDE can be used when working with conventional media, but it does not support binaural rendering, thus, cannot be used to monitor with headphones. The Ambisonic Toolkit (ATK) works as a plugin for Reaper and offers several encoding / decoding options including binaural. 2020http://www.ambisonictoolkit.net/documentation/reaper/ The ATK works with Reaper and Supercollider, and there are MacOS and Windows versions. For Linux users, there is ambiX, a crossplatform Ambisonic processor in plugin format. It compiles to different orders, in our case, we only need 1st order. It also includes binaural rendering presets for different configurations of speakers. The presets use the Kemar HRTF measurements by Bill Gardner and Keith Martin at MIT Media Lab and decoder matrices from Fons Adriaensen. 2121https://sound.media.mit.edu/resources/KEMAR.html ,2222http://kokkinizita.linuxaudio.org/

Figure 11: A 1st Order (4 channels) Ambisonic file in Reaper