Ambisonic Audio with REAPER

Ambisonics is a way of representing a full-sphere sound field so you can capture, store, transmit, and later reconstruct it in different formats (headphones, speakers, VR environments, etc.).

Instead of recording sound channel-by-channel (like stereo’s L/R), Ambisonics encodes the sound field itself into a set of mathematical components — spherical harmonics — which describe how sound arrives from all directions.

Think of it as:

  • Encoding: Turning “sound coming from this angle” into a math-based format that’s independent of playback setup.
  • Decoding: Turning that math back into sound for a specific speaker arrangement or binaural headphone playback.

Ambisonic REAPER

This guide showcases how to create an Ambisonic REAPER composition that will spatialize sound inside the Immersive Arts Space.

  1. Download REAPER.
  2. Download Ambisonic for REAPER (its available fro Mac and Windows), and make sure it is imported in REAPER inside REAPER Preferences > VST by using the Re-Scan… > Re-scan VST path new/modifeid plug-ins.

Setup

  • In REAPER, add a new audio track called encoder, click the FX button and make sure to select VST3: AmbiEncoder_64 (ICST).
  • Add a second audio track called decoder, click FX and make sure to select VST3: AmbiDecoder (ICST).
  • Add additional audio tracks base on how many sound/tracks you wish to spatialize. Import and add your sound/composition in the sound_x track(s).
Audio tracks with encoder, decoder and two sounds.
  • Download the IAS speaker configuration (for 38 channels).
  • Import the IAS speaker configuration in REAPER. To do so in the decoder track, click the FX button, then click on the ⚙ > manage… > import once the file is imported make sure to select the new preset and apply.
IAS speaker settings import.
Decoder, displaying IAS speakers distribution.
Encoder, displaying the sound tracks positions.
  • Set the routing settings for the encoder, decoder and your sound tracks (on the keyboard press Ctrl+M to display the Route button). Follow the images below to configure each track.

Encoder routing settings

When we encode, we take the sound from a source (for example, in this case the sound_1 on track 3) and project it onto a set of spherical harmonic functions.

Decoder routing settings

When decoding, we take the Ambisonic channels (W, X, Y, Z, plus higher-order ones if present) and remix them for speaker arrays (e.g., cube, dome, 360° setup) or binaural output (headphones, stereo setup). The decoder applies speaker direction vectors or HRTF filters to reconstruct the directional cues.

Sound(s) routing settings

Last updated bystella speziali