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Meta XR Audio SDK for Unreal - Ambisonics

Updated: Apr 15, 2026

Overview

The plugin supports ambisonics in the AmbiX (ACN/SN3D) format. You must use this feature with 4-channel ambisonic tracks.

By the end of this document, you’ll be able to:

Create a Soundfield Submix that uses the Meta XR Audio Decoder.

Route an ambisonic audio cue to be decoded by Meta XR Audio.

Identify how the plugin encodes non-ambisonic sources routed through a Soundfield Submix.

Understand how headset and source orientation affect ambisonic playback.

The Meta XR Audio SDK renders ambisonics with an advanced spherical harmonic binaural renderer. Compared to traditional rendering methods that use virtual speakers, this renderer provides a better frequency response, better externalization, less spatial smearing, and also uses less compute resources.

Prerequisites

Before you can use the Meta Ambisonic Decoder for Unreal, make sure to set up the plugin. See the steps in Set Up the Meta Spatializer Plugin for Unreal.

Implementation

Ambisonic sounds in Unreal must be routed to a Soundfield Submix instead of a standard Submix. To apply ambisonics to an event, follow the steps below:

Drag and drop your ambisonic file into the Content Browser. Double click the file to go to its settings. Ensure that ambisonics are enabled for this file as shown below:

Unreal setting to confirm a file is intended to be played back as ambisonics.

Right click in the content browser and click Audio > Mix > Soundfield Submix.

Right click in the content browser and click Audio > Sound Cue.

Double click the Sound Cue and add the ambisonic file to the playback for this sound cue. Under Submix > Base Submix, select the Soundfield Submix created in step 2.

Setting a sound cue to propagate through a soundfield submix.

Double click the Soundfield Submix created in step 2. Set the Soundfield > Soundfield Encoding Format to MetaXR Binaural.

Ambisonic encoding

Unreal has a unique feature which allows you to route audio tracks that are not ambisonic into a Soundfield Submix with the Meta XR Audio ambisonic format enabled. An example input would be a mono source or a stereo source. When this occurs while Meta XR Audio is set as the Soundfield Encoding Format, the plugin renders each channel of the input as a separate binaural source. For example, a stereo input would have the left channel binaurally rendered as a source 90 degrees to the left and the right channel binaurally rendered 90 degrees to the right.

Warning: If you set the default Spatialization Plugin in your project settings to Meta XR Audio, routing non-ambisonic sources through the ambisonic encoder produces silence. The plugin logs the following error: “Meta Ambisonic Encoding cannot be used while Meta XR Audio is set as the active spatialization plugin. It will output silence.”

Using both methods is not supported. Set up your non-ambisonic sources as regular Sound Cues and route them into regular Sound Submixes while the Spatialization Plugin is set to Meta XR Audio. This approach offers better controls and future compatibility. You can still perform standard ambisonic processing (ambisonic input with binaural output) while using regular spatialization.

Learn more

Rotating either the headset (the AudioListener) or the audio source itself affects the ambisonic orientation. Use this to create sound fields that respond to head movement or to reposition ambisonic content relative to the listener.

You can control the level of ambisonic audio sources in your scene by customizing the Volume Rolloff curve for each audio source.

The plugin currently supports first-order ambisonics (4 channels) only. Higher-order ambisonic files produce silence.