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Ambisonics is a surround sound technique covering the horizontal plane as well as regions above and below the listener. By way of its B-format sound field representation with spherical harmonics, it works independently of speaker setups. Notably, this makes it easy to rotate the sound with the listener. Anywhere a sound designer might need a more spherical sound representation, such as in providing ambient sounds or in developing VR, ambisonics is a viable option.
In addition to the Help material covering ambisonics in this and the following pages, you may find our Ambisonics in Wwise: Overview blog post of great interest. It delves deeper into the theory of ambisonics and how ambisonics can be used in Wwise for VR. Additionally, we offer a few small examples of ambisonics use within the Wwise Sample project, as described here .
Wwise makes it easy to import ambisonic files, submix other configurations to the ambisonics format, and ultimately have an ambisonic output playable on any of an increasing number of platforms which support ambisonics.
To use ambisonic files:
Import ambisonic B-format recorded files, which can be saved either as WAVs or AMBs, as you would any other audio file. Refer to Importing Media Files for more information.
Wwise imports ambisonic files (AMB or WAV) with the assumption they use the expected FuMa ordering with maxN normalization.
Specify an appropriate Audio Bus to be the Output Bus, as you would for any other sound object. Refer to Specifying the Output Routing for Objects for more information.
Wwise will mix channels as needed. Refer to Submixing Ambisonics for more information.
To have an ambisonics output:
Set an Audio Bus to have an ambisonics channel configuration of:
- First Order Ambisonics (first order, 4 channels)
- Second Order Ambisonics (second order, 9 channels)
- Third Order Ambisonics (third order, 16 channels)
Refer to the Available Ambisonics Bus Configurations table for more information on channel configurations.
Wwise will mix your source files that are output through the Audio Bus defined above into an ambisonic output.
If your Sound Engine Audio System specified in the Audio Preferences dialog is an Audio Device that supports ambisonics, then you can skip this initial step because the Master Audio Bus will already be set to ambisonics.
Specify a final output device that supports ambisonic channel configurations, such as a 3D binaural system.
If not an ambisonic-supported output, Wwise will automatically submix the corresponding channel output to the applicable standard output. Refer to Submixing Ambisonics for more information.
As described above, Wwise produces ambisonic and HOA (higher-order ambisonic) signals when one of the busses' Channel Configuration is set to Ambisonics #-#. These signals are decoded, meaning that they are transformed into a standard multichannel representation, such as stereo or 5.1, whenever a parent bus of an ambisonic bus has its channel configuration set to such a standard configuration.
The master Audio Bus inherits the configuration of the end point, which depends on the platform and is usually detected automatically. For now, most platforms will allow only a small selection of output configurations. These are typically stereo, 5.1, and 7.1. So, in general, the Master Audio Bus has a standard channel configuration, which forces decoding of child ambisonic busses to this configuration meaning Wwise will not output HOA directly.
However, it is possible to write a custom Audio Device plug-in that would declare an ambisonics configuration. In that case, a master Audio Bus could have an ambisonics channel configuration; therefore, Wwise would preserve, not decode, the HOA signal.
Alternatively, if you only need Wwise to dump the HOA in a file, you can simply insert a Wwise Recorder on an ambisonic bus. The generated file will be in AMB format (FuMa) with ambisonic order equal to that of the bus hosting the Recorder.