Technical Notes

3D Mixing FAQ

Some Frequently Asked Questions about 3D mixing and the O3A plugins.

HOA

Higher Order Ambisonics is a mathematical framework for handling 3D sound scenes or "soundfields".

B-Format

B-Format is the main audio format used for Higher Order Ambisonics.

This is a multichannel audio format where the individual channels do not correspond directly to speaker feeds. There is no "front left" channel.

Binaural Audio and Head Tracking

Binaural stereo attempts to simulate 3D audio on headphones, by modifying sound as if it had travelled around your head and past your ears.

Custom Layouts

The "Advanced" edition of Rapture3D supports custom speaker layouts.

Decoding

In Higher Order Ambisonics, the main audio stream in use is B-Format. It must be "decoded" for playback.

HRTF: Amber

"Amber" is a 3D HOA "binaural" decoder method for headphones that is available in Rapture3D and our pro audio products.

O7A CPU Load

The O7A plugins use 64 channel ambisonic tracks and consequently create high CPU load. You will probably need a powerful modern computer to make good use of them.

Personalised HRTFs

Rapture3D Advanced v2.7.0 introduced support for the import of personalised HRTFs from AES69 files.

Personalised HRTFs are effectively acoustic models of an individual's head. Using these, it is possible to create synthetic binaural stereo which is tailored for a particular individual.

RAMBL

RAMBL provides a reference implementation of the N3D and SN3D equations in C using the ACN channel ordering sequence.

Rotations

B-Format audio stream can be rotated using matrix multiplication. This moves all material in the soundfield.

"Spatial Audio" means different things to different people. In the general sense, Ambisonics is a Spatial technology Audio. However, we often use the term to talk specifically about object-based formats like Dolby Atmos or Apple Spatial Audio.

3D7.1

3D7.1 is a speaker layout that is designed to work with the kit needed for a 7.1 system, but places the speakers differently.

Rapture3D Gaming - Stereo Hints & Tips

If you're using the Rapture3D game engine in Stereo, there are quite a few options. Hopefully this page will make them less confusing!