SSA Plugins creates tools for sound engineers and artists working with spatial sound. We specialize in Ambisonic plugins that make creating as easy as possible.
aXPlugins:
The aX Ambisonics Suite provides you with the tools for a complete signal chain that works with spatial and immersive audio, from encoding to decoding and many steps in between.
The aX Suite includes Ambisonics panning and monitoring plugins to help you immerse yourself in the world of spatial sound.
It also includes effects for use directly on Ambisonics signals: delay, EQ, compression, noise gate and de-esser.
What is Ambisonica?
Ambisonics is a spatial audio format that has been around since the 1970s. Since then, its popularity has risen and fallen several times, but with the advent of virtual reality (VR), it has been resurrected again. In fact, Ambisonics is now being used by some of the biggest video platforms on the web: YouTube and Facebook!
How does ambisonics work?
Ambisonics works in three stages: encoding, processing and decoding. The encoding step takes your mono or stereo track and converts (using a plugin like aXPanner) it into B-format, a multi-channel format in which the gain and polarity ratio between channels is determined by the position of the source (azimuth and elevation). B-format is independent of the playback stage and cannot be listened to directly. First order ambisonics (FOA) has 4 channels: W (omnidirectional), X, Y and Z (on Cartesian axes).
During the processing stage, you manipulate sound sources individually or as a group. This manipulation can include dynamic range compression, equalization, adding effects such as delay, etc. You can also rotate everything at the same time. Of course, format B signals must be handled with care so as not to damage the spatial information. The aX plugins were designed specifically with this in mind.
The decoding step converts from format B to speaker or headphone signals. Headphone decoding (currently the most convenient and common listening method) is done using Head-Related Transfer Functions (HRTF). They mimic the acoustic characteristics of the head and ears. This is called binaural decoding and is available in the aXMonitor series. The purpose of such a decoder is to create a scene that sounds realistic and not “inside the head” like normal stereo in headphones. Ideal for immersive virtual reality! Speaker decoding requires you to have quite a few speakers in the (ideally) area around your listening area, and it’s an amazing (but expensive) audio experience.
What is higher order ambisonics?
Higher Order Ambisonics (HOA) increases the number of B-format channels, thereby increasing the spatial resolution of the soundstage. The order of Ambisonics can theoretically go to infinity, but in practice DAW plugins are limited to the seventh order (64 channels).
HOA signals of a particular order contain all of the same channels needed for any lower order subset. For example, a 3rd order signal contains 1st and 2nd order channels as if you had encoded in that order directly. Just drop the channels at the end that correspond to the higher order components and you are downmixing to the lower order. Light!
What this means is it’s always best to mix in the highest order available (and your CPU can handle), even if it exceeds the current requirements for the project. Why? Because you will have the lower order signals you need, but you can also go back and get higher spatial resolution signals if/when decoding requirements improve. It’s the best way to prepare your Ambisonics work for the future!
Why use Ambisonics (higher order) for VR?
(Higher order) Ambisonics is a scene-based method, which means that processing can be effectively applied to the entire scene. For example, your final mix will probably have dozens of audio sources that you want to respond to the movements of the end user. Ambisonics allows you to rotate the sound field as a whole, instead of having to do it for every single source in your scene.
Ambisonics is currently used for spatial processing on YouTube 360 and Facebook360. It is also available in the next version 3.0 of VLC Media Player. They offer a huge opportunity to present your VR content to a wide audience. Since sound is key to immersing users in a VR scene, it’s worth learning how to use Ambisonics. To help you, I’ve put together a little tutorial here.
Compatible Hosts The
Ambisonics DAW is not compatible with all hosts or digital audio workstations (DAWs) because it requires a specific bus structure.
We have tested compatibility with various DAWs described here:
Reaper, Pro Tools Ultimate, Max 8.
Ambisonics is also supported on the following DAWS, although these have not been tested by us at this time. This is what we are working on. If you have confirmation that they work, we’d love to hear it.
Cubase 10, Nuendo, Pyramix.
