Virtual Reality Era
In recent years, VR game engines, 3D installations and 360° videos on social media such as Facebook and YouTube have all become dependent on full-immersion, three-dimensional, 360-degree audio. The most popular audio standard for handling and delivering such audio is called Ambisonics. This format also allows sound files to be decoded to mono, stereo, quad, 5.1, 7.1 and much more.
What is Ambisonics?
Ambisonics sound effects libraries are captured with a special, full-sphere surround sound technique for 3D audio. Ambisonics is a method for recording, mixing and playing back three-dimensional 360º audio. It was invented in the 70s but was never commercially adopted until recently with the development of the VR industry which requires 360° audio solutions.
The most popular Ambisonics format nowadays, widely used in VR and 360 video, is a 4-channel format called Ambisonics B-format, which uses at least four channels to reproduce a complete sphere of sound.
There are two conventions within the Ambisonics B-format standard: AmbiX and FuMa. They are quite similar, but not interchangeable: they differ by the sequence in which the four channels are arranged, with AmbiX, for example, arranged WYZX instead of WXYZ.
What do those letters represent?
As we said before, the most basic Ambisonics format contains 4 channels, also known as first-order Ambisonics B-format. These four channels in first-order B-format are called W, X, Y and Z.
- W is an omni-directional polar pattern, containing all sounds in the sphere, coming from all directions at equal gain and phase.
- X is a figure-8 bi-directional polar pattern pointing forward.
- Y is a figure-8 bi-directional polar pattern pointing to the left.
- Z is a figure-8 bi-directional polar pattern pointing up.
An Ambisonics recording microphone is built of four microphone capsules encased closely together, arrangement known as tetrahedral array. Together these four capsules capture audio not only in the typical horizontal plane but also in the vertical one. These capsules are cardioid polar patterns, and the signals they record are usually referred to as Ambisonics A-format. The A-format is then transformed to B-format by a simple matrix to the WXYZ channels. This can be done by using specific plugins designed for this task. Sound Devices and Zoom recorders now include in-built Ambisonics decoding.
Decoding Ambisonics A-Format
In order to playback our Ambisonics recording, the A-format has to be transformed to B-Format. This is a list of Ambisonic software.
We recommend using the free Sennheiser Ambeo A-B Converter plugin as our recordings are done with a Sennheiser Ambeo. Once the recording is converted into B-format, you can use any of the software listed above that best fits your needs.
Why using Ambisonics?
Since the output of our Ambisonics recording B-format can be mono, stereo, quad, 5.0, 5.1, 7.0, 7.1 and so on, this turn Ambisonics recordings into a very flexible format, which can be used not only for VR, AR and 360º environments, but also for films, tv and games. It also allows you to adjust perspective of the recordings in real time with included “virtual microphone” software.