Source positioning in ambisonics derives from game object and listener positions at the moment of mixing, as is the case with any other channel configuration. Consequently, ambisonic-set sound objects can be submixed with other configurations; however, you may lose spatial information if you do so. For example, if your submix is 7.1 then you will have lost all height information when it is mixed into the ambisonics Audio Bus. Likewise, with a 7.1.4 submix, objects originally located below the listener's ears will appear to be at ear level. Therefore, it is recommended to use ambisonics for submixes as well. You may use lower orders if spatial precision is less important.
Wwise will automatically convert audio to and from ambisonics according to routing of different configurations. The resulting output depends on the different channel configurations used and whether the positioning type is 2D or 3D. The following table provides general information on the routing behavior according to these factors.
|
Routing |
2D Positioning Behavior |
3D Positioning Behavior |
|---|---|---|
|
Standard configuration to ambisonics |
The signal is encoded to ambisonics. Mono sources are encoded directly to the W (omni) channel. For multichannel sources, each channel is considered like a mono source with an incident angle based on the channel. For example, a stereo source will have its left channel encoded as a mono source located at 45 degrees to the left, and its right channel encoded as a mono source located at 45 degrees to the right. Here is an exhaustive list of input channel angles in degrees (positive clockwise):
Encoding a source with a given angle of incidence is straightforward. |
The signal is encoded to ambisonics with an incident angle based on the game object position relative to the listener position and orientation. Multichannel files, spread, and focus are handled exactly as they are with standard configurations: virtual sources representing various input channels are laid out around the listener based on the game object, listener, focus, and spread, and then are encoded accordingly. Refer to Defining the Attenuation curves for Various Object Properties for more details about spread and focus. |
|
Ambisonics to ambisonics |
Direct speaker assignment occurs. If the input has a higher order, the extra channels are dropped. If the input has a lower order, the extra channels of the output are left silent. |
The ambisonic bed is rotated with respect to the relative orientations of the game object and listener. When input and output orders differ, rotation is computed on the smaller order and higher orders are silenced. |
|
Ambisonics to standard configuration |
The ambisonics signal is decoded to the output configuration using speaker positions specified by the game. Refer to
|
The ambisonic bed is rotated with respect to the relative orientations of the game object and listener, and then decoded to the output standard configuration as is the case for 2D positioning. |
![[Caution]](/images/2018.1.11_6987/?source=Help&id=caution.png) |
Caution |
|---|---|
|
Encoding 2D mono sources to the W (omni) channel, instead of treating them as sources oriented directly in front, creates an abnormal playback. A 2D mono source routed to an ambisonic bus that is routed to a bus with standard configuration will result in the mono source playing back in all the output channels. This differs from typical behavior in Wwise where 2D mono sources are sent only to the C or L and R channels. |
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