3D7.1
From Ambisonia
3D7.1 is a variant of the 7.1 surround speaker layout. It is common for computers to include hardware which supports 7.1 surround sound. The ordinary 7.1 surround speaker layout places three speakers at the front of the room, two at the sides and two at the back. Further, a subwoofer (the ".1" in the name) is placed somewhere in the room. This arrangement of the main seven speakers puts all speakers at the same height, which does not enable the full-sphere possibilities of Ambisonics.
The 3D7.1 speaker layout (invented by Simon N Goodwin at Codemasters) is designed to use existing 7.1 sound hardware. All you have to do is change where you put your speakers. It is also designed so that stereo and 5.1 material will still play back well. The advantage is that games or other 3D audio software that can handle the new speaker arrangement can produce sound in full 3D.
Some Codemasters research on the subject is available.
[edit] Speaker Locations
To change from a 7.1 to a 3D7.1 speaker layout, speakers should be moved as follows:
| 7.1 Speaker | New 3D7.1 Speaker Location | X | Y | Z |
|---|---|---|---|---|
| Front Left | Upper Front Left | +0.577 | +0.707 | +0.408 |
| Front Right | Upper Front Right | +0.577 | −0.707 | +0.408 |
| Front Centre | Front Centre (ear-level) | +1.000 | 0.000 | 0.000 |
| Subwoofer | Subwoofer | |||
| Back Left | Upper Back Centre | −0.577 | 0.000 | +0.816 |
| Back Right | Lower Front Centre | +0.577 | 0.000 | −0.816 |
| Side Left | Lower Back Left | −0.577 | +0.707 | −0.408 |
| Side Right | Lower Back Right | −0.577 | −0.707 | −0.408 |
[edit] Decoding
The recommended Ambisonic decoding for this layout uses only six of the eight speakers, leaving the ear-level Front Centre (which may be a dedicated dialogue speaker) and Subwoofer out of the main decode. The remaining six speakers sit at the corners of a regular octahedron. If bass management is needed it is assumed that a subwoofer feed will be provided by the AV receiver.
3D7.1 is a preset layout in all versions of Rapture3D.
3D7.1 is also supported on the PlayStation 3 version of the Codemasters game Colin McRae: DiRT2, released in August 2009.
