O3A Decoder - Octagon

O3A Decoder - Octagon

Host Support

Host TypeSupport
AAXYes, output mapped to 7.1


Output8Speaker feeds for octagon (mapped to 7.1 for AAX)



This plugin takes a third order ambisonics (O3A) mix and decodes it as speaker feeds for eight speakers set out at the corners of an octagon.


The channel ordering for the speaker feeds assumes that the speakers are set out clockwise around the room, starting at the front and slightly to the left, so the first two channels are roughly where normal "Front Left" and "Front Right" speakers would be.

The channel ordering and speaker azimuths are:

1Left at Front+22.5
2Right at Front-22.5
3Front at Right-67.5
4Back at Right-112.5
5Right at Back-157.5
6Left at Back+157.5
7Back at Left+112.5
8Front at Left+67.5

In the table above, azimuth is measured anticlockwise (left) from the front. Note that these are mapped directly onto a 7.1 output in the AAX version of the plugin.

The plugin is available in the O3A Decoding plugin library.


Control: Method

Three methods are supported, "Basic", "Reconstruction" and "Tinted Reconstruction". Generally, "Basic" is recommended except where the speaker rig to be used for playback is known and has been set up accurately.

BasicThis method produces a resilient decoding which should play well on a range of speaker systems including large venues.
ReconstructionThis method controls the soundfield at the centre of the listening space to produce a clearer spatial image. It relies on the speaker layout being set up accurately.
Tinted ReconstructionThis variant of the Reconstruction method performs HRTF-based tinting on the audio stream to strengthen the spatial image. Again, it relies on the speaker layout being set up accurately.