O1A Decoder - Octagon

Host Support

Host Type	Support
AAX	Yes, output mapped to 7.1
VST2	Yes

Audio

	Channels	Content
Input	4	O1A
Output	8	Speaker feeds for octagon (mapped to 7.1 for AAX)

Controls

Method

Description

This plugin takes a first order ambisonics (O1A) mix and decodes it as speaker feeds for eight speakers set out at the corners of an octagon.

Channels

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:

Channel	AAX/VST	Azimuth
1	Left at Front	+22.5
2	Right at Front	-22.5
3	Front at Right	-67.5
4	Back at Right	-112.5
5	Right at Back	-157.5
6	Left at Back	+157.5
7	Back at Left	+112.5
8	Front 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 O1A Decoding plugin library.

Controls

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.

Method	Description
Basic	This method produces a resilient decoding which should play well on a range of speaker systems including large venues.
Reconstruction	This 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 Reconstruction	This 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.

O1A Decoding