Ambisonics Mode

In Ambisonics mode OpenMixer can decode an incoming Ambisonics encoded audio stream.

Select the input source

1. Press any of the source buttons to select an input source, the button will light up and that source will be selected.

Activate Ambisonics mode

2. Press the Ambisonics button to enable the Ambisonics decoding mode.

Set input level

3. In Ambisonics mode only the first fader is active. Move the fader to set the input level for all channels in the selected source. If you move any other fader it will automatically reset to 0 after a couple of seconds.

Select the Ambisonics Decoder

4. OpenMixer has several decoders. Press the Ambisonics decoder button for the decoder you want to be active. Current choices include:

Full 3D decoder, 3rd order periphonic
2D decoder, 3rd order horizontal
3D decoder, 1st order periphonic
stereo UHJ decoder

Master level

5. This control is redundant but can be used to set the master level of the input source. Press the knob to reset the level to -10dB.

Select channel order and weights

6. Ambisonics streams can use different encodings and component weights, select the one that matches the encoder you are using. The default is FUMA order and weights (channel order is W X Y Z R S T U V K L M N O P Q for a full periphonic 3rd order signal), but you can also select ACN/SN3D (channel order is W Y Z X V T R S U Q O M K L N P for a full periphonic 3rd order signal). There is also an "ORIG" selection for FUMA ordering but non-standard component order (this is for backwards compatibility with old sessions, component order is W X Y U V P Q Z R S T K L M N O).

If you work on Ardour with the standard 3,3 Ambisonics panner you should select FUMA standard order and weights and connect the master 16 channel bus 1 to 1 to the first 16 system:hardware Jack ports.

Input Channel Ordering

The ordering of the channels for the inputs is as follows:

	ORIG	FUMA	ACN
channel 1	W	W	W
channel 2	X	X	Y
channel 3	Y	Y	Z
channel 4	U	Z	X
channel 5	V	R	V
channel 6	P	S	T
channel 7	Q	T	R
channel 8	Z	U	S
channel 9	R	V	U
channel 10	S	K	Q
channel 11	T	L	O
channel 12	K	M	M
channel 13	L	N	K
channel 14	M	O	L
channel 15	N	P	N
channel 16	O	Q	P

See this page for the meaning and equations that correspond to each component of an Ambisonics stream.

For the "ORIG" order the first 8 channels can contain a mixed order stream (3rd order horizontal and 1st order vertical), the next 8 channels add full periphonic 3rd order components.

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