Graham Wakefield's Ambisonic externals¶

Summary¶

• Description: Ambisonic encoding, rotating and decoding up to 3rd order. For two or three dimensional speaker arrays.
• Developer: Graham Wakefield (based on CSL Signal Processing Library)
• Version: March 2006
• Platform: MaxMSP
• OS: MacOS, Windows
• License: ?
• Status of this entry: in progress

Parameter definition¶

Coordinate system convention¶

• Cartesian Coordinates: Mathematical System
• Spherical Coordinates: Blauert / Gerzon System

Parameter describing a sound source¶

• Ambisonics encoding is done in ambi.encode~ (for 1 source) or in ambi.encoden~ (for multiple sources)

parameter	description	data format	range	initial state	unit	example	misc
azimuth #	azimuth for the #th source	float			radians (default), can be changed with initial argument or angles message	azimuth 0 3.14	#-index starts with 0
elevation #	sets the elevation angle for the #th source	float			radians (default), can be changed with initial argument or angles message	elevation 0 0.1	#-index starts with 0
angles	sets units for azimuth and elevation	string	radians, degrees	radians	NA
	angle format	string	radians, degrees	radians	NA	ambi.encode~ degree	initial argument
	dimension	string	2D, 3D	2D	NA	ambi.encode~ 3D	initial argument
	number of sources	int	1..16		NA	ambi.encoden~ 16	initial argument for ambi.encoden~

Parameter describing a virtual space¶

• none

Parameter describing the position of loudspeakers¶

• Loudspeaker positions are set in ambi.decode~

parameter	description	data format	range	initial state	unit	example	misc
speaker_radians #	position of the #th speaker	int float float		equally spaced horizontal rig	radian	speaker_radians 0 -0.392699 0.	#-index starts with 0
speaker #	position of the #th	int float float		equally spaced horizontal rig	degree	speaker 0 -45 -45	#-index starts with 0
	number of speakers	int	1 .. 32	2	NA	ambi.decode~ 6	initial argument
gain	global gain	float			linear gain	gain 1.0
	dimension	string	2D, 3D	2D	NA	ambi.decode~ 3D	initial argument

Ambisonics specific parameter¶

parameter	description	data format	range	initial state	unit	example	misc
	encoding order	string	1st, 2nd, 3rd	1st	NA	ambi.encode~ 1st 2D degree
	decoding order	string	1st 2nd, 3rd	1st	NA	ambi.decode~ 3rd 2D
weights	decoder weights	list of max. 4 floats	0...1.0		linear	weights 0.7 1. 0.6 0.53
	decoder weights presets	string, or list of max 4 floats	none, default, in-phase, max-re	default	NA	ambi.decode~ 2D 3rd in-phase 8	can be also initial argument
width	mono/spatial balance	float	?	0.5	?	width 0.5	to be applied in ambi.decode~
tilt or pitch	transform around x-axis	float	0...360 / 0 .. 2π	can be set as initial argument	degree or radians (default)	tilt 90.	to be applied in ambi.rotate~
rotate or yaw	transform around z-axis	float	0...360 / 0 .. 2π	can be set as initial argument	degree or radians (default)	rotate 45.	to be applied in ambi.rotate~
tumble or roll	transform around y-axis	float	0...360 / 0 .. 2π	can be set as initial argument	degree or radians (default)	roll 3.14	to be applied in ambi.rotate~

Projects, sound, and music¶

• a large portion of the source code of these externals was used for the cosm project by Wesley Smith and Graham Wakefield

Media¶

References¶

• Wakefield, G. (2006). Third-Order Ambisonic Extension for Max/MSP with Musical Applications. In Proceedings of the 2006 International Computer Music Conference, pages 123 – 126, New Orleans, US.
• Pope, S.T. and Ramakrishna, C. (2003) The CREATE Signal Library ("Sizzle"): Design, Issues and Applications. In Proceedings of the 2003 International Computer Music Conference, Singapore.

External Links¶

• http://www.grahamwakefield.net/soft/ambi~/index.htm
• CREATE Signal Library