US 9,813,834 B2
Method for and apparatus for decoding an ambisonics audio soundfield representation for audio playback using 2D setups
Florian Keiler, Hannover (DE); and Johannes Boehm, Gottingen (DE)
Assigned to Dolby Laboratories Licensing Corporation, San Francisco, CA (US)
Appl. No. 15/30,066
Filed by Dolby Laboratories Licensing Corporation, San Francisco, CA (US)
PCT Filed Oct. 20, 2014, PCT No. PCT/EP2014/072411
§ 371(c)(1), (2) Date Apr. 17, 2016,
PCT Pub. No. WO2015/059081, PCT Pub. Date Apr. 30, 2015.
Claims priority of application No. 13290255 (EP), filed on Oct. 23, 2013.
Prior Publication US 2016/0309273 A1, Oct. 20, 2016
Int. Cl. H04S 3/02 (2006.01); G10L 19/008 (2013.01); H04S 5/02 (2006.01); H04S 3/00 (2006.01); H04S 7/00 (2006.01)
CPC H04S 3/02 (2013.01) [H04S 7/308 (2013.01); H04S 2400/11 (2013.01); H04S 2420/07 (2013.01); H04S 2420/11 (2013.01)] 10 Claims
OG exemplary drawing
 
1. A method for decoding an encoded audio signal in Ambisonics format for L loudspeakers at known positions, comprising:
adding at least one position of at least one virtual loudspeaker to the positions of the L loudspeakers;
generating a 3D decode matrix, wherein the positions of the L loudspeakers and the at least one virtual position are used and the 3D decode matrix has coefficients for said determined and virtual loudspeaker positions;
downmixing the 3D decode matrix, wherein the coefficients for the virtual loudspeaker positions are weighted and distributed to coefficients relating to the determined loudspeaker positions, and wherein a downscaled 3D decode matrix is obtained having coefficients for the determined loudspeaker positions; and
decoding the encoded audio signal using the downscaled 3D decode matrix, wherein a plurality of decoded loudspeaker signals is obtained,
wherein the coefficients for the virtual loudspeaker positions are weighted with a weighting factor g=1/√{square root over (L)},wherein L is number of loudspeakers.
 
5. An apparatus for decoding an encoded audio signal in Ambisonics format for L loudspeakers at known positions, comprising:
an adder unit adapted for adding at least one position of at least one virtual loudspeaker to the positions of the L loudspeakers;
a decode matrix generator unit adapted for generating a 3D decode matrix, wherein the positions of the L loudspeakers and the at least one virtual position are used and the 3D decode matrix has coefficients for said determined and virtual loudspeaker positions;
a matrix downmixing unit adapted for downmixing the 3D decode matrix, wherein the coefficients for the virtual loudspeaker positions are weighted and distributed to coefficients relating to the determined loudspeaker positions, and wherein a downscaled 3D decode matrix is obtained having coefficients for the determined loudspeaker positions; and
a decoding unit for decoding the encoded audio signal using the downscaled 3D decode matrix, wherein a plurality of decoded loudspeaker signals is obtained
wherein the coefficient for the virtual loudspeaker positions are weighed with a weighting factor g=1/√{square root over (L)},wherein L is the number of loudspeakers.