Method and apparatus for decoding stereo loudspeaker signals from a higher-order Ambisonics audio signal
Decoding of Ambisonics representations for a stereo loudspeaker setup is known for first-order Ambisonics audio signals. But such first-order Ambisonics approaches have either high negative side lobes or poor localisation in the frontal region. The invention deals with the processing for stereo decoders for higher-order Ambisonics HOA.
1. A method for decoding a Higher-Order Ambisonics (HOA) audio signal, the method comprising:
receiving the HOA audio signal;
determining a matrix G of panning function values, wherein the matrix G contains, for each of a number S of virtual sampling points on a sphere, gain vectors g 1 . . . g s , wherein at least a first panning function value for a first virtual sampling point located opposite to a loudspeaker position approaches zero, and at least a second panning function value for a second source located close to the loudspeaker position has a value not approaching zero; and
determining a decoding matrix based on the matrix G; and
rendering, by at least one processor, the HOA audio signal to stereo loudspeaker signals based on the decoding matrix.
2. The method of claim 1 , wherein the matrix G has a size L×S, wherein L corresponds to a number of loudspeakers.
3. The method of claim 2 , wherein the gain vectors g 1 . . . g s , are directed to achieve a panned mix in S directions of the L loudspeakers.
4. A non-transitory computer-readable medium having stored thereon instructions, that when executed by one or more processors, cause one or more processors to perform the method of claim 1 .
5. An apparatus for decoding a Higher-Order Ambisonics (HOA) audio signal, the apparatus comprising:
a first receiver configured to receive the HOA audio signal;
a first processor for determining a matrix G of panning function values, wherein the matrix G contains, for each of a number S of virtual sampling points on a sphere, gain vectors g 1 . . . g s , wherein at least a first panning function value for a first virtual sampling point located opposite to a loudspeaker position approaches zero, and at least a second panning function value for a second source located close to the loudspeaker position has a value not approaching zero;
a second processor for determining a decoding matrix based on the matrix G; and
a renderer for rendering the HOA audio signal to stereo loudspeaker signals based on the decoding matrix.