Obtaining sparseness information for higher order ambisonic audio renderers

1. A device configured to render higher order ambisonic coefficients, the device comprising:

one or more processors configured to:

obtain, from a bitstream that includes an encoded version of the higher order ambisonic coefficients, sparseness information indicative of a sparseness of a matrix used to render the higher order ambisonic coefficients to a plurality of speaker feeds, and value symmetry information that indicates value symmetry of the matrix;

obtain, from the bitstream, a reduced number of bits used to represent the matrix;

based on the sparseness information, the value symmetry information, and the reduced number of bits, reconstruct the matrix;

render, using the reconstructed matrix, the higher order ambisonic coefficients to the plurality of speaker feeds; and

output the plurality of speaker feeds to drive one or more loudspeakers; and

a memory coupled to the one or more processors, and configured to store the sparseness information.

2. The device of claim 1 , wherein the one or more processors are further configured to determine a speaker layout for which the matrix is to be used to render the plurality of speaker feeds from the higher order ambisonic coefficients.

3. The device of claim 1 , further comprising a speaker configured to reproduce a soundfield represented by the higher order ambisonic coefficients based on the plurality of speaker feeds.

4. The device of claim 1 , wherein the one or more processors are further configured to obtain audio rendering information indicative of a signal value identifying an audio renderer used when generating the multi-channel audio content, and render the plurality of speaker feeds based on the audio rendering information.

5. The device of claim 4 ,

wherein the signal value includes the matrix used to render the higher order ambisonic coefficients to the multi-channel audio data, and

wherein the one or more processors are configured to render the plurality of speaker feeds based on the matrix included in the signal value.

6. A method of rendering higher order ambisonic coefficients, the method comprising:

obtaining, by an audio decoding device and from a bitstream that includes an encoded version of the higher order ambisonic coefficients, sparseness information indicative of a sparseness of a matrix used to render the higher order ambisonic coefficients to generate a plurality of speaker feeds, and value symmetry information that indicates value symmetry of the matrix;

based on the value symmetry information and the sparseness information, extract, by the audio decoding device and from the bitstream, a reduced number of bits used to represent the matrix;

based on the value symmetry information, the sparseness information, and the reduced number of bits, reconstruct, by the audio decoding device, the matrix

rendering, by the audio decoding device and using the reconstructed matrix, the higher order ambisonic coefficients to the plurality of speaker feeds; and

outputting, by the audio decoding device, to one or more loudspeaker feeds to drive one or more loudspeakers of the audio decoding device.

7. The method of claim 6 , further comprising determining a speaker layout for which the matrix is to be used to render the plurality of speaker feeds from the higher order ambisonic coefficients.

8. The method of claim 6 , further comprising reproducing a soundfield represented by the higher order ambisonic coefficients based on the plurality of speaker feeds.

9. The method of claim 6 , further comprising obtaining audio rendering information indicative of a signal value identifying an audio renderer used when generating the plurality of speaker feeds; and

rendering the plurality of speaker feeds based on the audio rendering information.

10. The method of claim 9 ,

wherein the signal value includes the matrix used to render the higher order ambisonic coefficients to the plurality of speaker feeds, and

wherein the method further comprises rendering the plurality of speaker feeds based on the matrix included in the signal value.

11. A device configured to produce a bitstream, the device comprising:

a microphone configured to capture a soundfield;

a memory configured to store a matrix; and

one or more processors coupled to the memory, and configured to:

obtain sparseness information indicative of a sparseness of the matrix used to render higher order ambisonic coefficients to generate a plurality of speaker feeds, the higher order ambisonic coefficients representative of the soundfield captured by the microphone;

obtain value symmetry information that indicates value symmetry of the matrix;

based on the value symmetry information and the sparseness information, determine a reduce a number of bits used to represent the matrix; and

generate the bitstream to include an encoded version of the higher order ambisonic coefficients, the value symmetry information, the sparseness information, and the reduced number of bits.

12. The device of claim 11 , wherein the one or more processors are further configured to determine a speaker layout for which the matrix is to be used to render the plurality of speaker feeds from the higher order ambisonic coefficients.

13. The device of claim 11 , further comprising a microphone configured to capture a soundfield represented by the higher order ambisonic coefficients.

14. A method of producing a bitstream, the method comprising:

capturing, by a microphone of an audio encoding device, a soundfield;

obtaining, by the audio encoding device, sparseness information indicative of a sparseness of a matrix used to render higher order ambisonic coefficients to generate a plurality of speaker feeds, the higher order ambisonic coefficients representative of the soundfield captured by the microphone;

obtaining, by the audio encoding device, value symmetry information that indicates value symmetry of the matrix;

based on the value symmetry information and the sparseness information, reducing, by the audio encoding device, a number of bits used to represent the matrix; and

generating, by the audio encoding device, the bitstream to include an encoded version of the higher order ambisonic coefficients, the value symmetry information, the sparseness information, and the reduced number of bits.

15. The method of claim 14 , further comprising determining a speaker layout for which the matrix is to be used to render the plurality of speaker feeds from the higher order ambisonic coefficients.

16. The method of claim 14 , further comprising capturing a soundfield represented by the higher order ambisonic coefficients.