Obtaining sparseness information for higher order ambisonic audio renderers

A method of reconstructing a matrix to render a plurality of speaker feeds, 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 the matrix used to render the plurality of speaker feeds, and value symmetry information that indicates value symmetry of the matrix;
• obtaining from the bitstream, by the audio decoding device, and based on the value symmetry information and the sparseness information, an indication of a number of bits used to represent the matrix;
• based on the value symmetry information, the sparseness information, and the indication of the number of bits, reconstructing, by the audio decoding device, the matrix;
• and
• outputting, by the audio decoding device, the reconstructed matrix and the plurality of speaker feeds.

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

• a memory configured to store a matrix used to render a plurality of speaker feeds;
• 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 the plurality of speaker feeds;
• obtain value symmetry information that indicates value symmetry of the matrix;
• compress the matrix based on the value symmetry information, and the value symmetry information;
• obtain an indication of a number of bits used to represent the compressed matrix;
• specify, in the bitstream, the sparseness information, the value symmetry information, the indication of a number of bits, and an encoded version of higher order ambisonic coefficients.

A method of producing a bitstream, the method comprising:

• obtaining, by an audio encoding device, sparseness information indicative of a sparseness of a matrix used to render a plurality of speaker feeds;
• obtaining, by the audio encoding device, value symmetry information that indicates value symmetry of the matrix;
• compressing, by the audio encoding device, the matrix based on the value symmetry information, and the value symmetry information;
• obtaining, by the audio encoding device, an indication of a number of bits used to represent the compressed matrix;
• specify, by the audio encoding device and in the bitstream, the sparseness information, the value symmetry information, the indication of a number of bits, and an encoded version of higher order ambisonic coefficients.