Projection-based audio coding
AssigneeGoogle Inc.
InventorsJan SKOGLUND, Michael GRACZYK
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Abstract
Techniques of performing ambisonic coding involve coupling channels of a high-order ambisonics (HOA) signal using a projection matrix based on positions of a set of loudspeakers on a unit sphere to form a projected HOA signal. Each pair of components of the projected HOA signal may then be encoded into a stereo format. In some arrangements, the projection matrix may be based on a decoding or demixing matrix that is in turn based on spherical harmonics evaluated at specified loudspeaker positions. In this way, the encoding efficiency (e.g., bitrate for a given sound quality) is improved over the conventional approaches to performing ambisonic coding.
Claims20
A method, comprising:
- receiving, by processing circuitry of a server computing device configured to encode high-order ambisonic (HOA) audio data having a specified number of channels, loudspeaker data indicating positions of a plurality of loudspeakers with respect to a listener;
- generating, by the processing circuitry, projection matrix data representing a projection matrix, the projection matrix being based on the loudspeaker data and the specified number of channels;
- receiving, by the processing circuitry, HOA audio data having the specified number of channels;
- performing, by the processing circuitry, a projection operation on the HOA audio data and the projection matrix data to produce a projected HOA signal, the projected HOA signal having a plurality of components;
- and
- arranging, by the processing circuitry, pairs of components of the projected HOA signal into coupled streams in a stereo format.
A computer program product comprising a nontransitive storage medium, the computer program product including code that, when executed by processing circuitry of a server computing device configured to encode high-order ambisonic (HOA) audio data having a specified number of channels, causes the processing circuitry to perform a method, the method comprising:
- receiving loudspeaker data indicating positions of a plurality of loudspeakers with respect to a listener;
- generating projection matrix data representing a projection matrix, the projection matrix being based on the loudspeaker data and the specified number of channels;
- receiving HOA audio data having the specified number of channels;
- performing a projection operation on the HOA audio data and the projection matrix data to produce a projected HOA signal, the projected HOA signal having a plurality of components;
- and
- arranging pairs of components of the projected HOA signal into coupled streams in a stereo format.
An electronic apparatus configured to encode high-order ambisonic (HOA) audio data having a specified number of channels, the electronic apparatus comprising:
- memory;
- and
- controlling circuitry coupled to the memory, the controlling circuitry being configured to:
- receive loudspeaker data indicating positions of a plurality of loudspeakers with respect to a listener;
- generate projection matrix data representing a projection matrix, the projection matrix being based on the loudspeaker data and the specified number of channels;
- receive HOA audio data having the specified number of channels;
- perform a projection operation on the HOA audio data and the projection matrix data to produce a projected HOA signal, the projected HOA signal having a plurality of components;
- and
- arrange pairs of components of the projected HOA signal into coupled streams in a stereo format.
Dependencies are inferred from the claim text.