Abstract: In general, techniques are described for determining quantization step sizes for compression of spatial components of a sound field. A device comprising one or more processors may be configured to perform the techniques. In other words, the one or more processors may be configured to determine a quantization step size to be used when compressing a spatial component of a sound field, where the spatial component generated by performing a vector based synthesis with respect to a plurality of spherical harmonic coefficients.

Abstract: A device comprising one or more processors is configured to determine a plurality of segments for each of a plurality of binaural room impulse response filters, wherein each of the plurality of binaural room impulse response filters comprises a residual room response segment and at least one direction-dependent segment for which a filter response depends on a location within a sound field; transform each of at least one direction-dependent segment of the plurality of binaural room impulse response filters to a domain corresponding to a domain of a plurality of hierarchical elements to generate a plurality of transformed binaural room impulse response filters, wherein the plurality of hierarchical elements describe a sound field; and perform a fast convolution of the plurality of transformed binaural room impulse response filters and the plurality of hierarchical elements to render the sound field.

Abstract: In general, techniques are described for obtaining an indication of whether spherical harmonic coefficients are representative of a synthetic audio object. In accordance with the techniques, a device comprising one or more processors may be configured to obtain an indication of whether spherical harmonic coefficients representative of a sound field are generated from a synthetic audio object.

Abstract: A device comprises one or more processors configured to apply a binaural room impulse response filter to spherical harmonic coefficients representative of a sound field in three dimensions so as to render the sound field.

Abstract: In general, techniques are described for compensating for error in decomposed representations of sound fields. In accordance with the techniques, a device comprising one or more processors may be configured to quantize one or more first vectors representative of one or more components of a sound field, and compensate for error introduced due to the quantization of the one or more first vectors in one or more second vectors that are also representative of the same one or more components of the sound field.

Abstract: In general, techniques are described for obtaining one or more first vectors describing distinct components of a soundfield and one or more second vectors describing background components of the soundfield, both the one or more first vectors and the one or more second vectors generated at least by performing a transformation with respect to a plurality of spherical harmonic coefficients.

Abstract: In general, techniques are described for identifying a codebook to be used when compressing spatial components of a sound field. A device comprising one or more processors may be configured to perform the techniques. The one or more processors may be configured to identify a Huffman codebook to use when compressing a spatial component of a plurality of spatial components based on an order of the spatial component relative to remaining ones of the plurality of spatial components, the spatial component generated by performing a vector based synthesis with respect to a plurality of spherical harmonic coefficients.

Abstract: In general, techniques are described for obtaining decomposed versions of spherical harmonic coefficients. In accordance with these techniques, a device comprising one or more processors may be configured to determine a first non-zero set of coefficients of a vector that represent a distinct component of a sound field, the vector having been decomposed from a plurality of spherical harmonic coefficients that describe the sound field.

Abstract: In general, techniques are described for compressing decomposed representations of a sound field. A device comprising one or more processors may be configured to perform the techniques. The one or more processors may be configured to obtain a bitstream comprising a compressed version of a spatial component of a sound field, the spatial component generated by performing a vector based synthesis with respect to a plurality of spherical harmonic coefficients.

Abstract: In general, techniques are described for performing a vector-based synthesis with respect to higher order ambisonic coefficients (or, in other words, spherical harmonic coefficients). A device comprising a processor may be configured to perform the techniques. The processor may perform the vector-based synthesis with respect to spherical harmonic coefficients to generate decomposed representations of the plurality of spherical harmonic coefficients and determine distinct and background directional information from the directional information. The processor may then reduce an order of the directional information associated with the background audio objects to generate transformed background directional information, and apply compensation to increase values of the transformed directional information to preserve an overall energy of the sound field.

Abstract: In general, techniques are described for specifying spherical harmonic coefficients in a bitstream. A device comprising one or more processors may perform the techniques. The processors may be configured to identify, from the bitstream, a plurality of hierarchical elements describing a sound field that are included in the bitstream. The processors may further be configured to parse the bitstream to determine the identified plurality of hierarchical elements.

Abstract: In general, techniques are described for transforming spherical harmonic coefficients. A device comprising one or more processors may perform the techniques. The processors may be configured to parse the bitstream to determine transformation information describing how the sound field was transformed to reduce a number of the plurality of hierarchical elements that provide information relevant in describing the sound field. The processors may further be configured to, when reproducing the sound field based on those of the plurality of hierarchical elements that provide information relevant in describing the sound field, transform the sound field based on the transformation information to reverse the transformation performed to reduce the number of the plurality of hierarchical elements.

Abstract: In general, techniques are described for specifying audio rendering information in a bitstream. A device configured to generate the bitstream may perform various aspects of the techniques. The bitstream generation device may comprise one or more processors configured to specify audio rendering information that includes a signal value identifying an audio renderer used when generating the multi-channel audio content. A device configured to render multi-channel audio content from a bitstream may also perform various aspects of the techniques. The rendering device may comprise one or more processors configured to determine audio rendering information that includes a signal value identifying an audio renderer used when generating the multi-channel audio content, and render a plurality of speaker feeds based on the audio rendering information.

Abstract: In general, techniques are described for determining renderers used for rendering spherical harmonic coefficients to generate one or more loudspeaker signals. A device comprising one or more processors may perform the techniques. The one or more processors may be configured to determine a local speaker geometry of one or more speakers used for playback of spherical harmonic coefficients representative of a sound field, and configure the device to operate based on the local speaker geometry.

Abstract: Systems, methods, and apparatus for a unified approach to encoding different types of audio inputs are described.

Abstract: In general, techniques are described for grouping audio objects into clusters. In some examples, a device for audio signal processing comprises a cluster analysis module configured to group, based on spatial information for each of N audio objects, a plurality of audio objects that includes the N audio objects into L clusters, where L is less than N, wherein the cluster analysis module is configured to receive information from at least one of a transmission channel, a decoder, and a renderer, and wherein a maximum value for L is based on the information received. The device also comprises a downmix module configured to mix the plurality of audio objects into L audio streams, and a metadata downmix module configured to produce, based on the spatial information and the grouping, metadata that indicates spatial information for each of the L audio streams.

Abstract: Systems, methods, and apparatus for grouping audio objects into clusters are described.

Abstract: In general, techniques are described for grouping audio objects into clusters. In some examples, a device for audio signal processing comprises a cluster analysis module configured to, based on a plurality of audio objects, produce a first grouping of the plurality of audio objects into L clusters, wherein the first grouping is based on spatial information from at least N among the plurality of audio objects and L is less than N. The device also includes an error calculator configured to calculate an error of the first grouping relative to the plurality of audio objects, wherein the error calculator is further configured to, based on the calculated error, produce a plurality L of audio streams according to a second grouping of the plurality of audio objects into L clusters that is different from the first grouping.

Abstract: Systems, methods, and apparatus for a unified approach to encoding different types of audio inputs are described.

Abstract: Systems, methods, and apparatus for backward-compatible coding of a set of basis function coefficients that describe a sound field are presented.