Abstract: In general, techniques are described for indicating frame parameter reusability for decoding vectors. A device comprising a processor and a memory may perform the techniques. The processor may be configured to obtain a bitstream comprising a vector representative of an orthogonal spatial axis in a spherical harmonics domain. The bitstream may further comprise an indicator for whether to reuse, from a previous frame, at least one syntax element indicative of information used when compressing the vector. The memory may be configured to store the bitstream.

Abstract: In general, techniques are described for compressing higher order ambisonics (HOA) audio data. 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 plurality of spherical harmonic coefficients from a plurality of near field compensated spherical harmonic coefficients by, at least in part, counterbalancing application of a near field compensation filter to the plurality of spherical harmonic coefficients.

Abstract: In general, techniques are described for coding of spherical harmonic coefficients representative of a three dimensional soundfield. A device comprising a memory and one or more processors may be configured to perform the techniques. The memory may be configured to store a plurality of spherical harmonic coefficients. The one or more processors may be configured to perform an energy analysis with respect to the plurality of spherical harmonic coefficients to determine a reduced version of the plurality of spherical harmonic coefficients.

Abstract: In general, techniques are described for obtaining decomposed versions of spherical harmonic coefficients. A device comprising one or more processors may be configured to perform the techniques, whereby the processors may be configured to obtain, from a bitstream, at least one of one or more vectors decomposed from spherical harmonic coefficients that were recombined with background spherical harmonic coefficients, wherein the spherical harmonic coefficients describe a sound field, and wherein the background spherical harmonic coefficients described one or more background components of the same sound field.

Abstract: In general, techniques are described for performing an interpolation with respect to decomposed versions of a sound field. A device comprising one or more processors may be configured to perform the techniques. The processors may be configured to obtain decomposed interpolated spherical harmonic coefficients for a time segment by, at least in part, performing an interpolation with respect to a first decomposition of a first plurality of spherical harmonic coefficients and a second decomposition of a second plurality of spherical harmonic coefficients.

Abstract: In general, techniques are described for performing a positional analysis to code audio data. Typically, this audio data comprises a hierarchical representation of a soundfield and may include, as one example, spherical harmonic coefficients (which may also be referred to as higher-order ambisonic coefficients). An audio compression device that includes one or more processors may perform the techniques. The processors may be configured to allocate bits to one or more portions of the audio data, at least in part by performing positional analysis on the audio data.

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: 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 identifying distinct audio objects from spherical harmonic coefficients (which may also be denotes as higher order ambisonic coefficients). A device comprising one or more processors may perform the techniques so as to identify the distinct audio objects from the spherical harmonic coefficients (SHC) associated with the audio objects based on a directionality determined for one or more of the audio objects.

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 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: A device comprising one or more processors is configured to obtain transformation information, the transformation information describing how a sound field was transformed to reduce a number of a plurality of hierarchical elements to a reduced plurality of hierarchical elements; and perform binaural audio rendering with respect to the reduced plurality of hierarchical elements based on the transformation information.

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 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 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 performing order reduction with respect to a plurality of spherical harmonic coefficients. In accordance with the techniques, a device comprising one or more processors may be configured to perform, based on a target bitrate, order reduction with respect to a plurality of spherical harmonic coefficients or decompositions thereof to generate reduced spherical harmonic coefficients or the reduced decompositions thereof, wherein the plurality of spherical harmonic coefficients represent a sound field.

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 mapping virtual speakers to physical speakers, having first adjusted the position of one of the virtual speakers based on a relative position of the one of the virtual speakers to one of the physical speakers. A device comprising one or more processors may perform the techniques. The one or more processors may be configured to determine a difference in position between one of a plurality of physical speakers and one of a plurality of virtual speakers arranged in a geometry, and adjust a position of the one of the plurality of virtual speakers within the geometry based on the determined difference in position and prior to mapping the plurality of virtual speakers to the plurality of physical speakers.

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.