Abstract: In general, techniques are described for coding of vectors decomposed from higher order ambisonic coefficients. A device comprising a processor and a memory may perform the techniques. The processor may be configured to obtain from a bitstream data indicative of a plurality of weight values that represent a vector that is included in a decomposed version of the plurality of HOA coefficients. Each of the weight values may correspond to a respective one of a plurality of weights in a weighted sum of code vectors that represents the vector and that includes a set of code vectors. The processor may further be configured to reconstruct the vector based on the weight values and the code vectors. The memory may be configured to store the reconstructed vector.

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 directed to intermediate compression of higher order ambisonic audio data. For example, a device comprising a processor and a memory may be configured to perform the techniques. The memory may be configured to store an intermediately formatted audio data generated as a result of an intermediate compression of higher order ambisonic audio data. The one or more processors may be configured to process the intermediately formatted audio data.

Abstract: In general, techniques are described for compression and decoding of audio data are generally disclosed. An example device for compressing audio data includes one or more processors configured to apply a decorrelation transform to ambient ambisonic coefficients to obtain a decorrelated representation of the ambient ambisonic coefficients, the ambient HOA coefficients having been extracted from a plurality of higher order ambisonic coefficients and representative of a background component of a soundfield described by the plurality of higher order ambisonic coefficients, wherein at least one of the plurality of higher order ambisonic coefficients is associated with a spherical basis function having an order greater than one.

Abstract: In general, techniques are described for obtaining spherical harmonic coefficients (SHC). A device comprising a processor and a memory may be configured to perform the techniques. The processor may obtain a set of coefficients of a vector representative a distinct component of a sound field, the vector having been decomposed from SHC representative of the sound field. The processor may obtain a configuration mode by which to extract the coefficients, where the configuration mode indicates that the coefficients include coefficients corresponding to an order greater than an order of a basis function to which one or more of the spherical harmonic coefficients correspond and exclude at least one of the coefficients corresponding to a greater order. The processor may extract the coefficients of the vector based on the obtained configuration mode. The memory may be configured to store the non-zero set of the coefficients of the vector.

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 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 indicating reusability of an index that determines a Huffman codebook used to code data associated with a vector in a spherical harmonics domain. The bitstream may comprise an indicator for whether to reuse, from a previous frame, at least one syntax element indicative of the index. The memory may be configured to store the bitstream.

Abstract: A device comprising a memory and one or more processors may be configured extract, from the bitstream, a type of quantization mode. The one or more processors may also be configured to switch, based on the type of quantization mode, between non-predictive vector dequantization to reconstruct a first set of one or more weights used to approximate the multi-directional V-Vector in the higher order ambisonics domain, and predictive vector dequantization to reconstruct a second set of one or more weights used to approximate the multi-directional V-Vector in the higher order ambisonics domain. The memory may be configured to store the reconstructed first set of one or more weights used to approximate the multi-directional V-Vector in the higher order ambisonics domain, and the reconstructed second set of one or more weights used to approximate the multi-directional V-Vector in the higher order ambisonics domain.

Abstract: In general, techniques are described for obtaining decomposed versions of spherical harmonic coefficients. A device comprising a processor and a memory may be configured to perform the techniques. The processor may obtain a non-zero set of coefficients of a vector representative a distinct component of a sound field. The vector may have been decomposed from a plurality of spherical harmonic coefficients that describe the sound field. The processor may also obtain one of a plurality of configuration modes by which to extract the non-zero set of coefficients of the vector, where the one of the configuration modes indicates that the coefficients include all of the coefficients except for at least one of the coefficients. The processor may further extract the coefficients of the vector based on the obtained one of the configuration modes. The memory may be configured to store the non-zero set of the coefficients of the vector.

Abstract: In general, techniques are described for indicating reuse of a syntax element that indicates a quantization mode used when compressing a vector. A device comprising a processor and a memory may perform the techniques. The processor may be configured to obtain a bitstream comprising a vector 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 a quantization mode used when compressing the vector. The memory may be configured to store the bitstream.

Abstract: In general, techniques are described for indicating reuse of a syntax element indicating a vector quantization codebook used in compressing a vector. A device comprising a processor and a memory may perform the techniques. The processor may be configured to obtain a bitstream comprising a vector in a spherical harmonics domain. The bitstream may further comprise an indicator for whether to reuse, from a previous frame, a syntax element indicative of a vector quantization codebook used when compressing the vector. The memory may be configured to store the bitstream.

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: In general, techniques are described for audio editing of higher-order ambisonic audio data. 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 higher order ambisonic (HOA) representation of the audio object. The one or more processors may be configured to add a source tail to the HOA representation of the audio object by storing one or more spherical harmonic (SH) basis functions associated with the audio object to a buffer.

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 and devices are described for motion compensation. An example a device configured to compensate motion. The device includes a memory configured to store audio data associated with a three-dimensional (3D) soundfield and one or more processors. The one or more processors are configured to receive motion information indicating one or more movements associated with a capture of one or more audio objects of a three-dimensional (3D) soundfield by a microphone array, and to adjust virtual positioning information associated with one or more microphones of a microphone array to compensate one or more movements associated with a capture of one or more audio objects of the 3D soundfield by the microphone array. The one or more processors may also be configured to generate a motion-compensated bitstream based on the adjusted virtual positioning information.

Abstract: In general, techniques are described for obtaining audio rendering information in a bitstream. A device configured to render higher order ambisonic coefficients comprising a processor and a memory may perform the techniques. The processor may be configured to obtain sparseness information indicative of a sparseness of a matrix used to render the higher order ambisonic coefficients to a plurality of speaker feeds. The memory may be configured to store the sparseness information.

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: 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 coding a number of code vectors for independent frame of higher order ambisonic coefficients. An audio decoding device comprising a memory and a processor may perform the techniques. The memory may store a first frame of a bitstream and a second frame of the bitstream. The processor may extract, from the first frame, one or more bits indicative of whether the first frame is an independent frame that includes information specifying a number of code vectors to be used when performing vector dequantization with respect to the vector. The processor may also extract, from the first frame without referencing the second frame, the information specifying the number of code vectors.