Abstract: Systems and techniques for rendering audio data are generally disclosed. An example device for rendering a higher order ambition (HOA) audio signal includes a memory configured to store the HOA audio signal, and one or more processors coupled to the memory. The one or more processors are configured to perform a loudness compensation process as part of generating an effect matrix. The one or more processors are further configured to render the HOA audio signal based on the effect matrix.

Abstract: In general, techniques are described for coding higher-order ambisonic coefficients during multiple transitions. A device comprising a processor and a memory coupled to the processor may be configured to perform the techniques. The processor may be configured to obtain a multi-transition indication of whether an ambient HOA coefficient is in transition during a same frame of the bitstream as a foreground audio signal is in transition. The processor may also be configured to obtain a vector that describes a spatial characteristic of a corresponding foreground audio signal based on the multi-transition indication, both the vector and the corresponding HOA audio signal decomposed from the HOA audio data. The memory may be configured to store the vector.

Abstract: In general, techniques are described for coding of vectors decomposed from higher-order ambisonic coefficients. A device comprising a memory and a processor may perform the techniques. The memory may be configured to store audio data. The processor may be configured to determine whether to perform vector dequantization or scalar dequantization with respect to a decomposed version of the plurality of HOA coefficients.

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 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 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.

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: In general, techniques are described for 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 spherical harmonic (SH) basis functions. The one or more processors may be configured to manipulate the SH basis functions associated with higher order ambisonics coefficients to alter a direction of an audio object represented by the higher order ambisonics coefficients.

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 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 coding an ambient higher order ambisonic coefficient. 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 obtain, from the first frame, one or more bits indicative of whether the first frame is an independent frame that includes additional reference information to enable the first frame to be decoded without reference to the second frame. The processor may further obtain, in response to the one or more bits indicating that the first frame is not an independent frame, prediction information for first channel side information data of a transport channel. The prediction information may be used to decode the first channel side information data of the transport channel with reference to second channel side information data of the transport channel.

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 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: 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 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 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: 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 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: 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.