Abstract: In general, techniques are described for signaling layers for scalable coding of higher order ambisonic audio data. A device comprising a memory and a processor may be configured to perform the techniques. The memory may be configured to store the bitstream. The processor may be configured to obtain, from the bitstream, an indication of a number of layers specified in the bitstream, and obtain the layers of the bitstream based on the indication of the number of layers.

Abstract: In general, techniques are described for performing layered intermediate compression for higher order ambisonic (HOA) audio data. A device comprising a memory and a processor may be configured to perform the techniques. The memory may store HOA coefficients of the HOA audio data. The processors may decompose the HOA coefficients into a predominant sound component and a corresponding spatial component. The spatial component may be representative of the directions, shape, and width of the predominant sound component, and defined in the spherical harmonic domain. The processor may specify, in a bitstream conforming to an intermediate compression format, a subset of the HOA coefficients that represent an ambient component. The processor may also specify, in the bitstream and irrespective of a determination of a minimum number of ambient channels and a number of elements to specify in the bitstream for the spatial component, all elements of the spatial component.

Abstract: In general, techniques are described for crossfading sets of spherical harmonic coefficients. An audio encoding device or audio decoding device comprising a memory and a processor may be configured to perform the techniques. The memory may be configured to store a first set of spherical harmonic coefficients (SHCs) and a second set of SHCs. The first set of SHCs describe a first sound field. The second set of SHCs describe a second sound field. The processor may be configured to crossfade between the first set of SHCs and a second set of SHCs to obtain a first set of crossfaded SHCs.

Abstract: In general, techniques are described by which to perform bitrate allocation with respect to higher order ambisonic (HOA) audio data. A device comprising a memory and a processor may be configured to perform various aspects of the bitrate allocation techniques. The memory may be configured to store a spatially compressed version of the HOA audio data. The processor may be coupled to the memory, and configured to perform bitrate allocation, based on an analysis of transport channels representative of the spatially compressed version of the HOA audio data, and prior to performing gain control with respect to the transport channels or after performing inverse gain control with respect to the transport channels, to allocate a number of bits to each of the transport channels. The processor may also be configured to generate a bitstream that specifies each of the transport channels using the respective allocated number of bits.

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: An example audio decoding device includes processing circuitry and a memory device coupled to the processing circuitry. The processing circuitry is configured to receive, in a bitstream, encoded representations of audio objects of a three-dimensional (3D) soundfield, to receive metadata associated with the bitstream, to obtain, from the received metadata, one or more transmission factors associated with one or more of the audio objects, and to apply the transmission factors to the one or more audio objects to obtain parallax-adjusted audio objects of the 3D soundfield. The memory device is configured to store at least a portion of the received bitstream, the received metadata, or the parallax-adjusted audio objects of the 3D soundfield.

Abstract: In general, techniques are described for signaling channels for scalable coding of higher order ambisonic audio data. A device comprising a memory and a processor may be configured to perform the techniques. The memory may be configured to store the bitstream. The processor may be configured to obtain, from the bitstream, an indication of a number of channels specified in one or more layers in the bitstream, and obtain the channels specified in the one or more layers in the bitstream based on the indication of the number of channels.

Abstract: In general, techniques are described for closed loop quantization of HOA coefficients that provide a three-dimensional representation of the sound field. An audio encoding device may perform closed loop quantization of an audio object based at least in part on a result of performing quantization of directional information associated with the audio object. An audio decoding device may obtain an audio object that has been closed loop quantized based at least in part on a result of performing quantization of directional information associated with the audio object, and may dequantize the audio object.

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: This disclosure describes techniques for coding of higher-order ambisonics audio data comprising at least one higher-order ambisonic (HOA) coefficient corresponding to a spherical harmonic basis function having an order greater than one. This disclosure describes techniques for adjusting HOA soundfields to potentially improve spatial alignment of the acoustic elements to the visual component in a mixed audio/video reproduction scenario. In one example, a device for rendering an HOA audio signal includes one or more processors configured to render the HOA audio signal over one or more speakers based on one or more field of view (FOV) parameters of a reference screen and one or more FOV parameters of a viewing window.

Abstract: Methods and apparatuses are disclosed for streaming audio between a source device and a destination device. An example method may include determining an available bandwidth between the source device and the destination device. The example method may also include determining a bit rate for streaming audio from the source device to the destination device, wherein the bit rate is based on the available bandwidth. The example method may further include determining a preferred audio characteristic for streaming audio from the source device to the destination device, wherein the preferred audio characteristic is based on a user preference. The example method may also include determining encoded audio to be transmitted from the source device to the destination device based on the preferred audio characteristic and the bit rate.

Abstract: In general, techniques are described for transitioning an ambient higher order ambisonic coefficient. A device comprising a memory and a processor may be configured to perform the techniques. The processor may obtain, from a frame of a bitstream of encoded audio data, a bit indicative of a reduced vector. The reduced vector may represent, at least in part, a spatial component of a sound field. The processor may also obtain, from the frame, a bit indicative of a transition of an ambient higher-order ambisonic coefficient. The ambient higher-order ambisonic coefficient may represent, at least in part, an ambient component of the sound field. The reduced vector may include a vector element associated with the ambient higher-order ambisonic coefficient in transition. The memory may be configured to store the frame of the bitstream.

Abstract: A method for reducing vibration noise by an electronic device is described. The method includes obtaining an audio signal. The audio signal includes vibration noise. The method also includes obtaining vibration data from one or more motion sensor signals. The method further includes processing the vibration data to produce microphone-response matched vibration data based on a transfer function. The method additionally includes reducing the vibration noise based on the microphone-response matched vibration data.

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 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 sign symmetry information indicative of sign symmetry of a matrix used to render the higher order ambisonic coefficients to generate a plurality of speaker feeds. The memory may be configured to store the sparseness information.

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 directed to performing normalization with respect to ambient higher order ambisonic audio data. A device configured to decode higher order ambisonic audio data may perform the techniques. The device may include a memory and one or more processors. The memory may be configured to store an audio channel that provides a normalized ambient higher order ambisonic coefficient representative of at least a portion of an ambient component of a soundfield. The one or more processors may be configured to perform inverse normalization with respect to the audio channel.

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 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.