64 results about "Ambisonics" patented technology

A method for generating loudspeaker signals associated with a target screen size is disclosed. The method includes receiving a bit stream containing encoded higher order ambisonics signals, the encoded higher order ambisonics signals describing a sound field associated with a production screen size. The method further includes decoding the encoded higher order ambisonics signals to obtain a first set of decoded higher order ambisonics signals representing dominant components of the sound field and a second set of decoded higher order ambisonics signals representing ambient components of the sound field. The method also includes combining the first set of decoded higher order ambisonics signals and the second set of decoded higher order ambisonics signals to produce a combined set of decoded higher order ambisonics signals.

A time-of-flight (TOF) array including a plurality of cameras is positioned with a coplanar Higher Order Ambisonics (HOA) array including a plurality of microphones above a target area such as a room or space for analyzing speaker activity in that area. The HOA microphone array iteratively samples sound energy level frames captured by the microphones to identify a sound vector associated with the global maximum energy level in the sound energy level frame. This sound vector is fused with the data from the TOF camera array that identified the positions of sound sources in the target area to associate produced sound corresponding with the sound vector with a physical active sound source in the target area. A beamformer can then be used to save audio corresponding to the sound vector and discard audio not associated with the sound vector to produce a sound recording associated with the active sound source.

A method and apparatus for decompressing a Higher Order Ambisonics (HOA) signal representation is disclosed. The apparatus includes an input interface that receives an encoded directional signal and an encoded ambient signal and an audio decoder that perceptually decodes the encoded directional signal and encoded ambient signal to produce a decoded directional signal and a decoded ambient signal, respectively. The apparatus further includes an extractor for obtaining side information related to the directional signal and an inverse transformer for converting the decoded ambient signal from a spatial domain to an HOA domain representation of the ambient signal. The apparatus also includes a synthesizer for recomposing a Higher Order Ambisonics (HOA) signal from the HOA domain representation of the ambient signal and the decoded directional signal. The side information includes a direction of the directional signal selected from a set of uniformly spaced directions.

Methods and apparatus for acquiring and encoding omnidirectional surround sound are described herein. An exemplary omnidirectional surround microphone may include a first microphone capsule oriented substantially toward a first vertex of a conceptual tetrahedron, a second microphone capsule oriented substantially toward a second vertex of the conceptual tetrahedron, a third microphone capsule oriented substantially toward a third vertex of the conceptual tetrahedron and a fourth microphone capsule oriented substantially toward a fourth vertex of the conceptual tetrahedron.

The present document relates to a method of layered encoding of a frame of a compressed higher-order Ambisonics, HOA, representation of a sound or sound field. The compressed HOA representation comprises a plurality of transport signals. The method comprises assigning the plurality of transport signals to a plurality of hierarchical layers, the plurality of layers including a base layer and one or more hierarchical enhancement layers, generating, for each layer, a respective HOA extension payload including side information for parametrically enhancing a reconstructed HOA representation obtainable from the transport signals assigned to the respective layer and any layers lower than the respective layer, assigning the generated HOA extension payloads to their respective layers, and signaling the generated HOA extension payloads in an output bitstream. The present document further relates to a method of decoding a frame of a compressed HOA representation of a sound or sound field, an encoder and a decoder for layered coding of a compressed HOA representation, and a data structure representing a frame of a compressed HOA representation of a sound or sound field.

A decoding side method for spatial audio rendering using metadata, the method comprising: decoding a plurality of audio objects, a plurality of channels, or a high order ambisonics HOA representation

Higher Order Ambisonics represents three-dimensional sound independent of a specific loudspeaker set-up. However, transmission of an HOA representation results in a very high bit rate. Therefore, compression with a fixed number of channels is used, in which directional and ambient signal components are processed differently. The ambient HOA component is represented by a minimum number of HOA coefficient sequences. The remaining channels contain either directional signals or additional coefficient sequences of the ambient HOA component, depending on what will result in optimum perceptual quality. This processing can change on a frame-by-frame basis.

To provide a method and a device for compressing and decompressing higher-order ambisonics (HOA) representations for sound fields.SOLUTION: A method involves: perceptually decoding compressed dominant directional signals and compressed residual component signals to supply decompressed time-domain signals that represent HOA components of decompressed dominant directional signals and residuals within a spatial domain; re-correlating the decompressed time-domain signal to obtain the corresponding lower-order residual HOA components; determining the decompressed residual HOA components based on the corresponding lower-order residual HOA components; determining predicted directional signals; and determining HOA sound field representation based on the decompressed dominant directional signals, the predicted directional signals, and the decompressed residual HOA components.SELECTED DRAWING: Figure 2a

The invention relates to a panoramic sound space sound image positioning precision analysis method and device and electronic equipment. Comprising the following steps: determining sound image positioning positions, and acquiring an audio signal when a preset test audio is played at each sound image positioning position by using a head simulation audio acquisition device to obtain an audio signal pair of each sound image positioning position; calculating a time difference value and a sound pressure difference value of each position, and calculating an autopower spectrum of each audio signal pair by using Fourier transform; and carrying out region division on the spatial position and determining a weight, and obtaining a positioning precision analysis result according to a time difference value, a sound pressure difference value, a first autopower spectrum and a second autopower spectrum of each sound image positioning position and four parameter results of each position in a corresponding position in the ideal observer model. Therefore, the problems of consumption of a large amount of manpower and time cost, low precision, large result discreteness, difficulty in reproduction and the like in related technologies are solved, the influence of human subjective factors is eliminated, and the result has consistency, objectivity, stability and reproducibility.

An apparatus includes a memory configured to store first audio data and second audio data. The device also includes one or more processors coupled to the memory and configured to determine priorities of audio sources of the audio scene. The one or more processors are further configured to render the first audio data using the object renderer to generate a first audio signal. The first audio data represents a first audio source associated with a first priority. The one or more processors are further configured to render the second audio data using the first Ambisonics renderer to generate a second audio signal. The second audio data represents a second audio source associated with a second priority.

Dynamic range control (DRC) cannot be simply applied to higher-order ambisonics (HOA) based signals. [Solution] A method for performing DRC on an HOA signal includes converting the HOA signal to the spatial domain, analyzing the converted HOA signal, and obtaining a gain factor usable for dynamic compression from the results of the analysis. The gain factor can be transmitted together with the HOA signal. When DRC is applied, the HOA signal is converted to the spatial domain, the gain factor is extracted, and in the spatial domain, it is multiplied with the converted HOA signal to obtain a gain-compensated converted HOA signal. The gain-compensated converted HOA signal is converted back to the original HOA domain to obtain a gain-compensated HOA signal.

The present document relates to a method of layered encoding of a frame of a compressed higher-order Ambisonics, HOA, representation of a sound or sound field. The compressed HOA representation comprises a plurality of transport signals. The method comprises assigning the plurality of transport signals to a plurality of hierarchical layers, the plurality of layers including a base layer and one or more hierarchical enhancement layers, generating, for each layer, a respective HOA extension payload including side information for parametrically enhancing a reconstructed HOA representation obtainable from the transport signals assigned to the respective layer and any layers lower than the respective layer, assigning the generated HOA extension payloads to their respective layers, and signaling the generated HOA extension payloads in an output bitstream. The present document further relates to a method of decoding a frame of a compressed HOA representation of a sound or sound field, an encoder and a decoder for layered coding of a compressed HOA representation, and a data structure representing a frame of a compressed HOA representation of a sound or sound field.

The present document describes a method (400) for rendering an ambisonics signal using a loudspeaker arrangement comprising S loudspeakers. The method (400) comprises converting (401) a set of N ambisonics channel signals (111) into a set of unfiltered pre-rendered signals (211), with N>1 and S>1. Furthermore, the method (400) comprises performing (402) near field compensation, referred to as NFC, filtering of M unfiltered pre-rendered signals (211) of the set of unfiltered pre-rendered signals (211) to provide a set of S filtered loudspeaker channel signals (114) for rendering using the corresponding S loudspeakers.

The invention improves HOA sound field representation compression. The HOA representation is analysed for the presence of dominant sound sources and their directions are estimated. Then the HOA representation is decomposed into a number of dominant directional signals and a residual component. This residual component is transformed into the discrete spatial domain in order to obtain general plane wave functions at uniform sampling directions, which are predicted from the dominant directional signals. Finally, the prediction error is transformed back to the HOA domain and represents the residual ambient HOA component for which an order reduction is performed, followed by perceptual encoding of the dominant directional signals and the residual component.

Methods and apparatus for decoding a compressed Higher Order Ambisonics (HOA) representation of a sound or soundfield. The method may include receiving a bit stream containing the compressed HOA representation and decoding, based on a determination that there are multiple layers, the compressed HOA representation from the bitstream to obtain a sequence of decoded HOA representations. A first subset of the sequence of decoded HOA representations is determined based only on corresponding ambient HOA components. A second subset of the sequence of decoded HOA representations is determined based on corresponding ambient HOA components and corresponding predominant sound components.

To provide a method and apparatus for improving the higher order ambisonics (HOA) compression.SOLUTION: An HOA compression method uses a given number of channels to separately process a directional signal component and an ambient signal component in the given number of channels. An ambient HOA component is expressed by a minimum number of HOA coefficient sequences. The remaining channels contain directional signals or additional coefficient sequences of the ambient HOA component depending on whether an optimal perception quality is yielded. The process can be changed in a frame unit.SELECTED DRAWING: Figure 1

A spatial audio restoration device of an embodiment includes a video feature amount calculation unit that calculates a video feature amount on the basis of video information, an audio feature amount calculation unit that calculates an audio feature amount on the basis of audio information that is a monaural sound corresponding to the video information, and a coefficient calculation unit that calculates a high-order Ambisonics coefficient on the basis of the video feature amount and the audio feature amount.

A technique for encoding Ambisonics audio includes inputting audio to multiple Ambisonics encoders producing respective Ambisonics soundfields. Prior to mixing the soundfields, each soundfield is weighted to mitigate artifacts from order-truncation. After weighting, the soundfields are mixed to produce Ambisonics audio.

Disclosed is a hierarchical spatial resolution codec that adaptively adjusts the representations of immersive audio content as the target bandwidth for delivering the audio content changes. The audio content may be represented by an adaptive number of content types such as channels / objects, higher-order ambisonics (HOA), and encoded by adaptive spatial coding techniques to support the target bitrate of a transmission channel or user. Adaptive spatial coding techniques may include adaptive channel / object spatial encoding techniques to generate an adaptive number of channels / objects, and adaptive HOA spatial encoding or HOA compression techniques to generate an adaptive order of the HOA. The adaptation may be a function of the target bitrate that is associated with a desired quality, and an analysis that determines the priority of the channels, objects, and HOA. High priority channels / objects may be encoded into a high quality bit-stream while low priority channels / objects may be converted and encoded as HOA.

Decoding of Ambisonics representations for a stereo loudspeaker setup is known for first-order Ambisonics audio signals. But such first-order Ambisonics approaches have either high negative side lobes or poor localisation in the frontal region. The invention deals with the processing for stereo decoders for higher-order Ambisonics HOA. The desired panning functions can be derived from a panning law for placement of virtual sources between the loudspeakers. For each loudspeaker a desired panning function for all possible input directions at sampling points is defined. The panning functions are approximated by circular harmonic functions, and with increasing Ambisonics order the desired panning functions are matched with decreasing error. For the frontal region between the loudspeakers, a panning law like the tangent law or vector base amplitude panning (VBAP) are used. For the rear directions panning functions with a slight attenuation of sounds from these directions are defined.

The invention discloses a three-dimensional space sound playback method for a layered loudspeaker array. The three-dimensional space sound playback method comprises the following steps: presetting space coordinates of each unit of the loudspeaker array and a target virtual sound source; layering the loudspeaker array according to an elevation angle, calculating a two-dimensional Ambisonics decoding matrix for each layer of loudspeaker array, combining every two adjacent loudspeaker layers, and calculating an amplitude modulation inverse matrix; according to the elevation angle of the target virtual sound source, amplitude modulation coefficients of the loudspeaker layers combined in pairs are calculated, and effective loudspeaker layers are selected for playback; and synthesizing two virtual sources in the effective loudspeaker layer according to the azimuth angle of the target sound source, and synthesizing a three-dimensional virtual sound source in combination with horizontal azimuth angle decoding and amplitude modulation coefficients. According to the method, the playback precision of the area with the actual loudspeaker, especially the horizontal area, can be improved, and the requirements of the algorithm on the number of non-horizontal loudspeakers and the spatial uniformity are reduced.

A sound scene is represented as first order Ambisonics (FOA) audio. A processor formats each signal of the FOA audio to a stream of audio frames, provides the formatted FOA audio to a machine learning model that reformats the formatted FOA audio in a target or desired higher order Ambisonics (HOA) format, and obtains output audio of the sound scene in the desired HOA format from the machine learning model. The output audio in the desired HOA format may then be rendered according to a playback audio format of choice. Other aspects are also described and claimed.

To provide a method and apparatus for decoding an Ambisonics audio soundfield representation for audio playback using a 2D setup.SOLUTION: For decoding, a decode matrix specific to the given loudspeaker setup is needed, which is generated using the known loudspeaker positions. A method for decoding an encoded audio signal in a sound field format for L loudspeakers at known positions comprises the steps of adding 10 at least one virtual loudspeaker position to the L loudspeaker positions, generating 11 a 3D decoding matrix D ', downmixing 12 said 3D decoding matrix D ', and decoding 14 the encoded audio signal 3D using the downscaled i14 decoding matrix to obtain a plurality of decoded loudspeaker signals q14.SELECTED DRAWING: Figure 1

Conventional audio compression technologies perform a standardized signal transformation, independent of the type of the content. Multi-channel signals are decomposed into their signal components, subsequently quantized and encoded. This is disadvantageous due to lack of knowledge on the characteristics of scene composition, especially for e.g. multi-channel audio or Higher-Order Ambisonics (HOA) content. A method for decoding an encoded bitstream of multi-channel audio data and associated metadata is provided, including transforming the first Ambisonics format of the multi-channel audio data to a second Ambisonics format representation of the multi-channel audio data, wherein the transforming maps the first Ambisonics format of the multi-channel audio data into the second Ambisonics format representation of the multi-channel audio data. A method for encoding multi-channel audio data that includes audio data in an Ambisonics format, wherein the encoding includes transforming the audio data in an Ambisonics format into encoded multi-channel audio data is also provided.

To provide a method and an apparatus for decoding a stereo loudspeaker signal from a Higher Order Ambisonics (HOA) audio signal that achieves a good orientation in a forward direction and small negative sidelobes.SOLUTION: A method includes: a step 51 of calculating panning function to be desired which receives values of azimuth angles φL and φR of left and right loudspeakers and the number S of virtual sampling points, and calculates a matrix G comprising the panning function value to be described of all virtual sampling points; a step 52 of conducting the derives an order N from an Ambisonics signal a(t), calculates a mode matrix Z from the number S and the order N, and calculates a pseudo-inverse matrix +Z+ of the matrix Z; a step 53 of calculating mode matrix Ξ frim the number S and the order N; and a step 54 of calculating a pseudo-inverse matrix Ξ+ of the matrix Ξ. In a step 55, a decoding matrix D from the matrix G and a Ξ+ is calculated, and in a step 56, a loudspeaker signal l(t) is calculated from the Ambisonics signal a(t) by using the decoding matrix D.SELECTED DRAWING: Figure 5

A software of the present invention causes a processor to execute a process including converting an A format signal applicable to ambisonics to a B format signal; distinguishing a specific direction from a plurality of directions based on the B format signal; and generating and outputting an audio signal corresponding to the specific direction. Also disclosed is a microphone including the software.

To provide a method and an apparatus for rendering a Higher Order Ambisonics (HOA) format audio representation for any loudspeaker setup.SOLUTION: A method for rendering an audio sound field representation for an arbitrary spatial loudspeaker setup includes the steps of obtaining a decoding matrix for rendering to a given arrangement of target loudspeakers by obtaining the number of target speakers and their positions, the positions of a spherical modeling grid and an HOA order, generating a mixing matrix from the positions of the modeling grid and the positions of the speakers, generating a mode matrix from the positions of the spherical modeling grid and the HOA order, calculating a first decoding matrix from the mixing matrix and the mode matrix, and smoothing and scaling the first decoding matrix using smoothing and scaling factors.SELECTED DRAWING: None

Described techniques enable the use of ambisonics encoding / decoding for spatially accurate sound reproduction that is low-latency and that conserves computational and battery resources. Different sounds sources may be encoded using different ambisonics encoding orders, with higher order encoding being used to process sound from a sound source of current attention of a user, and lower order encoding being used to process other sound sources, such as background sound sources.