91 results about "Ambisonics" patented technology

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.

A device 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 an audio scene. The one or more processors are also configured to render, using an object renderer, the first audio data 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, using a first ambisonics renderer, the second audio data to generate a second audio signal. The second audio data represents a second audio source associated with a second priority.

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.

The present invention belongs to the technical field of spatial sound field playback, and specifically relates to a sound field playback spatial decoding method of high-order Ambisonics based on sparse plane wave decomposition. The method realizes sound field playback through two stages. The first stage pre-acquires the driving function of the loudspeaker system to play back plane waves in different directions, which is called the pre-calculation stage; the second stage performs sparse plane wave decomposition on the target sound field to calculate the playback driving function, which is called the playback decoding stage. The present invention uses the spherical harmonic domain sparse plane wave decomposition method to play back the sound field, and effectively improves the sound field playback accuracy when the target sound field is generated by a small number of sound sources. The method of the present invention is simple and low in cost, and can use the spherical harmonic coefficients of the target sound field with lower orders to achieve higher-precision playback; it has a good computing speed, and the plane wave generator of the playback system can be measured and calculated in advance, and the loudspeaker system drive signal can be quickly obtained in the playback stage; at the same time, a larger optimal listening range is guaranteed.

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

Ambisonics audio such as may be used for computer simulations such as computer games is improved by using multi-order optimizations that frame an optimization problem that minimizes a cost function across a subset of Ambisonics orders for a chosen Ambisonics order “N”. In a simple form, this cost function minimizes error across all orders (0<=n<=N), and additional weighting is applied to emphasize or de-emphasize particular orders. The cost functions and optimization criteria may be different for binaural and speaker outputs.

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 improve coding of side information required for coding a higher order ambisonics representation of a sound field.SOLUTION: Higher order ambisonics represents three-dimensional sound independent of a specific loudspeaker set-up. However, transmission of a 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. For coding, various portions of an original HOA representation are predicted from the directional signal components. This prediction provides side information which is required for corresponding decoding. By using some additional specific purpose bits, known side information coding processing is improved in that the required number of bits for coding that side information is reduced on average.SELECTED DRAWING: Figure 1

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.

Soundfield signals such as e.g. Ambisonics carry a representation of a desired sound field. The Ambisonics format is based on spherical harmonic decomposition of the soundfield, and Higher Order Ambisonics (HOA) uses spherical harmonics of at least 2nd order. However, commonly used loudspeaker setups are irregular and lead to problems in decoder design. A method for improved decoding an audio soundfield representation for audio playback comprises calculating a panning function (W) using a geometrical method based on the positions of a plurality of loudspeakers and a plurality of source directions, calculating a mode matrix (Ξ) from the loudspeaker positions, calculating a pseudo-inverse mode matrix (Ξ+) and decoding the audio soundfield representation. The decoding is based on a decode matrix (D) that is obtained from the panning function (W) and the pseudo-inverse mode matrix (Ξ+).

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.

The present document describes a method (400) for rendering an Ambisonics signal using a loudspeaker arrangement including S loudspeakers. The method (400) includes converting (401) a set of N Ambisonics channel signals (111) into a set of unfiltered pre-rendered signals (211), where N>1 and S>1. The method (400) further includes performing near-field compensation (referred to as NFC) filtering (402) 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.

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.

A device 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 an audio scene. The one or more processors are also configured to render, using an object renderer, the first audio data 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, using a first ambisonics renderer, the second audio data to generate a second audio signal. The second audio data represents a second audio source associated with a second priority.

Improved methods and / or apparatus for decoding an encoded audio signal in soundfield format for L loudspeakers. The method and / or apparatus can render an Ambisonics format audio signal to 2D loudspeaker setup(s) based on a rendering matrix. The rendering matrix has elements based on loudspeaker positions and wherein the rendering matrix is determined based on weighting at least an element of a first matrix with a weighting factorℊ=1L.The first matrix is determined based on positions of the L loudspeakers and at least a virtual position of at least a virtual loudspeaker that is added to the positions of the L loudspeakers.

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.