Dolby Laboratories Licensing Corporation

Thomson Licensing

Fraunhofer-Gesellschaft Zur Foerderung Der Angewandten Forschung E.V.

Dolby International Ab

Oliver Wuebbolt

Sven Kordon

Alexander Krueger

Johannes Boehm

Peter Jax

Juergen Herre

Stefan Doehla

Fabian Kuech

Florin Ghido

Florian Keiler

Wolfgang Jaegers

Guillaume Fuchs

Oliver Thiergart

Markus Multrus

Stefan Bayer

Frederik Nagel

Matthias Neusinger

Achim Kuntz

Christian Ertel

Sascha Dick

Johannes Böhm

Wolfgang Jagers

The invention proposes a method and a device for arithmetic encoding of a current spectral coefficient using preceding spectral coefficients. Said preceding spectral coefficients are already encoded and both, said preceding and current spectral coefficients, are comprised in one or more quantized spectra resulting from quantizing time-frequency-transform of video, audio or speech signal sample values. Said method comprises processing the preceding spectral coefficients, using the processed preceding spectral coefficients for determining a context class being one of at least two different context classes, using the determined context class and a mapping from the at least two different context classes to at least two different probability density functions for determining the probability density function, and arithmetic encoding the current spectral coefficient based on the determined probability density function wherein processing the preceding spectral coefficients comprises non-uniformly quantizing absolutes of the preceding spectral coefficients for use in determining of the context class.

Method and device for arithmetic encoding or arithmetic decoding

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. For coding, portions of the original HOA representation are predicted from the directional signal components. This prediction provides side information which is required for a corresponding decoding. By using some additional specific purpose bits, a known side information coding processing is improved in that the required number of bits for coding that side information is reduced on average.

Method and apparatus for decoding a bitstream including encoded Higher Order Ambisonics representations

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. For a frame k, the sequence of decoded HOA representations are represented at least in part by

Methods and apparatus for decoding a compressed HOA signal

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.

Methods, apparatus and systems for encoding and decoding of multi-channel Ambisonics audio data

A method for compressing a HOA signal being an input HOA representation with input time frames (C(k)) of HOA coefficient sequences comprises spatial HOA encoding of the input time frames and subsequent perceptual encoding and source encoding. Each input time frame is decomposed () into a frame of predominant sound signals (X(k−1)) and a frame of an ambient HOA component ({tilde over (C)}(k−1)). The ambient HOA component ({tilde over (C)}(k−1)) comprises, in a layered mode, first HOA coefficient sequences of the input HOA representation (c(k−1)) in lower positions and second HOA coefficient sequences (c(k−1)) in remaining higher positions. The second HOA coefficient sequences are part of an HOA representation of a residual between the input HOA representation and the HOA representation of the predominant sound signals.

Methods, apparatus and systems for decompressing a Higher Order Ambisonics (HOA) signal

Method and apparatus for decoding a bitstream including encoded higher order ambisonics representations

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. For a frame k, the sequence of decoded HOA representations are represented at least in part by where &#x109;(k&#x2212;1) corresponds to the corresponding ambient HOA components and &#x109;(k&#x2212;1) corresponds to the corresponding predominant sound components.

Methods, apparatus and systems for encoding and decoding of multi-channel ambisonics audio data

A method for compressing a HOA signal being an input HOA representation with input time frames (C(k)) of HOA coefficient sequences comprises spatial HOA encoding of the input time frames and subsequent perceptual encoding and source encoding. Each input time frame is decomposed () into a frame of predominant sound signals (X(k&#x2212;1)) and a frame of an ambient HOA component ({tilde over (C)}(k&#x2212;1)). The ambient HOA component ({tilde over (C)}(k&#x2212;1)) comprises, in a layered mode, first HOA coefficient sequences of the input HOA representation (c(k&#x2212;1)) in lower positions and second HOA coefficient sequences (c(k&#x2212;1)) in remaining higher positions. The second HOA coefficient sequences are part of an HOA representation of a residual between the input HOA representation and the HOA representation of the predominant sound signals.

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. For a frame k, the sequence of decoded HOA representations are represented at least in part by 

Methods, apparatus and systems for decompressing a higher order ambisonics (HOA) signal

The invention proposes a method and a device for arithmetic encoding of a current spectral coefficient using preceding spectral coefficients. The preceding spectral coefficients are already encoded, and both the preceding and current spectral coefficients are comprised in one or more quantized spectra resulting from quantizing a time-frequency-transform of video, audio or speech signal sample values.

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Hannover, Germany

Oliver Wuebbolt