Fraunhofer-gesellschaft Zur Foerderung Der Angewandten Forschung E.v.

Patrick Warmbold

Markus Multrus

Guillaume Fuchs

Nikolaus Rettelbach

Vignesh Subbaraman

Oliver Weiss

Marc Gayer

Christian Griebel

Jérémie Lecomte

Sascha Disch

Frederik Nagel

Stefan Bayer

Christian Ertel

Matthias Hildenbrand

Arthur Tritthart

Oliver Weiß

Jérèmie Lecomte

An audio decoder for providing a decoded audio information includes a arithmetic decoder for providing a plurality of decoded spectral values on the basis of an arithmetically-encoded representation of the spectral values and a frequency-domain-to-time-domain converter for providing a time-domain audio representation using the decoded spectral values. The arithmetic decoder is configured to select a mapping rule describing a mapping of a code value onto a symbol code in dependence on a context state. The arithmetic decoder is configured to determine or modify the current context state in dependence on a plurality of previously-decoded spectral values. The arithmetic decoder is configured to detect a group of a plurality of previously-decoded spectral values, which fulfill, individually or taken together, a predetermined condition regarding their magnitudes, and to determine the current context state in dependence on a result of the detection. An audio encoder uses similar principles.

Audio encoder, audio decoder, method for encoding an audio information, method for decoding an audio information and computer program using a detection of a group of previously-decoded spectral values

An audio decoder includes an arithmetic decoder for providing decoded spectral values on the basis of an arithmetically-encoded representation of the spectral values and a frequency-domain-to-time-domain converter for providing a time-domain audio representation using the decoded spectral values. The arithmetic decoder selects a mapping rule describing a mapping of a code value onto a symbol code in dependence on a context state described by a numeric current context value, and determines the numeric current context value in dependence on a plurality of previously-decoded spectral values. The arithmetic decoder modifies a number representation of a numeric previous context value, describing a context state associated with one or more previously decoded spectral values, in dependence on a context subregion value, to acquire a number representation of a numeric current context value describing a context state associated with one or more spectral values to be decoded. An audio encoder uses a similar concept.

Audio encoder, audio decoder, method for encoding and audio information, method for decoding an audio information and computer program using a modification of a number representation of a numeric previous context value

A codec supporting switching between time-domain aliasing cancellation transform coding mode and time-domain coding mode is made less liable to frame loss by adding a further syntax portion to the frames, depending on which the parser of the decoder may select between a first action of expecting the current frame to have, and thus reading forward aliasing cancellation data from the current frame and a second action of not-expecting the current frame to have, and thus not reading forward aliasing cancellation data from the current frame. In other words, while a bit of coding efficiency is lost due to the provision of the new syntax portion, it is merely the new syntax portion which provides for the ability to use the codec in case of a communication channel with frame loss. Without the new syntax portion, the decoder would not be capable of decoding any data stream portion after a loss and will crash in trying to resume parsing. Thus, in an error prone environment, the coding efficiency is prevented from vanishing by the introduction of the new syntax portion.

Audio encoding/decoding with syntax portions using forward aliasing cancellation

An audio decoder includes an arithmetic decoder for providing decoded spectral values on the basis of an arithmetically encoded representation thereof, and a frequency-domain-to-time-domain converter for providing a time-domain audio representation. The arithmetic decoder selects a mapping rule describing a mapping of a code value onto a symbol code representing a spectral value, or a most significant bit-plane thereof, in a decoded form, in dependence on a context state described by a numeric current context value. The arithmetic decoder determines the numeric current context value in dependence on a plurality of previously decoded spectral values. It evaluates a hash table, entries of which define both significant state values amongst the numeric context values and boundaries of intervals of numeric context values, in order to select the mapping rule, wherein the hash table ari_hash_m is defined as given in FIGS.(),(),() and().

Audio encoder, audio decoder, method for encoding and audio information, method for decoding an audio information and computer program using an optimized hash table

An audio decoder has an arithmetic decoder for providing decoded spectral values on the basis of an arithmetically-encoded representation and a frequency-domain-to-time-domain converter for providing a time-domain audio representation. The arithmetic decoder selects a mapping rule describing a mapping of a code value onto a symbol code in dependence on a context state described by a numeric current context value which is determined in dependence on previously decoded spectral values. The arithmetic decoder obtains a plurality of context subregion values on the basis of previously decoded spectral values and derives a numeric current context value associated with one or more spectral values to be decoded in dependence on stored context subregion values. The arithmetic decoder computes the norm of a vector formed by a plurality of previously decoded spectral values in order to obtain a common context subregion value. An audio encoder uses a similar concept.

Audio encoder, audio decoder, method for encoding and decoding an audio information, and computer program obtaining a context sub-region value on the basis of a norm of previously decoded spectral values

An audio decoder has an arithmetic decoder for providing decoded spectral values on the basis of an arithmetically-encoded representation and a frequency-domain-to-time-domain converter for providing a time-domain audio representation. The arithmetic decoder selects a mapping rule describing a mapping of a code value onto a symbol code in dependence on a numeric current context value describing a current context state. The arithmetic decoder determines the numeric current context value in dependence on a plurality of previously decoded spectral values. The arithmetic decoder evaluates at least one table using an iterative interval size reduction to determine whether the numeric current context value is identical to a table context value described by an entry of the table or lies within an interval described by entries of the table, and derives a mapping rule index value describing a selected mapping table. An audio encoder also uses an iterative interval table size reduction.

Audio encoder, audio decoder, method for encoding an audio information, method for decoding an audio information and computer program using an iterative interval size reduction

An audio decoder includes an arithmetic decoder for providing a plurality of decoded spectral values on the basis of an arithmetically encoded representation of the spectral values, and a frequency-domain-to-time-domain converter for providing a time-domain audio representation using the decoded spectral values. The arithmetic decoder selects a mapping rule describing a mapping of a code value onto a symbol code in dependence on a context state described by a numeric current context value. The arithmetic decoder determines the numeric current context value in dependence on a plurality of previously decoded spectral values. The arithmetic decoder evaluates a hash table, entries of which define both significant state values and boundaries of intervals of numeric context values, in order to select the mapping rule. A mapping rule index value is individually associated to a numeric context value being a significant state value.

Audio encoder, audio decoder, method for encoding and audio information, method for decoding an audio information and computer program using a hash table describing both significant state values and interval boundaries

An audio decoder for providing a decoded audio information includes an arithmetic decoder for providing a plurality of decoded spectral values on the basis of an arithmetically-encoded representation of the spectral values and a frequency-domain-to-time-domain converter for providing a time-domain audio representation using decoded spectral values. The arithmetic decoder is configured to select a mapping rule describing a mapping of a code value onto a symbol code in dependence on a context state. The arithmetic decoder is configured to determine a numeric current context value describing the current context state in dependence on a plurality of previously decoded spectral values and also in dependence on whether a spectral value to be decoded is in a first predetermined frequency region or in a second predetermined frequency region. An audio encoder provides an encoded audio information on the basis of an input audio information.

Audio encoder, audio decoder, method for encoding an audio information, method for decoding an audio information and computer program using a region-dependent arithmetic coding mapping rule

A bandwidth extension encoder for encoding an audio signal has a signal analyzer, a core encoder, a parameter calculator, and a window controller. The audio signal has a low frequency signal having a core frequency band and a high frequency signal having an upper frequency band. The signal analyzer is configured for analyzing the audio signal, the audio signal having a block of audio samples, the block having a specified length in time. The signal analyzer is furthermore configured for determining from a plurality of analysis windows an analysis window to be used for performing a bandwidth extension in a bandwidth extension decoder. The core encoder is configured for encoding the low frequency signal to acquire an encoded or frequency signal. The parameter calculator is configured for calculating bandwidth extension parameters from the high frequency signal. The window controller is configured to provide control information indicating analysis window functions.

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Patrick Warmbold