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

Patent metadata

Field	Value
Publication number	US-9978380-B2
Application number	US-201314083412-A
Country	US
Kind code	B2
Filing date	Nov 18, 2013
Priority date	Oct 20, 2009
Publication date	May 22, 2018
Grant date	May 22, 2018

Abstract

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.

First claim

The invention claimed is:

1. An audio decoder for providing a decoded audio information on the basis of an encoded audio information, the audio decoder comprising:
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, in order to acquire the decoded audio information;
wherein 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; and
wherein the arithmetic decoder is configured to determine the current context state in dependence on a plurality of previously-decoded spectral values,
wherein 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 or modify the current context state in dependence on a result of the detection;
wherein the arithmetic decoder is configured to evaluate previously-decoded spectral values of a first time-frequency region, to detect a group of a plurality of spectral values which fulfill, individually or taken together, the predetermined condition regarding their magnitudes, and
wherein the arithmetic decoder is configured to acquire a numeric value representing the context state if the predetermined condition is not fulfilled, in dependence on previously-decoded spectral values of a second time-frequency region which is different from the first time-frequency region;
wherein the audio decoder is implemented using a hardware apparatus, or using a computer, or using a combination of a hardware apparatus and a computer.

2. A method for providing a decoded audio information on the basis of an encoded audio information, the method comprising:
providing a plurality of decoded spectral values on the basis of an arithmetically-encoded representation of the spectral values; and
providing a time-domain audio representation using the decoded spectral values, in order to acquire the decoded audio information;
wherein providing the plurality of decoded spectral values comprises selecting a mapping rule describing a mapping of a code value representing a spectral value, or a most-significant bit-plane of a spectral value, in an encoded form onto a symbol code representing a spectral value, or a most-significant bit-plane of a spectral value, in a decoded form, in dependence on a context state; and
wherein the current context state is determined in dependence on a plurality of previously decoded spectral values,
wherein the method comprises evaluating previously-decoded spectral values of a first time-frequency region, to detect a group of a plurality of spectral values which fulfill, individually or taken together, the predetermined condition regarding their magnitudes, and
wherein the method comprises acquiring a numeric value representing the context state if the predetermined condition is not fulfilled, in dependence on previously-decoded spectral values of a second time-frequency region which is different from the first time-frequency region
wherein a group of a plurality of previously-decoded spectral values, which fulfill, individually or taken together, a predetermined condition regarding their magnitudes is detected, and wherein the current context state is determined or modified in dependence on a result of the detection.

3. A non-transitory computer readable medium comprising a computer program for performing the method for providing a decoded audio information on the basis of an encoded audio information according to claim 2 , when the program runs on a computer.

Assignees

• Fraunhofer Ges Forschung

Inventors

• Fuchs Guillaume
• Subbaraman Vignesh
• Rettelbach Nikolaus
• Multrus Markus
• Gayer Marc
• Warmbold Patrick
• Griebel Christian
• Weiss Oliver

Classifications

• G10L19/008 Primary

  Multichannel audio signal coding or decoding using interchannel correlation to reduce redundancy, e.g. joint-stereo, intensity-coding or matrixing · CPC title

• G10L19/0017 Primary

  Lossless audio signal coding; Perfect reconstruction of coded audio signal by transmission of coding error (G10L19/24 takes precedence) · CPC title

• G10L19/0208

  Subband vocoders · CPC title

• G10L19/00 Primary

  Speech or audio signals analysis-synthesis techniques for redundancy reduction, e.g. in vocoders; Coding or decoding of speech or audio signals, using source filter models or psychoacoustic analysis (in musical instruments G10H) · CPC title