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

摘要

An audio decoder (2200) for providing a decoded audio information (2212) on the basis of an encoded audio information (2210) comprises an arithmetic decoder (2220) for providing a plurality of decoded spectral values (2224) on the basis of an arithmetically-encoded representation (2222) of the spectral values and a frequency-domain-to-time-domain converter (2230) for providing a time-domain audio representation using decoded spectral values (2224), in order to obtain the decoded audio information. 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.