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.

摘要

An audio decoder (2200) for providing a decoded audio information on the basis of an encoded audio information comprises an arithmetic decoder (2200) for providing a plurality of decoded spectral values (2224) on the basis of an arithmetically-encoded representation (2222) of the spectral coefficients. The audio decoder also comprises a frequency-domain-to-time-domain converter (2230) for providing a time-domain audio representation using the decoded spectral values (2224), in order to obtain the decoded audio information (2212). 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 numeric current context value describing a current context state. The arithmetic decoder is configured to determine the numeric current context value in dependence on a plurality of previously decoded spectral values. The arithmetic decoder is configured to evaluate 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 to derive a mapping rule index value describing a selected mapping table. An audio encoder also uses an iterative interval table size reduction.