AUDIO ENCODER, AUDIO DECODER, METHOD FOR ENCODING AN INPUT AUDIO INFORMATION, METHOD FOR DECODING AN INPUT AUDIO INFORMATION AND COMPUTER PROGRAM USING IMPROVED CODING TABLES

摘要

An audio decoder comprises 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 obtain a decoded audio information. The arithmetic decoder is configured to derive a group index from a variable-length-codeword representing the group index in dependence on a state index. The arithmetic decoder is configured to derive the values of a most-significant bit-plane of a tuple of spectral values using the group index and an element index, and to provide a tuple of decoded spectral values using the values of the most-significant bit-plane of the tuple of spectral values. The arithmetic decoder is configured to select a cumulative-frequencies-table out of a set of 32 cumulative-frequencies-tables in dependence on the state index, and to apply the selected cumulative-frequencies-table to derive the group index from the variable-length codeword representing the group index.