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.

摘要

An audio decoder (200) for providing a decoded audio information (212) on the basis of an encoded audio information (210) comprises a arithmetic decoder (230) for providing a plurality of decoded spectral values (232) on the basis of an arithmetically-encoded representation (222) of the spectral values and a frequency-domain-to-time-domain converter (260) for providing a time-domain audio representation (262) using the decoded spectral values, in order to obtain the decoded audio information. The arithmetic decoder (230) 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.