Arithmetic encoders, arithmetic decoders, methods for arithmetic encoding, methods for arithmetic decoding, computer programs, encoded representations and data streams for state variable updating and / or for state variable initialization

Abstract

Embodiments comprise an arithmetic encoder for encoding a plurality of symbols having symbol values, wherein the arithmetic encoder is configured to derive an interval size information for an arithmetic encoding of one or more symbol values to be encoded on the basis of one or more state variable values, which represent statistics of a plurality of previously encoded symbol values, wherein the arithmetic encoder is configured to update the one or more state variable values in dependence on an encoded symbol, in order to obtain one or more updated sate variable values for an encoding of a subsequent symbol; wherein the arithmetic encoder is configured to use a first, comparatively faster adaptation rate for an update of one or more of the state variable values for a predetermined number of adaptation steps; and wherein the arithmetic encoder is configured to use a second, comparatively slower adaptation rate for the update of one or more of the state variable values when the predetermined number of adaptation steps is completed. Furthermore, an arithmetic encoder is disclosed which is configured to determine one or more initialization values for the one or more state variable values in dependence on a quantization parameter which determines a quantization step size for a quantization of one or more values to be encoded using the symbols. Furthermore, corresponding decoders, methods, computer programs, encoded representations and data streams are disclosed.