Method and device for arithmetic encoding or arithmetic decoding

An apparatus for arithmetic decoding of a current spectral coefficient, the apparatus comprising:

• a processor configured to process preceding spectral coefficients;
• a context classifier configured to determine a context class based on a processed preceding spectral coefficients, wherein the context class-is determined from at least two different context classes, and wherein the context class is based on a sum of quantized absolutes of the preceding spectral coefficients, a receiver for receiving a reset signal, wherein, in response to the reset signal, only preceding spectral coefficients of current frame are used to determine the context class;
• a probability density module configured to determine a probability density function, said probability density module being adapted to use a mapping from the at least two different context classes to at least two different probability density functions to determine the probability density function;
• and
• an arithmetic decoder configured to arithmetically decode the current spectral coefficient based on the probability density function, wherein the decoding is based on a look up table which is determined based on the context class, wherein the mapping is based on a look-up table or a hash table.