DIGITAL SIGNAL CODING APPARATUS, DIGITAL SIGNAL DECODING APPARATUS, DIGITAL SIGNAL ARITHMETIC CODING METHOD AND DIGITAL SIGNAL ARITHMETIC DECODING METHOD

A digital signal coding apparatus and method makes a compression coding of a digital signal. The coding apparatus and method codes the digital signal by determining a context model to be used for each type of coding data among a plurality of context models. When the digital signal is divided for each predetermined unit to be coded, the coding apparatus and method multiplexes into a bit stream the information representing an initial state of probability of occurrence of the context of model corresponding to the type of the coding data with a bit stream as part of the coded data of the predetermined unit. The present invention also decodes the compressed digital signal.