Digital signal coding apparatus, digital signal decoding apparatus; digital signal arithmetic coding method, and digital signal arithmetic decoding method

A digital signal coding method for making a compression coding of a digital signal, comprising:

• arithmetic coding said digital signal by determining a context model to be used for each type of coding data among a plurality of context models;
• dividing said digital signal for each predetermined unit to be coded, and
• multiplexing into a bit stream the information representing an initial state of probability of occurrence of the context of model corresponding to the type of said coding data and information of initializing a register value which shows an arithmetic decoding process with a bit stream as part of the coded data of said predetermined unit.

A digital signal coding apparatus for making a compression coding of a digital signal;

• comprising:
• a coding unit for arithmetic coding said digital signal by determining a context model to be used for each type of coding data among a plurality of context models;
• wherein said coding unit, when said digital signal is divided for each predetermined unit to be coded, 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 said coding data with a bit stream as part of the coded data of said predetermined unit.