Patent ID: 8018996

Claim:
An arithmetic decoding apparatus which decodes coded data obtained by converting multivalue information of syntax into binary data and performing context-based adaptive binary arithmetic coding on the binary data, said arithmetic decoding apparatus comprising: a binary data decoder configured to decode the coded data to output binary data; an identifier code calculator configured to calculate next identifier codes upon receiving input of an identifier code uniquely corresponding to a syntax element to which the binary data belongs; a context index calculator configured to calculate context indices respectively corresponding to each of the next identifier codes calculated by said identifier code calculator, the context indices being calculated from among context indices which are identification numbers assigned on a per classification basis to the binary data classified by the identifier code and neighboring information; and a probability variable outputter having a probability variable table holding probability variables corresponding to the context indices, and configured to output probability variables respectively corresponding to the context indices calculated by said context index calculator, wherein in a process cycle in which said binary data decoding unit outputs 1-bit binary data: said binary data decoder is configured to execute the decoding by using one of the probability variables outputted by said probability variable outputter; the calculating for the next identifier codes by said identifier code calculator and the calculating for the context indices by said context index calculator are executed within the process cycle; and the outputting of the probability variables respectively corresponding to the context indices is executed within the process cycle, and a process cycle including the calculating for the next identifier codes by said identifier code calculator and the calculating for the context indices by said context index calculator, a process cycle for the outputting of the probability variables by said probability variable outputter, and a process cycle for the decoding by said binary data decoder are executed simultaneously as a three-staged pipeline.