Patent ID: 7528749
Filing Date: 2009-05-05
Classification: H03M

Abstract:
1. A decoding apparatus for arithmetically decoding input coded data into symbol data by using a state variable and a context variable, comprising: a first decoding unit which executes arithmetic decoding processing by using the state variable and the context variable and outputs first symbol data, and outputs the state variable and the context variable, which are updated by the arithmetic decoding processing, as a first state variable and a first context variable; a second decoding unit which executes arithmetic decoding processing by using the first state variable and the first context variable and outputs second symbol data, and outputs the first state variable and the first context variable, which are updated by the arithmetic decoding processing, as a second state variable and a second context variable; a determination unit which determines on the basis of a value of the first state variable whether to employ the second symbol data as a decoding result; a memory unit which stores the state variable and the context variable and provides the state variable and the context variable to said first decoding unit; a first re-normalization unit which executes re-normalization processing by using the coded data and the first state variable and outputs a first updated state variable; a second re-normalization unit which executes re-normalization processing by using the coded data and the second state variable and outputs a second updated state variable; a first selection unit which selects, from the first context variable and the second context variable, a context variable to be stored in said memory unit; and a second selection unit which selects, from the first updated state variable and the second undated state variable, a state variable to be stored in said memory unit, wherein said first selection unit and said second selection unit execute selection on the basis of a determination result of said determination unit.