the first predetermined length and store a unique value; a third table having a separate area for each of the areas in the second table, the area in the third table having an address equal to a value stored in the area in the second table and storing a run-level pair, where an address of the area in the second table is a codeword generated when entropy coding the run-level pair stored in the area in the third table; and a first decode controlling unit for when the first codeword is no greater than the first predetermined length, retrieving from the first table a run-level pair stored in an area whose address is the first codeword, and setting the retrieved run-level pair as the first run-level pair, andaddress, to generate a second coefficient; and a reconstructing unit for reconstructing the two original signal sets using a combination of the first address and the first coefficient and a combination of the second address and the second coefficient.
With the above construction, address calculation and inverse quantization for one run-level pair are carried out in parallel with address calculation and inverse quantization for the other run-level pair, which accelerates computations of the overall inverse quantization.
Here, the reconstructing unit may include: a coefficient storing unit for storing address-coefficient pairs; a coefficient writing unit for writing the combination of the first address and the first coefficient and the combination of the second address and the second coefficient into the coefficient storing unit as two address-coefficient pairs; a block storing unit