no greater than the third predetermined length and store two run-level pairs, the former codeword being generated when entropy coding the former run-level pair, and the latter codeword being generated when entropy coding the latter run-level pair; and a decode controlling unit for retrieving from the ninth table two run-level pairs stored in an area whose address is a result of concatenating the first and second codewords in the stated order, and setting the retrieved former and latter run-level pairs respectively as the first and second run-level pairs, and wherein the signal reconstructing unit reconstructs the two original signal sets based on the first and second run-level pairs.
With the above construction, the two short codewords extracted from the compressed code stream are entropy decoded in parallel into twoquantizing unit for inverse quantizing the level of the second run-level pair using the calculated second address, 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 for 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