codeword located in the position specified by the first position information, and calculating a length of the first codeword; and a second extracting unit for (a) in the first case extracting from the first compressed code stream the second codeword located in a position specified by a sum of the first position information and the calculated length, and (b) in the second case extracting from the second compressed code stream the second codeword located in the position specified by the second position information, and wherein the code decoding unit entropy decodes the extracted first and second codewords to generate two decoded words.
With the above construction, in the decoding of the single compressed code stream the two codewords are extracted in sequence, whereas in the decoding of the twocoefficient and a combination of the second address and the second coefficient.
With the above construction, in the decoding of the single compressed code stream, 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 increases computations for the overall inverse quantization. In the decoding of the two compressed code streams, on the other hand, address calculation and inverse quantization for one run-level pair are carried out independently of address calculation and inverse quantization for the other run-level pair.
Here, the reconstructing unit may include: a first coefficient storing unit for storing address-coefficient pairs; a second coefficient storing unit for storing address-coefficient pairs; a coefficient writing unit for (a) in the first case writing