Patent ID: 6363407
Filing Date: 2002-03-26
Classification: G06F,G10L

Abstract:
A decoding device for extracting a variable quantization code x and a variable scaling factor y from an input bit stream containing the quantization code x and the scaling factor y and calculating x{circumflex over ( )}(a/b)*2{circumflex over ( )}(y/c) (where a, b and c are each an integer constant), the device comprising:an isolation section for isolating x and y from the input bit stream; a first bit shift section for, when x&lE;2{circumflex over ( )}N (where N is a predetermined threshold value), shifting x by a number of bits according to N so as to convert x to x1 which is in a fixed point format; a first memory section for storing, for all possible values of q (where q is an integer such that 0&lE;q&lE;2{circumflex over ( )}N), using q as an address, values of H(q) which have been converted to a fixed point format by shifting q{circumflex over ( )}((aâˆ’b)/b) by a number of bits according to M (where M is an integer value of (N*(aâˆ’b))/b); a second memory section for storing, for all possible values of p (where 0&lE;pa division section for calculating y1, where y1=int(y/c); a modulo calculation section for calculating y2=y%c; a multiplication section for outputting a value obtained by multiplying together a value of H(x) which has been read out from the first memory section using x as an address, a value of G(y2) which has been read out from the second memory section using y2 as an address and a value of x1 which has been converted by the first bit shift section; and a second bit shift section for shifting the output value from the multiplication section by a number of bits according to y1 obtained by the division section.