Patent ID: 7450774

Claim:
An apparatus for changing a bit rate, in which an input bit stream generated by an image compression encoding method is changed into an output bit stream having a desired bit rate, the apparatus comprising: a changing codeword determiner to select a candidate codeword for each codeword in the input bit stream, each codeword having a run length and a level for transform coefficients; and a codeword changer to selectively change each codeword of the input bit stream into the candidate codeword selected by the changing codeword determiner based on a determination that a number of bits can be reduced by using the candidate codeword in the output bit stream, wherein the changing codeword determiner selects as the candidate codeword shortest one of the candidate codewords satisfying two requirements: (1) having a same run length that of the codeword in the input stream, and (2) having a level less than that of the codeword in the input stream by a preset value, wherein the changing codeword determiner and the codeword changer repeat codeword selection and codeword changing for the output bit stream, after increasing the preset value by 1 for each repetition, until the desired bit rate is satisfied.