Design of robust reversible variable-length codes using the property of free distance

In recent years, reversible variable-length codes (RVLC) have been proposed to recover correct information from erroneous bitstreams. The free distance of a binary code indicates the strength of the code to transmission errors. Since the minimum free distance of RVLC is one, we cannot ensure that encoded data are little exposed. We propose a new code design algorithm for robust RVLC by enhancing the free distance. In the proposed algorithm, we exploit properties of the Huffman code and the average length function satisfying the distance condition in order to improve the code performance.