Date Added: Oct 2009
In this paper, the authors introduce a novel codebook partition algorithm for Quantization Index Modulation (QIM), which is applied to information hiding in instant low bit-rate speech stream. The QIM method divides the codebook into two parts, each representing '0' and '1' respectively. Instead of randomly partitioning the codebook, the relationship between codewords is considered. The proposed algorithm - Complementary Neighbor Vertices (CNV) guarantees that every codeword is in the opposite part to its nearest neighbor, and the distortion is limited by a bound. The feasibility of CNV is proved with graph theory.