Efficient Codebook Constructions of AIVF Codes

The almost instantaneous variable-to-fixed (AIVF) code is a class of non-prefix codes that parses data sequences into some fixed-length codewords. Recently, the dictionary construction of optimal AIVF code is proposed via a dynamic programming algorithm. However, the algorithm has time complexity $O(AM^{2})$ in both single- and multiple-tree modes, where $A$ denotes the alphabet size, and $M$ denotes the dictionary size. In this paper, we present a greedy-like algorithm to construct the codebook. In particular, the proposed algorithm has time complexity $O(M)$ in single-tree mode and $O(AM)$ in multiple-tree mode.