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.