Direct construction of nonuniform block orthogonal transforms

The block orthogonal transforms (BOTS) are widely used as a basic technology for processing of voice and video signals. Many BOTs are known at present. However, most of them are uniform BOTs in which the signals are divided into equally spaced frequency bands such as DCT. In general, if the frequency range is nonuniformly divided, there is a possibility that the signal can be processed more efficiently than the case of uniform spacing. Among the methods of configuration of the nonuniform BOT (NUBOT) in which the frequency band is divided into nonuniform spacing, the easiest realization is to connect uniformly spaced BOTs (filter banks) in a tree fashion. In such a tree configuration, the characteristics of each fillet cannot be controlled directly. Therefore, an optimum NUBOT in terms of coding efficiency cannot be realized. In this paper, a method is proposed to realize an optimum NUBOT by direct configuration without a tree configuration.