A new class of optimal biorthogonal subband coder

In this letter, we introduce a novel two-channel biorthogonal subband coder. The new coder employs the ladder structure (or so-called wavelet with lifting scheme). The coding gain of the biorthogonal coder is always greater than or equal to unity, and it can be expressed in closed form. Moreover the proposed coder has a very low complexity and the perfect reconstruction property is structurally preserved. Given any filter order, the optimal solution can be found by the well-known Levinson fast algorithm. For both AR(1) process and MA(1) process, the proposed biorthogonal coder with 2 taps has a higher coding than the optimal orthonormal coder with infinite number of taps.