DCT ALGORITHMS FOR COMPOSITE SEQUENCE LENGTHS

This paper presents fast algorithms for the type-II and -III discrete cosine transform of composite sequence length, In particular, a radix- q algorithm, where q is an odd integer, is derived for uniform or mixe d radix decomposition of the discrete cosine transform, By combining t he radix-q and radix-2 algorithms, a general decomposition method for any composite length is developed, Reduction of computational complexi ty can be achieved for many sequence lengths compared with that needed by the well-known radix-2 algorithm, Furthermore, both the proposed a nd Chan's mixed radix algorithms achieve the same computational comple xity for N = 3 2(p) and 9 * 2(p). However, our algorithm uses a simp ler decomposition approach and provides a wider range of choices of se quence lengths.