Efficient recursive structures for forward and inverse discrete cosine transform

In this paper, efficient architectures for realizing the recursive discrete cosine transform (DCT) and the recursive inverse DCT (IDCT) are proposed. By respectively folding the inputs of the DCT and the outputs of the IDCT, efficient formulations of the DCT and IDCT are derived to construct the transform kernels. The data throughput per transformation is twice that of the existing methods by spending only half of the computational cycles used by the single folding algorithms. To further improve efficiency, the double folding recursive architectures of the DCT and IDCT are developed. The computational cycles of the DCT are half of the single folding method, and the data throughput of the IDCT is twice that of the single folding method. The regular and modular properties of the proposed recursive architectures are suitable for very large scale integration (VLSI) implementation. With high throughput advantage, the proposed structures could be implemented with less power consumption, which could be applied to low rate video in mobile and portable information appliances.