A regressive structure for on-line computation of arbitrary length DCT-IV and DST-IV transforms

We demonstrate that the forward and inverse type-IV discrete cosine transform (DCT-IV/IDCT-IV) and type-IV discrete sine transform (DST-IV/IDST-IV) can be efficiently computed by a regressive structure. In our approach, we suggest using the recursive sinusoidal formulas corresponding to the transform kernels of these transforms to obtain an IIR filter structure. The novel structure is then used for parallel computation of arbitrary length DCT-IV/IDCT-IV and DST-IV/IDST-IV. Since the architecture can be highly parallel, simple, and regular, it is most suitable for VLSI implementation. Moreover, we do not need to permute the input sequence, which makes the approach particularly suitable for on-line computation.