A design of nonuniform cosine modulated filter banks

A design method of nonuniform CMF banks is presented which is derived in association with a uniform CMF bank. In this derived nonuniform CMF bank, each constituent nonuniform filter is formed by merging the relevant uniform filters in the associated uniform CMF bank. The validity of the derived design is investigated in terms of the band selectivity of the nonuniform filters, the alias cancellation among the nonuniform analysis and synthesis filters, and the distortion function of the overall filter bank. The investigations are done in a rigorous manner via three proved properties, which provide the criterion that the proposed design method is applicable if, and only if, the upper band edge frequency of each nonuniform filter is an integral multiple of the bandwidth of the corresponding band. Design and implementation aspects are considered for the proposed nonuniform CMF bank, which reveals that the design procedure and the structure of the uniform CMF bank are mostly preserved in the nonuniform implementation.