Fractional delay filter design for sample rate conversion

With a large number of different standards of sample rates we often need to use sample rate conversion algorithms. If the resampling ratio is not expressed as the ratio of small integer numbers or is not a fixed value, the sample rate conversion algorithm based on fractional delay filters might be used since it allows for arbitrary resampling ratios. The performance of such algorithm depends solely on the method used to design fractional delay filters. In this paper we propose a novel classification of fractional delay filter design methods dividing them into three general categories: optimal fractional filter design, offset window method and polyphase decomposition. The proposed classification is based on differences in properties of the sample rate conversion algorithm based on fractional delay filters.