PSYCHOACOUSTIC FILTER DESIGN FOR RATIONAL RESAMPLERS

摘要

The present document relates to the design of anti-aliasing and/or anti-imaging filters for resamplers using rational resampling factors. In particular, the present document relates to a method for designing such filters having a reduced number of filter coefficients or an increased perceptual performance, as well as to the filters designed using such method. A method for designing a filter (102) configured to reduce imaging and/or aliasing of an output audio signal (113) at an output sampling rate (fs_out) is described. The output audio signal (113) is a resampled version of an input audio signal (110) at an input sampling rate (fs_in). The ratio of the output sampling rate (fs_out) and the input sampling rate (fs_in) is a rational number N/M. The filter (102) operates at an upsampled sampling rate which equals N times the input sampling rate (fs_in). The method comprises the steps of selecting an allowed deviation of the frequency response (531, 532) of the filter (102) within a stop band of the filter (102) based on a perceptual frequency response indicative of an auditory spectral sensitivity; wherein the allowed deviation indicates a deviation of the frequency response (531, 532) of the filter (102) from a predetermined attenuation within the stop band; and of determining coefficients of the filter (102) such that the frequency response (531, 532) of the filter (102) is fitted to the allowed deviation of the frequency response (531, 532).