AUDIO SIGNAL TIME SCALE MODIFICATION

摘要

A method of time-scale modification processing of frame-based digital audio signals based on Synchronous Overlap Addition in which an original frame of digital audio is copied, the original and copied frames are partly overlapped to give a desired new duration to within a predetermined tolerance, the extent of overlap is adjusted within the predetermined tolerance by reference to a cross correlation determination of the best match between the overlapping portions of the original and copied frame; and a new audio frame is generated from the non-overlapping portions of the original and copied frame and by cross-fading between the overlapping portions. To reduce the computational load, a profiling procedure is applied to the original and copied frame prior to cross correlation, such as to reduce the specification of each audio frame portion ( 100 ) to a finite array of values ( 101-106 ), and the cross correlation is then performed in relation only to the pair of finite arrays of values. To further simplify computation, the values ( 101-106 ) are identified as maxima or minima for the signal and are both stored and processed as the only non-zero values in a matrix representation of the frame. A digital signal processing apparatus embodying this technique is also provided.