Now I know the answer to it. This extra windowing is called 'Lag windowing'. Its purpose is to smooth the short-term spectral envolope when the pitch is shorter than one frame. Yidan Zhou --- In , "Yidan Zhou" <yidanzhou@y...> wrote: > Hi all, > Now I am reading the standard documents and reference source code > of G.723.1. There is an extra windowing multiplication in between the > Levinson-Durbin recursion and autocorrelation coefficient > calculation. But I do not know why this extra step is necessary. > Could anybody give me clue? > Thanks in advance! > > Best regards, > > Yidan Zhou |