www.gusucode.com > 语音信号处理工具箱 - Voicebox源码程序 > Voicebox\lpcrr2am.m
function [am,em]=lpcrr2am(rr); %LPCRR2AM Convert autocorrelation coefs to ar coef matrix [AM,EM]=(RR) %AM is a 3-dimensional matrix of size (p+1,p+1,nf) where p is the lpc order %and nf the number of frames. %The matrix AM(:,:,*) is upper triangular with 1's on the main diagonal %and contains the lpc coefficients for all orders from p down to 0. % %For lpc order p+1-r, AM(r,r:p+1,*), AM(p+1:-1:r,p+1,*) and EM(*,r) contain %the lpc coefficients, reflection coefficients and the residual energy respectively. % %If A=am(:,:,*), R=toeplitz(rr(*,:)) and E=diag(em(*,:)), then % A*R*A'=E; inv(R)=A'*(1/E)*A; A*R is lower triangular with the same diagonal as E % % This routine is equivalent to: c=chol(inv(toeplitz(rr))); d=diag(c).^-1; em=d.^2; am=diag(d)*c % Copyright (C) Mike Brookes 1997 % % Last modified Fri Dec 3 16:16:20 1999 % % VOICEBOX is a MATLAB toolbox for speech processing. Home page is at % http://www.ee.ic.ac.uk/hp/staff/dmb/voicebox/voicebox.html % %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% % This program is free software; you can redistribute it and/or modify % it under the terms of the GNU General Public License as published by % the Free Software Foundation; either version 2 of the License, or % (at your option) any later version. % % This program is distributed in the hope that it will be useful, % but WITHOUT ANY WARRANTY; without even the implied warranty of % MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the % GNU General Public License for more details. % % You can obtain a copy of the GNU General Public License from % ftp://prep.ai.mit.edu/pub/gnu/COPYING-2.0 or by writing to % Free Software Foundation, Inc.,675 Mass Ave, Cambridge, MA 02139, USA. %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% [nf,p1]=size(rr); p=p1-1; p2=p1+1; am=zeros(nf,p1,p1); em=zeros(nf,p1); am(:,p1,p1)=1; em(:,p1)=rr(:,1); ar=ones(nf,p1); ar(:,2) = -rr(:,2)./rr(:,1); e = rr(:,1).*(ar(:,2).^2-1); for n = 2:p q=p2-n; em(:,q)=-e; am(:,q:p1,q)=ar(:,1:n); k = (rr(:,n+1)+sum(rr(:,n:-1:2).*ar(:,2:n),2)) ./ e; ar(:,2:n) = ar(:,2:n)+k(:,ones(1,n-1)).*ar(:,n:-1:2); ar(:,n+1) = k; e = e.*(1-k.^2); end em(:,1)=-e; am(:,:,1)=ar; am=permute(am,[3 2 1]);