gusucode.com > 语音信号处理工具箱 - Voicebox源码程序 > Voicebox\lpcar2am.m
function [am,em]=lpcar2am(ar,p); %LPCRR2AM Convert ar coefs to ar coef matrix [AM,EM]=(AR,P) %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. %EM(:,1) is always 1. % %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 % % For each j in 1:P we have AM(j:end:-1:j+1,*) = AM(j:end-1,end,*)'*am(j+1:end,j+1:end,*) % % Also em(*,1:end)' = em(*,2:end)'.*(1-am(1:end-1,end,*).^2) % Copyright (C) Mike Brookes 1997 % % Last modified Fri Sep 15 13:27:44 2000 % % 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(ar); if any(ar(:,1)~=1) ar=ar./ar(:,ones(1,p1)); end p0=p1-1; if nargin < 2 p=p0; end am=zeros(nf,p+1,p+1); em=ones(nf,p+1); e=ones(nf,1); rf=ar; if p>=p0 for jj=1:p+1-p0 am(:,jj:jj+p0,jj)=ar; end else for j=p0:-1:p+2 k = rf(:,j+1); d = (1-k.^2).^(-1); e = e.*d; wj=ones(1,j-1); rf(:,2:j) = (rf(:,2:j)-k(:,wj).*rf(:,j:-1:2)).*d(:,wj); end jj=0; end for jj=jj+1:p j = p+2-jj; k = rf(:,j+1); d = (1-k.^2).^(-1); e = e.*d; wj=ones(1,j-1); rf(:,2:j) = (rf(:,2:j)-k(:,wj).*rf(:,j:-1:2)).*d(:,wj); am(:,jj:end,jj)=rf(:,1:j); em(:,jj)=e; end em(:,end)=e./(1-rf(:,2).^2); am(:,end,end)=1; am=permute(am,[3 2 1]);