gusucode.com > 《MATLAB图像与视频处理实用案例详解》代码 > 《MATLAB图像与视频处理实用案例详解》代码/第 19 章 基于语音识别的信号灯图像模拟控制技术/voicebox/lpcifilt.m
function u=lpcifilt(s,ar,t,dc,fade) %LPCIFILT Apply inverse filter to speech signal U=(S,AR,T,DC,FADE) % % Inputs: S speech signal % AR(nf,p+1) array of ar coefficients; one row per frame % T column vector giving the index of the first sample in each frame % DC(nf) optional dc component will be subtracted from the signal % FADE AR coefficients will be linearly interpolated for FADE samples % either side of frame boundaries % % Example: estimate the 2nd derivative of glotttal flow from a speech signal sp with sample freq fs % % spp=filter([1 -exp(-2*pi*50/fs)],1,sp); % preemphasis zero is at 50 Hz % [lpar,lpe,lpk]=lpcauto(spp,lpcord,floor([0.01 0.02]*fs)); % 20ms frame with 10ms frame increment % overlap=k(1,2)-k(2,1)+1; % overlap between adjacent frames % u=lpcifilt(sp,ar,k(:,1)+floor(overlap/2),0,overlap/4); % do inverse filtering % Copyright (C) Mike Brookes 1997 % Version: $Id: lpcifilt.m,v 1.5 2007/07/18 17:41:49 dmb Exp $ % % VOICEBOX is a MATLAB toolbox for speech processing. % Home page: 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 % http://www.gnu.org/copyleft/gpl.html or by writing to % Free Software Foundation, Inc.,675 Mass Ave, Cambridge, MA 02139, USA. %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% [nf,p1]=size(ar); if nargin<4 | isempty(dc) dc=zeros(nf,1); elseif length(dc)==1 dc=dc(ones(nf,1)); end if nf==1 u=filter(ar,1,s-dc); else p=p1-1; ns=length(s); if nargin<5 | isempty(fade) fade=0; if nargin<3 | isempty(t) t=p1+(0:nf-1)*(ns-p)/nf; end end u=zeros(ns,1); if fade<1 x0=(max(1,ceil(t(nf)-p)):ns)'; u(x0)=filter(ar(nf,:),1,s(x0)-dc(nf)); for i=nf-1:-1:2 x0=(max(1,ceil(t(i)-p)):ceil(t(i+1)-1))'; u(x0)=filter(ar(i,:),1,s(x0)-dc(i)); end x0=(1:ceil(t(2)-1))'; u(x0)=filter(ar(1,:),1,s(x0)-dc(1)); else tb=min(t(nf)+fade,(t(nf)+ns)/2); ta=max(t(nf)-fade,(t(nf-1)+t(nf))/2); t0=max(1,ceil(ta)-p); x0=(t0:ns)'; xb=x0-tb; u(x0)=filter(ar(nf,:),1,s(x0)-dc(nf)).*max((1+(xb-abs(xb))/(2*(tb-ta))),0); for i=nf-1:-1:2 td=tb; tc=ta; tb=min(t(i)+fade,ta); ta=max(t(i)-fade,(t(i-1)+t(i))/2); t1=floor(td); t0=max(1,ceil(ta)-p); x0=(t0:t1)'; xb=x0-tb; xc=x0-tc; u(x0)=u(x0)+filter(ar(i,:),1,s(x0)-dc(i)).*max((1+(xb-abs(xb))/(2*(tb-ta))-(xc+abs(xc))/(2*(td-tc))),0); end t1=floor(tb); x0=(1:t1)'; xc=x0-ta; u(x0)=u(x0)+filter(ar(1,:),1,s(x0)-dc(1)).*(1-(xc+abs(xc))/(2*(tb-ta))); end end