V_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 boundaries0001 function u=v_lpcifilt(s,ar,t,dc,fade) 0002 %V_LPCIFILT Apply inverse filter to speech signal U=(S,AR,T,DC,FADE) 0003 % 0004 % Inputs: S speech signal 0005 % AR(nf,p+1) array of ar coefficients; one row per frame 0006 % T column vector giving the index of the first sample in each frame 0007 % DC(nf) optional dc component will be subtracted from the signal 0008 % FADE AR coefficients will be linearly interpolated for FADE samples 0009 % either side of frame boundaries 0010 % 0011 0012 % Example usage: generate an inverse filtered waveform 0013 % 0014 % [sp,fs]=v_readwav('infile.wav'); 0015 % lpcord=2+floor(fs/1000); 0016 % spp=filter([1 -exp(-2*pi*50/fs)],1,sp); % preemphasis zero is at 50 Hz 0017 % [lpar,lpe,lpk]=v_lpcauto(spp,lpcord,floor([0.01 0.02]*fs)); % 20ms frame with 10ms frame increment 0018 % overlap=lpk(1,2)-lpk(2,1)+1; % overlap between adjacent frames 0019 % u=v_lpcifilt(sp,lpar,lpk(:,1)+floor(overlap/2),0,overlap/4); % do inverse filtering 0020 % v_writewav(u,fs,'outfile.wav'); 0021 0022 % Copyright (C) Mike Brookes 1997 0023 % Version: $Id: v_lpcifilt.m 10865 2018-09-21 17:22:45Z dmb $ 0024 % 0025 % VOICEBOX is a MATLAB toolbox for speech processing. 0026 % Home page: http://www.ee.ic.ac.uk/hp/staff/dmb/voicebox/voicebox.html 0027 % 0028 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% 0029 % This program is free software; you can redistribute it and/or modify 0030 % it under the terms of the GNU General Public License as published by 0031 % the Free Software Foundation; either version 2 of the License, or 0032 % (at your option) any later version. 0033 % 0034 % This program is distributed in the hope that it will be useful, 0035 % but WITHOUT ANY WARRANTY; without even the implied warranty of 0036 % MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the 0037 % GNU General Public License for more details. 0038 % 0039 % You can obtain a copy of the GNU General Public License from 0040 % http://www.gnu.org/copyleft/gpl.html or by writing to 0041 % Free Software Foundation, Inc.,675 Mass Ave, Cambridge, MA 02139, USA. 0042 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% 0043 0044 [nf,p1]=size(ar); 0045 if nargin<4 | isempty(dc) 0046 dc=zeros(nf,1); 0047 elseif length(dc)==1 0048 dc=dc(ones(nf,1)); 0049 end 0050 if nf==1 0051 u=filter(ar,1,s-dc); 0052 else 0053 p=p1-1; 0054 ns=length(s); 0055 if nargin<5 | isempty(fade) 0056 fade=0; 0057 if nargin<3 | isempty(t) 0058 t=p1+(0:nf-1)*(ns-p)/nf; 0059 end 0060 end 0061 u=zeros(ns,1); 0062 if fade<1 0063 x0=(max(1,ceil(t(nf)-p)):ns)'; 0064 u(x0)=filter(ar(nf,:),1,s(x0)-dc(nf)); 0065 for i=nf-1:-1:2 0066 x0=(max(1,ceil(t(i)-p)):ceil(t(i+1)-1))'; 0067 u(x0)=filter(ar(i,:),1,s(x0)-dc(i)); 0068 end 0069 x0=(1:ceil(t(2)-1))'; 0070 u(x0)=filter(ar(1,:),1,s(x0)-dc(1)); 0071 0072 else 0073 tb=min(t(nf)+fade,(t(nf)+ns)/2); 0074 ta=max(t(nf)-fade,(t(nf-1)+t(nf))/2); 0075 t0=max(1,ceil(ta)-p); 0076 x0=(t0:ns)'; 0077 xb=x0-tb; 0078 u(x0)=filter(ar(nf,:),1,s(x0)-dc(nf)).*max((1+(xb-abs(xb))/(2*(tb-ta))),0); 0079 for i=nf-1:-1:2 0080 td=tb; 0081 tc=ta; 0082 tb=min(t(i)+fade,ta); 0083 ta=max(t(i)-fade,(t(i-1)+t(i))/2); 0084 t1=floor(td); 0085 t0=max(1,ceil(ta)-p); 0086 x0=(t0:t1)'; 0087 xb=x0-tb; 0088 xc=x0-tc; 0089 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); 0090 end 0091 t1=floor(tb); 0092 x0=(1:t1)'; 0093 xc=x0-ta; 0094 u(x0)=u(x0)+filter(ar(1,:),1,s(x0)-dc(1)).*(1-(xc+abs(xc))/(2*(tb-ta))); 0095 0096 end 0097 end 0098