www.gusucode.com > 线性时频分析工具箱 - ltfat-1.0.8-win32源码程序 > ltfat/filterbank/filterbankrealtight.m
function gtout=filterbankrealtight(g,a,varargin); %FILTERBANKTIGHT Tight filters of filterbank for real signals only % Usage: gd=filterbanktight(g,a); % % FILTERABANKTIGHT(g,a) computes the canonical tight filters of g for a % channel subsampling rate of a (hop-size). The tight filters work only % for real-valued signals. Use this function on the common construction % where the filters in g only covers the positive frequencies. % % The format of the filters g are described in the % help of FILTERANK. % % To actually invert the output of a filterbank, use the tight filters % together with 2*real(IFILTERBANK(...)) function. % % See also: filterbank, ufilterbank, ifilterbank % Copyright (C) 2005-2012 Peter L. Soendergaard. % This file is part of LTFAT version 1.0.8 % 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 3 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 should have received a copy of the GNU General Public License % along with this program. If not, see <http://www.gnu.org/licenses/>. if nargin<2 error('%s: Too few input parameters.',upper(mfilename)); end; [a,M,longestfilter,lcm_a]=assert_filterbankinput(g,a); definput.keyvals.L=[]; [flags,kv,L]=ltfatarghelper({'L'},definput,varargin); if isempty(L) L=ceil(longestfilter/lcm_a)*lcm_a; end; if all(a==a(1)) % Uniform filterbank, use polyphase representation a=a(1); G=zeros(L,M); for ii=1:M G(:,ii)=fft(fir2long(g{ii},L)); end; N=L/a; gt=zeros(N,M); for w=0:N-1 idx_a = mod(w-(0:a-1)*N,L)+1; idx_b = mod((0:a-1)*N-w,L)+1; Ha = G(idx_a,:); Hb = conj(G(idx_b,:)); Ha=sqrtm(Ha*Ha'+Hb*Hb')\Ha; gt(idx_a,:)=Ha; end; gt=ifft(gt)*sqrt(a); if isreal(g) gt=real(gt); end; gtout=cell(1,M); for m=1:M gtout{m}=gt(:,m); end; else error('Not implemented yet.'); end;