function [g,a,fc,L]=erbfilters(fs,Ls,varargin)
%ERBFILTERS ERB-spaced filters
% Usage: [g,a,fc,L]=erbfilters(fs,Ls);
% [g,a,fc,L]=erbfilters(fs,Ls,...);
%
% Input parameters:
% fs : Sampling rate (in Hz).
% Ls : Signal length.
% Output parameters:
% g : Cell array of filters.
% a : Downsampling rate for each channel.
% fc : Center frequency of each channel.
% L : Next admissible length suitable for the generated filters.
%
% [g,a,fc]=ERBFILTERS(fs,Ls) constructs a set of filters g that are
% equidistantly spaced on the ERB-scale (see FREQTOERB) with bandwidths
% that are proportional to the width of the auditory filters
% AUDFILTBW. The filters are intended to work with signals with a
% sampling rate of fs.
%
% Note that this function just forwards the arguments to AUDFILTERS.
% Please see the help of AUDFILTERS for more details.
%
% Examples:
% ---------
%
% In the first example, we construct a highly redudant uniform
% filterbank and visualize the result:
%
% [f,fs]=greasy; % Get the test signal
% [g,a,fc]=erbfilters(fs,length(f),'uniform','M',100);
% c=filterbank(f,g,a);
% plotfilterbank(c,a,fc,fs,90,'audtick');
%
% In the second example, we construct a non-uniform filterbank with
% fractional sampling that works for this particular signal length, and
% test the reconstruction. The plot displays the response of the
% filterbank to verify that the filters are well-behaved both on a
% normal and an ERB-scale. The second plot shows frequency responses of
% filters used for analysis (top) and synthesis (bottom). :
%
% [f,fs]=greasy; % Get the test signal
% L=length(f);
% [g,a,fc]=erbfilters(fs,L,'fractional');
% c=filterbank(f,{'realdual',g},a);
% r=2*real(ifilterbank(c,g,a));
% norm(f-r)
%
% % Plot the response
% figure(1);
% subplot(2,1,1);
% R=filterbankresponse(g,a,L,fs,'real','plot');
%
% subplot(2,1,2);
% semiaudplot(linspace(0,fs/2,L/2+1),R(1:L/2+1));
% ylabel('Magnitude');
%
% % Plot frequency responses of individual filters
% gd=filterbankrealdual(g,a,L);
% figure(2);
% subplot(2,1,1);
% filterbankfreqz(gd,a,L,fs,'plot','linabs','posfreq');
%
% subplot(2,1,2);
% filterbankfreqz(g,a,L,fs,'plot','linabs','posfreq');
%
%
% See also: audfilters, filterbank, ufilterbank, ifilterbank, ceil23
%
% References:
% T. Necciari, P. Balazs, N. Holighaus, and P. L. Søndergaard. The ERBlet
% transform: An auditory-based time-frequency representation with perfect
% reconstruction. In Proceedings of the 38th International Conference on
% Acoustics, Speech, and Signal Processing (ICASSP 2013), pages 498--502,
% Vancouver, Canada, May 2013. IEEE.
%
%
% Url: http://ltfat.github.io/doc/filterbank/erbfilters.html
% Copyright (C) 2005-2023 Peter L. Soendergaard <peter@sonderport.dk> and others.
% This file is part of LTFAT version 2.6.0
%
% 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/>.
% Authors: Peter L. Søndergaard, Zdenek Prusa, Nicki Holighaus
[g,a,fc,L]=audfilters(fs,Ls,varargin{:},'erb');