www.gusucode.com > 线性时频分析工具箱 - ltfat-1.0.1源码程序 > 线性时频分析工具箱 - LTFAT\gabor\wmdct.m

    function [c,Ls,g]=wmdct(f,g,M,L)
%WMDCT  Windowed MDCT transform.
%   Usage:  c=wmdct(f,g,M);
%           c=wmdct(f,g,M,L);
%           [c,Ls]=wmdct(f,g,M);
%           [c,Ls]=wmdct(f,g,M,L);
%
%   Input parameters:
%         f     : Input data
%         g     : Window function.
%         M     : Number of bands.
%         L     : Length of transform to do.
%   Output parameters:
%         c     : 2*M x N array of coefficients.
%         Ls    : Length of input signal.
%
%   WMDCT(f,g,M) computes a Windowed Modified Discrete Cosine Transform with
%   M bands and window g.
%
%   The length of the transform will be the smallest possible that is
%   larger than the signal. f will be zero-extended to the length of the 
%   transform. If f is a matrix, the transformation is applied to each column.
%   g must be whole-point even.
%
%   The window g may be a vector of numerical values, a text string or a
%   cell array. See the help of WILWIN for more details.
%
%   WMDCT(f,g,M,L) computes the MDCT transform as above, but does
%   a transform of length L. f will be cut or zero-extended to length L
%   before the transform is done.
%
%   [c,Ls]=WMDCT(f,g,M) or [c,Ls]=WMDCT(f,g,M,L) additionally return the
%   length of the input signal f. This is handy for reconstruction:
%
%            [c,Ls]=wmdct(f,g,M);
%            fr=iwmdct(c,gd,M,Ls);
%
%   will reconstuct the signal f no matter what the length of f is, provided
%   that gd is a dual Wilson window of g.
%
%   [c,Ls,g]=WMDCT(...) additionally outputs the window used in the
%   transform. This is useful if the window was generated from a description
%   in a string or cell array.
%
%   The WMDCT is sometimes known as an odd-stacked cosine modulated filter
%   bank. The WMDCT defined by this routine is slightly different from the
%   most common definition of the WMDCT, in order to be able to use the
%   same window functions as the Wilson transform.
%
%   Assume that the following code has been executed for a column vector f
%   of length L:
%
%            c=wmdct(f,g,M);  % Compute the WMDCT of f.
%            N=size(c,2);    % Number of translation coefficients.
%
%   The following holds for m=0,...,M-1 
%   and n=0,...,N-1:
%
%   If m+n is even:
%
%                     L-1
%        c(m+1,n+1) = sum f(l+1)*cos(pi*(m+.5)*l/M+pi/4)*g(l-n*M+1)
%                     l=0
%
%   If m+n is odd:
%                     L-1
%        c(m+1,n+1) = sum f(l+1)*sin(pi*(m+.5)*l/M+pi/4)*g(l-n*M+1)
%                     l=0
%
%   See also:  iwmdct, wilwin, dwilt, wildual, wilorth
%
%   References:
%     H. Bölcskei and F. Hlawatsch. Oversampled Wilson-type cosine modulated
%     filter banks with linear phase. In Asilomar Conf. on Signals, Systems,
%     and Computers, pages 998-1002, nov 1996.
%     
%     H. S. Malvar. Signal Processing with Lapped Transforms. Artech House
%     Publishers, 1992.
%     
%     J. P. Princen and A. B. Bradley. Analysis/synthesis filter bank design
%     based on time domain aliasing cancellation. IEEE Transactions on
%     Acoustics, Speech, and Signal Processing, ASSP-34(5):1153-1161, 1986.
%     
%     J. P. Princen, A. W. Johnson, and A. B. Bradley. Subband/transform
%     coding using filter bank designs based on time domain aliasing
%     cancellation. Proceedings - ICASSP, IEEE International Conference on
%     Acoustics, Speech and Signal Processing, pages 2161-2164, 1987.

% Copyright (C) 2005-2011 Peter L. Soendergaard.
% This file is part of LTFAT version 1.0.1
% 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/>.

%   AUTHOR:    Peter Soendergaard
%   TESTING:   TEST_WMDCT
%   REFERENCE: REF_WMDCT

error(nargchk(3,4,nargin));

if nargin<4
  L=[];
end;

[f,g,L,Ls,W,info] = gabpars_from_windowsignal(f,g,M,2*M,L,'WMDCT');

c  = comp_dwiltiii(f,g,M,L);