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## Copyright (C) 1995, 1996, 1997 Andreas Weingessel
##
## 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, 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 file. If not, write to the Free Software Foundation,
## 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
## usage: X = synthesis (Y, c)
##
## recovers a signal X from its short-time Fourier transform Y. c =
## [win_size, increment, window_type].
##
## Y and c can be derived by [Y, c] = stft (X [, ...]).
## Author: AW <Andreas.Weingessel@ci.tuwien.ac.at>
## Description: Recover a signal from its short-term Fourier transform
function X = synthesis (Y, c)
if (nargin != 2)
usage ("X = synthesis (Y, c)");
endif
[nr, nc] = size (c);
if (nr * nc != 3)
error ("synthesis: c must contain exactly 3 elements");
endif
## not necessary, enables better reading
win = c(1);
inc = c(2);
w_type = c(3);
if (w_type == 1)
H = hanning (win);
elseif (w_type == 2)
H = hamming (win);
elseif (w_type == 3)
H = ones (win, 1);
else
error ("synthesis: window_type must be 1, 2, or 3");
endif
Z = real (ifft (Y));
st = fix ((win-inc) / 2);
Z = Z(st:st+inc-1, :);
H = H(st:st+inc-1);
nc = columns(Z);
for i = 1:nc
Z(:, i) = Z(:, i) ./ H;
endfor
X = reshape(Z, inc * nc, 1);
endfunction
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