update packages

[CreaPhase.git] / octave_packages / m / signal / synthesis.m

diff --git a/octave_packages/m/signal/synthesis.m b/octave_packages/m/signal/synthesis.m
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+## Copyright (C) 1995-2012 Andreas Weingessel
+##
+## This file is part of Octave.
+##
+## Octave 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.
+##
+## Octave 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 Octave; see the file COPYING.  If not, see
+## <http://www.gnu.org/licenses/>.
+
+## -*- texinfo -*-
+## @deftypefn {Function File} {} synthesis (@var{y}, @var{c})
+## Compute a signal from its short-time Fourier transform @var{y} and a
+## 3-element vector @var{c} specifying window size, increment, and
+## window type.
+##
+## The values @var{y} and @var{c} can be derived by
+##
+## @example
+## [@var{y}, @var{c}] = stft (@var{x} , @dots{})
+## @end example
+## @end deftypefn
+
+## 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)
+    print_usage ();
+  endif
+
+  [nr, nc] = size (c);
+  if (nr * nc != 3)
+    error ("synthesis: C must contain exactly 3 elements");
+  endif
+
+  w_size = c(1);
+  inc    = c(2);
+  w_type = c(3);
+
+  if (w_type == 1)
+    w_coeff = hanning (w_size);
+  elseif (w_type == 2)
+    w_coeff = hamming (w_size);
+  elseif (w_type == 3)
+    w_coeff = ones (w_size, 1);
+  else
+    error ("synthesis: window_type must be 1, 2, or 3");
+  endif
+
+  z = real (ifft (y));
+  st = fix ((w_size-inc) / 2);
+  z = z(st:st+inc-1, :);
+  w_coeff = w_coeff(st:st+inc-1);
+
+  nc = columns(z);
+  for i = 1:nc
+    z(:, i) = z(:, i) ./ w_coeff;
+  endfor
+
+  x = reshape(z, inc * nc, 1);
+
+endfunction