1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
|
## Copyright (C) 1995-2015 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} {@var{x} =} 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
## @seealso{stft}
## @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
if (numel (c) != 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+1:st+inc, :);
w_coeff = w_coeff(st+1:st+inc);
nc = columns (z);
for i = 1:nc
z(:, i) ./= w_coeff;
endfor
x = reshape (z, inc * nc, 1);
endfunction
|
