Mercurial > hg > octave-nkf
comparison scripts/signal/synthesis.m @ 3191:e4f4b2d26ee9
[project @ 1998-10-23 05:43:59 by jwe]
| author | jwe |
|---|---|
| date | Fri, 23 Oct 1998 05:44:01 +0000 |
| parents | |
| children | 041ea33fbbf4 |
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| 3190:70eb3f4136cd | 3191:e4f4b2d26ee9 |
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| 1 ## Copyright (C) 1995, 1996, 1997 Andreas Weingessel | |
| 2 ## | |
| 3 ## This program is free software; you can redistribute it and/or modify | |
| 4 ## it under the terms of the GNU General Public License as published by | |
| 5 ## the Free Software Foundation; either version 2, or (at your option) | |
| 6 ## any later version. | |
| 7 ## | |
| 8 ## This program is distributed in the hope that it will be useful, but | |
| 9 ## WITHOUT ANY WARRANTY; without even the implied warranty of | |
| 10 ## MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU | |
| 11 ## General Public License for more details. | |
| 12 ## | |
| 13 ## You should have received a copy of the GNU General Public License | |
| 14 ## along with this file. If not, write to the Free Software Foundation, | |
| 15 ## 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA. | |
| 16 | |
| 17 ## usage: X = synthesis (Y, c) | |
| 18 ## | |
| 19 ## recovers a signal X from its short-time Fourier transform Y. c = | |
| 20 ## [win_size, increment, window_type]. | |
| 21 ## | |
| 22 ## Y and c can be derived by [Y, c] = stft (X [, ...]). | |
| 23 | |
| 24 ## Author: AW <Andreas.Weingessel@ci.tuwien.ac.at> | |
| 25 ## Description: Recover a signal from its short-term Fourier transform | |
| 26 | |
| 27 function X = synthesis (Y, c) | |
| 28 | |
| 29 if (nargin != 2) | |
| 30 usage ("X = synthesis (Y, c)"); | |
| 31 endif | |
| 32 | |
| 33 [nr nc] = size (c); | |
| 34 if (nr * nc != 3) | |
| 35 error ("synthesis: c must contain exactly 3 elements"); | |
| 36 endif | |
| 37 | |
| 38 ## not necessary, enables better reading | |
| 39 win = c(1); | |
| 40 inc = c(2); | |
| 41 w_type = c(3); | |
| 42 | |
| 43 if (w_type == 1) | |
| 44 H = hanning (win); | |
| 45 elseif (w_type == 2) | |
| 46 H = hamming (win); | |
| 47 elseif (w_type == 3) | |
| 48 H = ones (win, 1); | |
| 49 else | |
| 50 error ("synthesis: window_type must be 1, 2, or 3"); | |
| 51 endif | |
| 52 | |
| 53 Z = real (ifft (Y)); | |
| 54 st = fix ((win-inc) / 2); | |
| 55 Z = Z(st:st+inc-1, :); | |
| 56 H = H(st:st+inc-1); | |
| 57 | |
| 58 nc = columns(Z); | |
| 59 for i = 1:nc | |
| 60 Z(:, i) = Z(:, i) ./ H; | |
| 61 endfor | |
| 62 | |
| 63 X = reshape(Z, inc * nc, 1); | |
| 64 | |
| 65 endfunction |