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annotate scripts/audio/lin2mu.m @ 20830:b65888ec820e draft default tip gccjit

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dmalcom gcc jit import
author Stefan Mahr <dac922@gmx.de>
date Fri, 27 Feb 2015 16:59:36 +0100
parents 7503499a252b
children
Ignore whitespace changes - Everywhere: Within whitespace: At end of lines:
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1 ## Copyright (C) 1995-2015 John W. Eaton
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2 ##
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3 ## This file is part of Octave.
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4 ##
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5 ## Octave is free software; you can redistribute it and/or modify it
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6 ## under the terms of the GNU General Public License as published by
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7 ## the Free Software Foundation; either version 3 of the License, or (at
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8 ## your option) any later version.
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9 ##
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10 ## Octave is distributed in the hope that it will be useful, but
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11 ## WITHOUT ANY WARRANTY; without even the implied warranty of
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12 ## MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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13 ## General Public License for more details.
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14 ##
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15 ## You should have received a copy of the GNU General Public License
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16 ## along with Octave; see the file COPYING. If not, see
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17 ## <http://www.gnu.org/licenses/>.
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18
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19 ## -*- texinfo -*-
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20 ## @deftypefn {Function File} {} lin2mu (@var{x}, @var{n})
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21 ## Convert audio data from linear to mu-law.
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22 ##
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23 ## Mu-law values use 8-bit unsigned integers. Linear values use @var{n}-bit
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24 ## signed integers or floating point values in the range -1 @leq{} @var{x}
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25 ## @leq{} 1 if @var{n} is 0.
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26 ##
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27 ## If @var{n} is not specified it defaults to 0, 8, or 16 depending on
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28 ## the range of values in @var{x}.
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29 ## @seealso{mu2lin}
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30 ## @end deftypefn
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33 ## Author: Andreas Weingessel <Andreas.Weingessel@ci.tuwien.ac.at>
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34 ## Created: 17 October 1994
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35 ## Adapted-By: jwe
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36
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37 function y = lin2mu (x, n)
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38
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39 if (nargin == 1)
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40 range = max (abs (x (:)));
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41 if (range <= 1)
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42 n = 0;
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43 elseif (range <= 128)
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44 n = 8;
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45 warning ("lin2mu: no precision specified, so using %d", n);
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46 else
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47 n = 16;
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48 endif
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49 elseif (nargin == 2)
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50 if (n != 0 && n != 8 && n != 16)
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51 error ("lin2mu: N must be either 0, 8 or 16");
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52 endif
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53 else
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54 print_usage ();
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55 endif
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56
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57 ## Transform real and n-bit format to 16-bit.
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58 if (n == 0)
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59 ## [-1,1] -> [-32768, 32768]
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60 x = 32768 * x;
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61 elseif (n != 16)
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62 x = 2^(16-n) .* x;
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63 endif
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64
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65 ## Determine sign of x, set sign(0) = 1.
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66 sig = sign (x) + (x == 0);
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68 ## Take absolute value of x, but force it to be smaller than 32636;
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69 ## add bias.
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70 x = min (abs (x), 32635) + 132;
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71
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72 ## Find exponent and fraction of bineary representation.
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73 [f, e] = log2 (x);
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75 y = 64 * sig - 16 * e - fix (32 * f) + 335;
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76
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77 endfunction
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