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5
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1 /*
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2 * SpanDSP - a series of DSP components for telephony
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3 *
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4 * silence_gen.c - A silence generator, for inserting timed silences.
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5 *
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6 * Written by Steve Underwood <steveu@coppice.org>
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7 *
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8 * Copyright (C) 2006 Steve Underwood
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9 *
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10 * All rights reserved.
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11 *
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12 * This program is free software; you can redistribute it and/or modify
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13 * it under the terms of the GNU General Public License version 2, as
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14 * published by the Free Software Foundation.
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15 *
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16 * This program is distributed in the hope that it will be useful,
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17 * but WITHOUT ANY WARRANTY; without even the implied warranty of
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18 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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19 * GNU General Public License for more details.
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20 *
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21 * You should have received a copy of the GNU General Public License
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22 * along with this program; if not, write to the Free Software
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23 * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
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24 *
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25 * $Id: silence_gen.c,v 1.6 2006/11/19 14:07:25 steveu Exp $
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26 */
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27
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28 /*! \file */
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29
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30 #ifdef HAVE_CONFIG_H
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31 #include "config.h"
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32 #endif
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33
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34 #include <inttypes.h>
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35 #include <stdlib.h>
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36 #include <stdio.h>
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37 #include <fcntl.h>
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38 #include <string.h>
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39 #if defined(HAVE_TGMATH_H)
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40 #include <tgmath.h>
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41 #endif
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42 #if defined(HAVE_MATH_H)
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43 #include <math.h>
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44 #endif
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45 #include <assert.h>
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46 #include <limits.h>
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47
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48 #include "spandsp/telephony.h"
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49 #include "spandsp/logging.h"
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50 #include "spandsp/silence_gen.h"
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51
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52 int silence_gen(silence_gen_state_t *s, int16_t *amp, int max_len)
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53 {
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54 if (s->remaining_samples != INT_MAX)
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55 {
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56 if (max_len > s->remaining_samples)
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57 max_len = s->remaining_samples;
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58 s->remaining_samples -= max_len;
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59 }
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60 if (INT_MAX - s->total_samples >= max_len)
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61 s->total_samples += max_len;
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62 memset(amp, 0, max_len*sizeof(int16_t));
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63 return max_len;
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64 }
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65 /*- End of function --------------------------------------------------------*/
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66
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67 void silence_gen_always(silence_gen_state_t *s)
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68 {
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69 s->remaining_samples = INT_MAX;
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70 }
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71 /*- End of function --------------------------------------------------------*/
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72
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73 void silence_gen_set(silence_gen_state_t *s, int silent_samples)
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74 {
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75 s->remaining_samples = silent_samples;
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76 s->total_samples = 0;
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77 }
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78 /*- End of function --------------------------------------------------------*/
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79
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80 void silence_gen_alter(silence_gen_state_t *s, int silent_samples)
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81 {
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82 /* Block negative silences */
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83 if (silent_samples < 0)
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84 {
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85 if (-silent_samples > s->remaining_samples)
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86 silent_samples = -s->remaining_samples;
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87 }
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88 s->remaining_samples += silent_samples;
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89 s->total_samples += silent_samples;
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90 }
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91 /*- End of function --------------------------------------------------------*/
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92
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93 int silence_gen_remainder(silence_gen_state_t *s)
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94 {
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95 return s->remaining_samples;
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96 }
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97 /*- End of function --------------------------------------------------------*/
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98
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99 int silence_gen_generated(silence_gen_state_t *s)
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100 {
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101 return s->total_samples;
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102 }
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103 /*- End of function --------------------------------------------------------*/
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104
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105 silence_gen_state_t *silence_gen_init(silence_gen_state_t *s, int silent_samples)
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106 {
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107 memset(s, 0, sizeof(*s));
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108 s->remaining_samples = silent_samples;
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109 return s;
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110 }
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111 /*- End of function --------------------------------------------------------*/
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112 /*- End of file ------------------------------------------------------------*/
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