Mercurial > hg > audiostuff
comparison spandsp-0.0.3/spandsp-0.0.3/src/spandsp/silence_gen.h @ 5:f762bf195c4b
import spandsp-0.0.3
| author | Peter Meerwald <pmeerw@cosy.sbg.ac.at> |
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| date | Fri, 25 Jun 2010 16:00:21 +0200 |
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| 4:26cd8f1ef0b1 | 5:f762bf195c4b |
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| 1 /* | |
| 2 * SpanDSP - a series of DSP components for telephony | |
| 3 * | |
| 4 * silence_gen.c - A silence generator, for inserting timed silences. | |
| 5 * | |
| 6 * Written by Steve Underwood <steveu@coppice.org> | |
| 7 * | |
| 8 * Copyright (C) 2006 Steve Underwood | |
| 9 * | |
| 10 * All rights reserved. | |
| 11 * | |
| 12 * This program is free software; you can redistribute it and/or modify | |
| 13 * it under the terms of the GNU General Public License version 2, as | |
| 14 * published by the Free Software Foundation. | |
| 15 * | |
| 16 * This program is distributed in the hope that it will be useful, | |
| 17 * but WITHOUT ANY WARRANTY; without even the implied warranty of | |
| 18 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the | |
| 19 * GNU General Public License for more details. | |
| 20 * | |
| 21 * You should have received a copy of the GNU General Public License | |
| 22 * along with this program; if not, write to the Free Software | |
| 23 * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA. | |
| 24 * | |
| 25 * $Id: silence_gen.h,v 1.4 2006/10/24 13:45:28 steveu Exp $ | |
| 26 */ | |
| 27 | |
| 28 #if !defined(_SILENCE_GEN_H_) | |
| 29 #define _SILENCE_GEN_H_ | |
| 30 | |
| 31 typedef struct | |
| 32 { | |
| 33 int remaining_samples; | |
| 34 int total_samples; | |
| 35 } silence_gen_state_t; | |
| 36 | |
| 37 #ifdef __cplusplus | |
| 38 extern "C" { | |
| 39 #endif | |
| 40 | |
| 41 /*! Generate a block of silent audio samples. | |
| 42 \brief Generate a block of silent audio samples. | |
| 43 \param s The silence generator context. | |
| 44 \param amp The audio sample buffer. | |
| 45 \param max_len The number of samples to be generated. | |
| 46 \return The number of samples actually generated. This will be zero when | |
| 47 there is nothing to send. | |
| 48 */ | |
| 49 int silence_gen(silence_gen_state_t *s, int16_t *amp, int max_len); | |
| 50 | |
| 51 /*! Set a silence generator context to output continuous silence. | |
| 52 \brief Set a silence generator context to output continuous silence. | |
| 53 \param s The silence generator context. | |
| 54 */ | |
| 55 void silence_gen_always(silence_gen_state_t *s); | |
| 56 | |
| 57 /*! Set a silence generator context to output a specified period of silence. | |
| 58 \brief Set a silence generator context to output a specified period of silence. | |
| 59 \param s The silence generator context. | |
| 60 \param silent_samples The number of samples to be generated. | |
| 61 */ | |
| 62 void silence_gen_set(silence_gen_state_t *s, int silent_samples); | |
| 63 | |
| 64 /*! Alter the period of a silence generator context by a specified amount. | |
| 65 \brief Alter the period of a silence generator context by a specified amount. | |
| 66 \param s The silence generator context. | |
| 67 \param silent_samples The number of samples to change the setting by. A positive number | |
| 68 increases the duration. A negative number reduces it. The duration | |
| 69 is prevented from going negative. | |
| 70 */ | |
| 71 void silence_gen_alter(silence_gen_state_t *s, int silent_samples); | |
| 72 | |
| 73 /*! Find how long a silence generator context has to run. | |
| 74 \brief Find how long a silence generator context has to run. | |
| 75 \param s The silence generator context. | |
| 76 \return The number of samples remaining. | |
| 77 */ | |
| 78 int silence_gen_remainder(silence_gen_state_t *s); | |
| 79 | |
| 80 /*! Find the total silence generated to date by a silence generator context. | |
| 81 \brief Find the total silence generated to date. | |
| 82 \param s The silence generator context. | |
| 83 \return The number of samples generated. | |
| 84 */ | |
| 85 int silence_gen_generated(silence_gen_state_t *s); | |
| 86 | |
| 87 /*! Initialise a timed silence generator context. | |
| 88 \brief Initialise a timed silence generator context. | |
| 89 \param s The silence generator context. | |
| 90 \param the initial number of samples to set the silence to. | |
| 91 \return A pointer to the silence generator context. | |
| 92 */ | |
| 93 silence_gen_state_t *silence_gen_init(silence_gen_state_t *s, int silent_samples); | |
| 94 | |
| 95 #ifdef __cplusplus | |
| 96 } | |
| 97 #endif | |
| 98 | |
| 99 #endif | |
| 100 /*- End of file ------------------------------------------------------------*/ |