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view 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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/* * SpanDSP - a series of DSP components for telephony * * silence_gen.c - A silence generator, for inserting timed silences. * * Written by Steve Underwood <steveu@coppice.org> * * Copyright (C) 2006 Steve Underwood * * All rights reserved. * * This program is free software; you can redistribute it and/or modify * it under the terms of the GNU General Public License version 2, as * published by the Free Software Foundation. * * This program 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 this program; if not, write to the Free Software * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA. * * $Id: silence_gen.h,v 1.4 2006/10/24 13:45:28 steveu Exp $ */ #if !defined(_SILENCE_GEN_H_) #define _SILENCE_GEN_H_ typedef struct { int remaining_samples; int total_samples; } silence_gen_state_t; #ifdef __cplusplus extern "C" { #endif /*! Generate a block of silent audio samples. \brief Generate a block of silent audio samples. \param s The silence generator context. \param amp The audio sample buffer. \param max_len The number of samples to be generated. \return The number of samples actually generated. This will be zero when there is nothing to send. */ int silence_gen(silence_gen_state_t *s, int16_t *amp, int max_len); /*! Set a silence generator context to output continuous silence. \brief Set a silence generator context to output continuous silence. \param s The silence generator context. */ void silence_gen_always(silence_gen_state_t *s); /*! Set a silence generator context to output a specified period of silence. \brief Set a silence generator context to output a specified period of silence. \param s The silence generator context. \param silent_samples The number of samples to be generated. */ void silence_gen_set(silence_gen_state_t *s, int silent_samples); /*! Alter the period of a silence generator context by a specified amount. \brief Alter the period of a silence generator context by a specified amount. \param s The silence generator context. \param silent_samples The number of samples to change the setting by. A positive number increases the duration. A negative number reduces it. The duration is prevented from going negative. */ void silence_gen_alter(silence_gen_state_t *s, int silent_samples); /*! Find how long a silence generator context has to run. \brief Find how long a silence generator context has to run. \param s The silence generator context. \return The number of samples remaining. */ int silence_gen_remainder(silence_gen_state_t *s); /*! Find the total silence generated to date by a silence generator context. \brief Find the total silence generated to date. \param s The silence generator context. \return The number of samples generated. */ int silence_gen_generated(silence_gen_state_t *s); /*! Initialise a timed silence generator context. \brief Initialise a timed silence generator context. \param s The silence generator context. \param the initial number of samples to set the silence to. \return A pointer to the silence generator context. */ silence_gen_state_t *silence_gen_init(silence_gen_state_t *s, int silent_samples); #ifdef __cplusplus } #endif #endif /*- End of file ------------------------------------------------------------*/