gsm.c

基于sip协议的网络电话源码

/* $Id: gsm.c 1063 2007-03-15 10:11:00Z bennylp $ */
/* 
 * Copyright (C)2003-2007 Benny Prijono <[e-mail]>
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 *
 * 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., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA 
 */
#include <pjmedia-codec/gsm.h>
#include <pjmedia/codec.h>
#include <pjmedia/errno.h>
#include <pjmedia/endpoint.h>
#include <pjmedia/plc.h>
#include <pjmedia/port.h>
#include <pjmedia/silencedet.h>
#include <pj/assert.h>
#include <pj/pool.h>
#include <pj/string.h>
#include <pj/os.h>
#include "gsm/gsm.h"

/*
 * Only build this file if PJMEDIA_HAS_GSM_CODEC != 0
 */
#if defined(PJMEDIA_HAS_GSM_CODEC) && PJMEDIA_HAS_GSM_CODEC != 0


/* Prototypes for GSM factory */
static pj_status_t gsm_test_alloc( pjmedia_codec_factory *factory, 
				   const pjmedia_codec_info *id );
static pj_status_t gsm_default_attr( pjmedia_codec_factory *factory, 
				     const pjmedia_codec_info *id, 
				     pjmedia_codec_param *attr );
static pj_status_t gsm_enum_codecs( pjmedia_codec_factory *factory, 
				    unsigned *count, 
				    pjmedia_codec_info codecs[]);
static pj_status_t gsm_alloc_codec( pjmedia_codec_factory *factory, 
				    const pjmedia_codec_info *id, 
				    pjmedia_codec **p_codec);
static pj_status_t gsm_dealloc_codec( pjmedia_codec_factory *factory, 
				      pjmedia_codec *codec );

/* Prototypes for GSM implementation. */
static pj_status_t  gsm_codec_init( pjmedia_codec *codec, 
				    pj_pool_t *pool );
static pj_status_t  gsm_codec_open( pjmedia_codec *codec, 
				    pjmedia_codec_param *attr );
static pj_status_t  gsm_codec_close( pjmedia_codec *codec );
static pj_status_t  gsm_codec_modify(pjmedia_codec *codec, 
				     const pjmedia_codec_param *attr );
static pj_status_t  gsm_codec_parse( pjmedia_codec *codec,
				     void *pkt,
				     pj_size_t pkt_size,
				     const pj_timestamp *ts,
				     unsigned *frame_cnt,
				     pjmedia_frame frames[]);
static pj_status_t  gsm_codec_encode( pjmedia_codec *codec, 
				      const struct pjmedia_frame *input,
				      unsigned output_buf_len, 
				      struct pjmedia_frame *output);
static pj_status_t  gsm_codec_decode( pjmedia_codec *codec, 
				      const struct pjmedia_frame *input,
				      unsigned output_buf_len, 
				      struct pjmedia_frame *output);
static pj_status_t  gsm_codec_recover(pjmedia_codec *codec,
				      unsigned output_buf_len,
				      struct pjmedia_frame *output);

/* Definition for GSM codec operations. */
static pjmedia_codec_op gsm_op = 
{
    &gsm_codec_init,
    &gsm_codec_open,
    &gsm_codec_close,
    &gsm_codec_modify,
    &gsm_codec_parse,
    &gsm_codec_encode,
    &gsm_codec_decode,
    &gsm_codec_recover
};

/* Definition for GSM codec factory operations. */
static pjmedia_codec_factory_op gsm_factory_op =
{
    &gsm_test_alloc,
    &gsm_default_attr,
    &gsm_enum_codecs,
    &gsm_alloc_codec,
    &gsm_dealloc_codec
};

/* GSM factory */
static struct gsm_codec_factory
{
    pjmedia_codec_factory    base;
    pjmedia_endpt	    *endpt;
    pj_pool_t		    *pool;
    pj_mutex_t		    *mutex;
    pjmedia_codec	     codec_list;
} gsm_codec_factory;


/* GSM codec private data. */
struct gsm_data
{
    void		*encoder;
    void		*decoder;
    pj_bool_t		 plc_enabled;
    pjmedia_plc		*plc;
    pj_bool_t		 vad_enabled;
    pjmedia_silence_det	*vad;
    pj_timestamp	 last_tx;
};



/*
 * Initialize and register GSM codec factory to pjmedia endpoint.
 */
PJ_DEF(pj_status_t) pjmedia_codec_gsm_init( pjmedia_endpt *endpt )
{
    pjmedia_codec_mgr *codec_mgr;
    pj_status_t status;

    if (gsm_codec_factory.pool != NULL)
	return PJ_SUCCESS;

    /* Create GSM codec factory. */
    gsm_codec_factory.base.op = &gsm_factory_op;
    gsm_codec_factory.base.factory_data = NULL;
    gsm_codec_factory.endpt = endpt;

    gsm_codec_factory.pool = pjmedia_endpt_create_pool(endpt, "gsm", 4000, 
						       4000);
    if (!gsm_codec_factory.pool)
	return PJ_ENOMEM;

    pj_list_init(&gsm_codec_factory.codec_list);

    /* Create mutex. */
    status = pj_mutex_create_simple(gsm_codec_factory.pool, "gsm", 
				    &gsm_codec_factory.mutex);
    if (status != PJ_SUCCESS)
	goto on_error;

    /* Get the codec manager. */
    codec_mgr = pjmedia_endpt_get_codec_mgr(endpt);
    if (!codec_mgr) {
	status = PJ_EINVALIDOP;
	goto on_error;
    }

    /* Register codec factory to endpoint. */
    status = pjmedia_codec_mgr_register_factory(codec_mgr, 
						&gsm_codec_factory.base);
    if (status != PJ_SUCCESS)
	goto on_error;

    /* Done. */
    return PJ_SUCCESS;

on_error:
    pj_pool_release(gsm_codec_factory.pool);
    gsm_codec_factory.pool = NULL;
    return status;
}



/*
 * Unregister GSM codec factory from pjmedia endpoint and deinitialize
 * the GSM codec library.
 */
PJ_DEF(pj_status_t) pjmedia_codec_gsm_deinit(void)
{
    pjmedia_codec_mgr *codec_mgr;
    pj_status_t status;

    if (gsm_codec_factory.pool == NULL)
	return PJ_SUCCESS;

    /* We don't want to deinit if there's outstanding codec. */
    /* This is silly, as we'll always have codec in the list if
       we ever allocate a codec! A better behavior maybe is to 
       deallocate all codecs in the list.
    pj_mutex_lock(gsm_codec_factory.mutex);
    if (!pj_list_empty(&gsm_codec_factory.codec_list)) {
	pj_mutex_unlock(gsm_codec_factory.mutex);
	return PJ_EBUSY;
    }
    */

    /* Get the codec manager. */
    codec_mgr = pjmedia_endpt_get_codec_mgr(gsm_codec_factory.endpt);
    if (!codec_mgr) {
	pj_pool_release(gsm_codec_factory.pool);
	gsm_codec_factory.pool = NULL;
	return PJ_EINVALIDOP;
    }

    /* Unregister GSM codec factory. */
    status = pjmedia_codec_mgr_unregister_factory(codec_mgr,
						  &gsm_codec_factory.base);
    
    /* Destroy mutex. */
    pj_mutex_destroy(gsm_codec_factory.mutex);

    /* Destroy pool. */
    pj_pool_release(gsm_codec_factory.pool);
    gsm_codec_factory.pool = NULL;

    return status;
}

/* 
 * Check if factory can allocate the specified codec. 
 */
static pj_status_t gsm_test_alloc( pjmedia_codec_factory *factory, 
				   const pjmedia_codec_info *info )
{
    PJ_UNUSED_ARG(factory);

    /* Check payload type. */
    if (info->pt != PJMEDIA_RTP_PT_GSM)
	return PJMEDIA_CODEC_EUNSUP;

    /* Ignore the rest, since it's static payload type. */

    return PJ_SUCCESS;
}

/*
 * Generate default attribute.
 */
static pj_status_t gsm_default_attr (pjmedia_codec_factory *factory, 
				      const pjmedia_codec_info *id, 
				      pjmedia_codec_param *attr )
{
    PJ_UNUSED_ARG(factory);
    PJ_UNUSED_ARG(id);

    pj_bzero(attr, sizeof(pjmedia_codec_param));
    attr->info.clock_rate = 8000;
    attr->info.channel_cnt = 1;
    attr->info.avg_bps = 13200;
    attr->info.pcm_bits_per_sample = 16;
    attr->info.frm_ptime = 20;
    attr->info.pt = PJMEDIA_RTP_PT_GSM;

    attr->setting.frm_per_pkt = 1;
    attr->setting.vad = 1;
    attr->setting.plc = 1;

    /* Default all other flag bits disabled. */

    return PJ_SUCCESS;
}

/*
 * Enum codecs supported by this factory (i.e. only GSM!).
 */
static pj_status_t gsm_enum_codecs(pjmedia_codec_factory *factory, 
				    unsigned *count, 
				    pjmedia_codec_info codecs[])
{
    PJ_UNUSED_ARG(factory);
    PJ_ASSERT_RETURN(codecs && *count > 0, PJ_EINVAL);

    pj_bzero(&codecs[0], sizeof(pjmedia_codec_info));
    codecs[0].encoding_name = pj_str("GSM");
    codecs[0].pt = PJMEDIA_RTP_PT_GSM;
    codecs[0].type = PJMEDIA_TYPE_AUDIO;
    codecs[0].clock_rate = 8000;
    codecs[0].channel_cnt = 1;

    *count = 1;

    return PJ_SUCCESS;
}

/*
 * Allocate a new GSM codec instance.
 */
static pj_status_t gsm_alloc_codec( pjmedia_codec_factory *factory, 
				    const pjmedia_codec_info *id,
				    pjmedia_codec **p_codec)
{
    pjmedia_codec *codec;
    struct gsm_data *gsm_data;
    pj_status_t status;