Sat Aug 6 00:39:54 2011

Asterisk developer's documentation


codec_gsm.c File Reference

Translate between signed linear and Global System for Mobile Communications (GSM). More...

#include "asterisk.h"
#include <fcntl.h>
#include <stdlib.h>
#include <unistd.h>
#include <netinet/in.h>
#include <string.h>
#include <stdio.h>
#include "asterisk/lock.h"
#include "asterisk/translate.h"
#include "asterisk/config.h"
#include "asterisk/options.h"
#include "asterisk/module.h"
#include "asterisk/logger.h"
#include "asterisk/channel.h"
#include "asterisk/utils.h"
#include <gsm/gsm.h>
#include "../formats/msgsm.h"
#include "slin_gsm_ex.h"
#include "gsm_slin_ex.h"

Go to the source code of this file.

Data Structures

struct  gsm_translator_pvt

Defines

#define BUFFER_SAMPLES   8000
#define GSM_FRAME_LEN   33
#define GSM_SAMPLES   160
#define MSGSM_FRAME_LEN   65

Functions

static void __reg_module (void)
static void __unreg_module (void)
static void gsm_destroy_stuff (struct ast_trans_pvt *pvt)
static int gsm_new (struct ast_trans_pvt *pvt)
static int gsmtolin_framein (struct ast_trans_pvt *pvt, struct ast_frame *f)
 decode and store in outbuf.
static struct ast_framegsmtolin_sample (void)
static int lintogsm_framein (struct ast_trans_pvt *pvt, struct ast_frame *f)
 store samples into working buffer for later decode
static struct ast_framelintogsm_frameout (struct ast_trans_pvt *pvt)
 encode and produce a frame
static struct ast_framelintogsm_sample (void)
static int load_module (void)
static int reload (void)
 standard module glue
static int unload_module (void)

Variables

static struct ast_module_info __mod_info = { .name = AST_MODULE, .flags = AST_MODFLAG_DEFAULT | AST_MODFLAG_BUILDSUM, .description = "GSM Coder/Decoder" , .key = "This paragraph is copyright (c) 2006 by Digium, Inc. \In order for your module to load, it must return this \key via a function called \"key\". Any code which \includes this paragraph must be licensed under the GNU \General Public License version 2 or later (at your \option). In addition to Digium's general reservations \of rights, Digium expressly reserves the right to \allow other parties to license this paragraph under \different terms. Any use of Digium, Inc. trademarks or \logos (including \"Asterisk\" or \"Digium\") without \express written permission of Digium, Inc. is prohibited.\n" , .buildopt_sum = "361d7bb937402d51e4658efb5b4d76e4" , .load = load_module, .unload = unload_module, .reload = reload, }
static const struct ast_module_infoast_module_info = &__mod_info
static struct ast_translator gsmtolin
static struct ast_translator lintogsm


Detailed Description

Translate between signed linear and Global System for Mobile Communications (GSM).

Definition in file codec_gsm.c.


Define Documentation

#define BUFFER_SAMPLES   8000

Definition at line 65 of file codec_gsm.c.

#define GSM_FRAME_LEN   33

Definition at line 67 of file codec_gsm.c.

Referenced by gsmtolin_framein(), and lintogsm_frameout().

#define GSM_SAMPLES   160

Definition at line 66 of file codec_gsm.c.

Referenced by gsm_read(), gsm_seek(), gsm_tell(), gsmtolin_framein(), gsmtolin_sample(), lintogsm_frameout(), and wav_read().

#define MSGSM_FRAME_LEN   65

Definition at line 68 of file codec_gsm.c.

Referenced by gsmtolin_framein().


Function Documentation

static void __reg_module ( void   )  [static]

Definition at line 270 of file codec_gsm.c.

static void __unreg_module ( void   )  [static]

Definition at line 270 of file codec_gsm.c.

static void gsm_destroy_stuff ( struct ast_trans_pvt pvt  )  [static]

Definition at line 203 of file codec_gsm.c.

References gsm_translator_pvt::gsm, and ast_trans_pvt::pvt.

00204 {
00205    struct gsm_translator_pvt *tmp = pvt->pvt;
00206    if (tmp->gsm)
00207       gsm_destroy(tmp->gsm);
00208 }

static int gsm_new ( struct ast_trans_pvt pvt  )  [static]

Definition at line 75 of file codec_gsm.c.

References gsm_translator_pvt::gsm, and ast_trans_pvt::pvt.

00076 {
00077    struct gsm_translator_pvt *tmp = pvt->pvt;
00078    
00079    return (tmp->gsm = gsm_create()) ? 0 : -1;
00080 }

static int gsmtolin_framein ( struct ast_trans_pvt pvt,
struct ast_frame f 
) [static]

decode and store in outbuf.

Definition at line 113 of file codec_gsm.c.

References ast_log(), BUFFER_SAMPLES, conv65(), ast_trans_pvt::datalen, f, gsm_translator_pvt::gsm, GSM_FRAME_LEN, GSM_SAMPLES, len(), LOG_WARNING, MSGSM_FRAME_LEN, ast_trans_pvt::outbuf, ast_trans_pvt::pvt, and ast_trans_pvt::samples.

00114 {
00115    struct gsm_translator_pvt *tmp = pvt->pvt;
00116    int x;
00117    int16_t *dst = (int16_t *)pvt->outbuf;
00118    /* guess format from frame len. 65 for MSGSM, 33 for regular GSM */
00119    int flen = (f->datalen % MSGSM_FRAME_LEN == 0) ?
00120       MSGSM_FRAME_LEN : GSM_FRAME_LEN;
00121 
00122    for (x=0; x < f->datalen; x += flen) {
00123       unsigned char data[2 * GSM_FRAME_LEN];
00124       unsigned char *src;
00125       int len;
00126       if (flen == MSGSM_FRAME_LEN) {
00127          len = 2*GSM_SAMPLES;
00128          src = data;
00129          /* Translate MSGSM format to Real GSM format before feeding in */
00130          /* XXX what's the point here! we should just work
00131           * on the full format.
00132           */
00133          conv65(f->data + x, data);
00134       } else {
00135          len = GSM_SAMPLES;
00136          src = f->data + x;
00137       }
00138       /* XXX maybe we don't need to check */
00139       if (pvt->samples + len > BUFFER_SAMPLES) {   
00140          ast_log(LOG_WARNING, "Out of buffer space\n");
00141          return -1;
00142       }
00143       if (gsm_decode(tmp->gsm, src, dst + pvt->samples)) {
00144          ast_log(LOG_WARNING, "Invalid GSM data (1)\n");
00145          return -1;
00146       }
00147       pvt->samples += GSM_SAMPLES;
00148       pvt->datalen += 2 * GSM_SAMPLES;
00149       if (flen == MSGSM_FRAME_LEN) {
00150          if (gsm_decode(tmp->gsm, data + GSM_FRAME_LEN, dst + pvt->samples)) {
00151             ast_log(LOG_WARNING, "Invalid GSM data (2)\n");
00152             return -1;
00153          }
00154          pvt->samples += GSM_SAMPLES;
00155          pvt->datalen += 2 * GSM_SAMPLES;
00156       }
00157    }
00158    return 0;
00159 }

static struct ast_frame* gsmtolin_sample ( void   )  [static]

Definition at line 97 of file codec_gsm.c.

References AST_FORMAT_GSM, AST_FRAME_VOICE, f, GSM_SAMPLES, and gsm_slin_ex.

00098 {
00099    static struct ast_frame f;
00100    f.frametype = AST_FRAME_VOICE;
00101    f.subclass = AST_FORMAT_GSM;
00102    f.datalen = sizeof(gsm_slin_ex);
00103    /* All frames are 20 ms long */
00104    f.samples = GSM_SAMPLES;
00105    f.mallocd = 0;
00106    f.offset = 0;
00107    f.src = __PRETTY_FUNCTION__;
00108    f.data = gsm_slin_ex;
00109    return &f;
00110 }

static int lintogsm_framein ( struct ast_trans_pvt pvt,
struct ast_frame f 
) [static]

store samples into working buffer for later decode

Definition at line 162 of file codec_gsm.c.

References ast_log(), gsm_translator_pvt::buf, BUFFER_SAMPLES, f, LOG_WARNING, ast_trans_pvt::pvt, and ast_trans_pvt::samples.

00163 {
00164    struct gsm_translator_pvt *tmp = pvt->pvt;
00165 
00166    /* XXX We should look at how old the rest of our stream is, and if it
00167       is too old, then we should overwrite it entirely, otherwise we can
00168       get artifacts of earlier talk that do not belong */
00169    if (pvt->samples + f->samples > BUFFER_SAMPLES) {
00170       ast_log(LOG_WARNING, "Out of buffer space\n");
00171       return -1;
00172    }
00173    memcpy(tmp->buf + pvt->samples, f->data, f->datalen);
00174    pvt->samples += f->samples;
00175    return 0;
00176 }

static struct ast_frame* lintogsm_frameout ( struct ast_trans_pvt pvt  )  [static]

encode and produce a frame

Definition at line 179 of file codec_gsm.c.

References ast_trans_frameout(), gsm_translator_pvt::buf, gsm_translator_pvt::gsm, GSM_FRAME_LEN, GSM_SAMPLES, ast_trans_pvt::outbuf, ast_trans_pvt::pvt, and ast_trans_pvt::samples.

00180 {
00181    struct gsm_translator_pvt *tmp = pvt->pvt;
00182    int datalen = 0;
00183    int samples = 0;
00184 
00185    /* We can't work on anything less than a frame in size */
00186    if (pvt->samples < GSM_SAMPLES)
00187       return NULL;
00188    while (pvt->samples >= GSM_SAMPLES) {
00189       /* Encode a frame of data */
00190       gsm_encode(tmp->gsm, tmp->buf + samples, (gsm_byte *) pvt->outbuf + datalen);
00191       datalen += GSM_FRAME_LEN;
00192       samples += GSM_SAMPLES;
00193       pvt->samples -= GSM_SAMPLES;
00194    }
00195 
00196    /* Move the data at the end of the buffer to the front */
00197    if (pvt->samples)
00198       memmove(tmp->buf, tmp->buf + samples, pvt->samples * 2);
00199 
00200    return ast_trans_frameout(pvt, datalen, samples);
00201 }

static struct ast_frame* lintogsm_sample ( void   )  [static]

Definition at line 82 of file codec_gsm.c.

References AST_FORMAT_SLINEAR, AST_FRAME_VOICE, f, and slin_gsm_ex.

00083 {
00084    static struct ast_frame f;
00085    f.frametype = AST_FRAME_VOICE;
00086    f.subclass = AST_FORMAT_SLINEAR;
00087    f.datalen = sizeof(slin_gsm_ex);
00088    /* Assume 8000 Hz */
00089    f.samples = sizeof(slin_gsm_ex)/2;
00090    f.mallocd = 0;
00091    f.offset = 0;
00092    f.src = __PRETTY_FUNCTION__;
00093    f.data = slin_gsm_ex;
00094    return &f;
00095 }

static int load_module ( void   )  [static]

Definition at line 253 of file codec_gsm.c.

References ast_register_translator, ast_unregister_translator(), gsmtolin, and lintogsm.

00254 {
00255    int res;
00256 
00257    res = ast_register_translator(&gsmtolin);
00258    if (!res) 
00259       res=ast_register_translator(&lintogsm);
00260    else
00261       ast_unregister_translator(&gsmtolin);
00262 
00263    return res;
00264 }

static int reload ( void   )  [static]

standard module glue

Definition at line 237 of file codec_gsm.c.

00238 {
00239    return 0;
00240 }

static int unload_module ( void   )  [static]

Definition at line 242 of file codec_gsm.c.

References ast_unregister_translator(), gsmtolin, and lintogsm.

00243 {
00244    int res;
00245 
00246    res = ast_unregister_translator(&lintogsm);
00247    if (!res)
00248       res = ast_unregister_translator(&gsmtolin);
00249 
00250    return res;
00251 }


Variable Documentation

struct ast_module_info __mod_info = { .name = AST_MODULE, .flags = AST_MODFLAG_DEFAULT | AST_MODFLAG_BUILDSUM, .description = "GSM Coder/Decoder" , .key = "This paragraph is copyright (c) 2006 by Digium, Inc. \In order for your module to load, it must return this \key via a function called \"key\". Any code which \includes this paragraph must be licensed under the GNU \General Public License version 2 or later (at your \option). In addition to Digium's general reservations \of rights, Digium expressly reserves the right to \allow other parties to license this paragraph under \different terms. Any use of Digium, Inc. trademarks or \logos (including \"Asterisk\" or \"Digium\") without \express written permission of Digium, Inc. is prohibited.\n" , .buildopt_sum = "361d7bb937402d51e4658efb5b4d76e4" , .load = load_module, .unload = unload_module, .reload = reload, } [static]

Definition at line 270 of file codec_gsm.c.

const struct ast_module_info* ast_module_info = &__mod_info [static]

Definition at line 270 of file codec_gsm.c.

struct ast_translator gsmtolin [static]

Definition at line 210 of file codec_gsm.c.

Referenced by load_module(), and unload_module().

struct ast_translator lintogsm [static]

Definition at line 223 of file codec_gsm.c.

Referenced by load_module(), and unload_module().


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