Thu Apr 28 2011 16:57:08

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 "asterisk/translate.h"
#include "asterisk/config.h"
#include "asterisk/module.h"
#include "asterisk/utils.h"
#include "../formats/msgsm.h"
#include "asterisk/slin.h"
#include "ex_gsm.h"
Include dependency graph for codec_gsm.c:

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 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 int load_module (void)
static int reload (void)
 standard module glue
static int unload_module (void)

Variables

static struct ast_module_info
__MODULE_INFO_SECTION 
__mod_info = { __MODULE_INFO_GLOBALS .name = AST_MODULE, .flags = AST_MODFLAG_DEFAULT , .description = "GSM Coder/Decoder" , .key = ASTERISK_GPL_KEY , .buildopt_sum = AST_BUILDOPT_SUM, .load = load_module, .unload = unload_module, .reload = reload, }
static 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 50 of file codec_gsm.c.

Referenced by gsmtolin_framein(), and lintogsm_framein().

#define GSM_FRAME_LEN   33

Definition at line 52 of file codec_gsm.c.

Referenced by gsmtolin_framein(), and lintogsm_frameout().

#define GSM_SAMPLES   160

Definition at line 51 of file codec_gsm.c.

Referenced by gsm_sample(), gsmtolin_framein(), and lintogsm_frameout().

#define MSGSM_FRAME_LEN   65

Definition at line 53 of file codec_gsm.c.

Referenced by gsmtolin_framein().


Function Documentation

static void __reg_module ( void  ) [static]

Definition at line 230 of file codec_gsm.c.

static void __unreg_module ( void  ) [static]

Definition at line 230 of file codec_gsm.c.

static void gsm_destroy_stuff ( struct ast_trans_pvt pvt) [static]

Definition at line 162 of file codec_gsm.c.

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

{
   struct gsm_translator_pvt *tmp = pvt->pvt;
   if (tmp->gsm)
      gsm_destroy(tmp->gsm);
}
static int gsm_new ( struct ast_trans_pvt pvt) [static]

Definition at line 64 of file codec_gsm.c.

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

{
   struct gsm_translator_pvt *tmp = pvt->pvt;
   
   return (tmp->gsm = gsm_create()) ? 0 : -1;
}
static int gsmtolin_framein ( struct ast_trans_pvt pvt,
struct ast_frame f 
) [static]

decode and store in outbuf.

Definition at line 72 of file codec_gsm.c.

References ast_log(), BUFFER_SAMPLES, conv65(), ast_frame::data, ast_trans_pvt::datalen, ast_frame::datalen, gsm_translator_pvt::gsm, GSM_FRAME_LEN, GSM_SAMPLES, ast_trans_pvt::i16, len(), LOG_WARNING, MSGSM_FRAME_LEN, ast_trans_pvt::outbuf, ast_frame::ptr, ast_trans_pvt::pvt, and ast_trans_pvt::samples.

{
   struct gsm_translator_pvt *tmp = pvt->pvt;
   int x;
   int16_t *dst = pvt->outbuf.i16;
   /* guess format from frame len. 65 for MSGSM, 33 for regular GSM */
   int flen = (f->datalen % MSGSM_FRAME_LEN == 0) ?
      MSGSM_FRAME_LEN : GSM_FRAME_LEN;

   for (x=0; x < f->datalen; x += flen) {
      unsigned char data[2 * GSM_FRAME_LEN];
      unsigned char *src;
      int len;
      if (flen == MSGSM_FRAME_LEN) {
         len = 2*GSM_SAMPLES;
         src = data;
         /* Translate MSGSM format to Real GSM format before feeding in */
         /* XXX what's the point here! we should just work
          * on the full format.
          */
         conv65(f->data.ptr + x, data);
      } else {
         len = GSM_SAMPLES;
         src = f->data.ptr + x;
      }
      /* XXX maybe we don't need to check */
      if (pvt->samples + len > BUFFER_SAMPLES) {   
         ast_log(LOG_WARNING, "Out of buffer space\n");
         return -1;
      }
      if (gsm_decode(tmp->gsm, src, dst + pvt->samples)) {
         ast_log(LOG_WARNING, "Invalid GSM data (1)\n");
         return -1;
      }
      pvt->samples += GSM_SAMPLES;
      pvt->datalen += 2 * GSM_SAMPLES;
      if (flen == MSGSM_FRAME_LEN) {
         if (gsm_decode(tmp->gsm, data + GSM_FRAME_LEN, dst + pvt->samples)) {
            ast_log(LOG_WARNING, "Invalid GSM data (2)\n");
            return -1;
         }
         pvt->samples += GSM_SAMPLES;
         pvt->datalen += 2 * GSM_SAMPLES;
      }
   }
   return 0;
}
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 121 of file codec_gsm.c.

References ast_log(), gsm_translator_pvt::buf, BUFFER_SAMPLES, ast_frame::data, ast_frame::datalen, LOG_WARNING, ast_frame::ptr, ast_trans_pvt::pvt, ast_frame::samples, and ast_trans_pvt::samples.

{
   struct gsm_translator_pvt *tmp = pvt->pvt;

   /* XXX We should look at how old the rest of our stream is, and if it
      is too old, then we should overwrite it entirely, otherwise we can
      get artifacts of earlier talk that do not belong */
   if (pvt->samples + f->samples > BUFFER_SAMPLES) {
      ast_log(LOG_WARNING, "Out of buffer space\n");
      return -1;
   }
   memcpy(tmp->buf + pvt->samples, f->data.ptr, f->datalen);
   pvt->samples += f->samples;
   return 0;
}
static struct ast_frame* lintogsm_frameout ( struct ast_trans_pvt pvt) [static, read]

encode and produce a frame

Definition at line 138 of file codec_gsm.c.

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

{
   struct gsm_translator_pvt *tmp = pvt->pvt;
   int datalen = 0;
   int samples = 0;

   /* We can't work on anything less than a frame in size */
   if (pvt->samples < GSM_SAMPLES)
      return NULL;
   while (pvt->samples >= GSM_SAMPLES) {
      /* Encode a frame of data */
      gsm_encode(tmp->gsm, tmp->buf + samples, (gsm_byte *) pvt->outbuf.c + datalen);
      datalen += GSM_FRAME_LEN;
      samples += GSM_SAMPLES;
      pvt->samples -= GSM_SAMPLES;
   }

   /* Move the data at the end of the buffer to the front */
   if (pvt->samples)
      memmove(tmp->buf, tmp->buf + samples, pvt->samples * 2);

   return ast_trans_frameout(pvt, datalen, samples);
}
static int load_module ( void  ) [static]
static int reload ( void  ) [static]

standard module glue

Definition at line 196 of file codec_gsm.c.

References AST_MODULE_LOAD_SUCCESS.

static int unload_module ( void  ) [static]

Definition at line 201 of file codec_gsm.c.

References ast_unregister_translator().

{
   int res;

   res = ast_unregister_translator(&lintogsm);
   if (!res)
      res = ast_unregister_translator(&gsmtolin);

   return res;
}

Variable Documentation

struct ast_module_info __MODULE_INFO_SECTION __mod_info = { __MODULE_INFO_GLOBALS .name = AST_MODULE, .flags = AST_MODFLAG_DEFAULT , .description = "GSM Coder/Decoder" , .key = ASTERISK_GPL_KEY , .buildopt_sum = AST_BUILDOPT_SUM, .load = load_module, .unload = unload_module, .reload = reload, } [static]

Definition at line 230 of file codec_gsm.c.

Definition at line 230 of file codec_gsm.c.

struct ast_translator gsmtolin [static]

Definition at line 169 of file codec_gsm.c.

struct ast_translator lintogsm [static]

Definition at line 182 of file codec_gsm.c.