codec_adpcm.c - translate between signed linear and Dialogic ADPCM More...

#include "asterisk.h"
#include "asterisk/lock.h"
#include "asterisk/linkedlists.h"
#include "asterisk/module.h"
#include "asterisk/config.h"
#include "asterisk/translate.h"
#include "asterisk/utils.h"
#include "asterisk/slin.h"
#include "ex_adpcm.h"

Include dependency graph for codec_adpcm.c:

Go to the source code of this file.

Data Structures
struct	adpcm_decoder_pvt
	Workspace for translating ADPCM signals to signed linear. More...
struct	adpcm_encoder_pvt
	Workspace for translating signed linear signals to ADPCM. More...
struct	adpcm_state
Defines
#define	BUFFER_SAMPLES 8096
Functions
static void	__reg_module (void)
static void	__unreg_module (void)
static int	adpcm (short csig, struct adpcm_state *state)
static int	adpcmtolin_framein (struct ast_trans_pvt pvt, struct ast_frame f)
	decode 4-bit adpcm frame data and store in output buffer
static short	decode (int encoded, struct adpcm_state *state)
static int	lintoadpcm_framein (struct ast_trans_pvt pvt, struct ast_frame f)
	fill input buffer with 16-bit signed linear PCM values.
static struct ast_frame *	lintoadpcm_frameout (struct ast_trans_pvt *pvt)
	convert inbuf and store into frame
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 , .description = "Adaptive Differential PCM 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 = AST_BUILDOPT_SUM, .load = load_module, .unload = unload_module, .reload = reload, }
static struct ast_translator	adpcmtolin
static struct ast_module_info *	ast_module_info = &__mod_info
static int	indsft [8] = { -1, -1, -1, -1, 2, 4, 6, 8 }
static struct ast_translator	lintoadpcm
static int	stpsz [49]

Detailed Description

codec_adpcm.c - translate between signed linear and Dialogic ADPCM

Definition in file codec_adpcm.c.

Define Documentation

#define BUFFER_SAMPLES 8096

Definition at line 48 of file codec_adpcm.c.

Function Documentation

static void __reg_module ( void ) [static]

Definition at line 348 of file codec_adpcm.c.

static void __unreg_module ( void ) [static]

Definition at line 348 of file codec_adpcm.c.

static int adpcm	(	short	csig,
		struct adpcm_state *	state
	)		`[inline, static]`

Definition at line 166 of file codec_adpcm.c.

References decode(), adpcm_state::signal, and adpcm_state::ssindex.

Referenced by lintoadpcm_frameout().

{
   int diff;
   int step;
   int encoded;

   /* 
    * Clip csig if too large or too small
    */
   csig >>= 4;

   step = stpsz[state->ssindex];
   diff = csig - state->signal;

#ifdef NOT_BLI
   if (diff < 0) {
      encoded = (-diff << 2) / step;
      if (encoded > 7)
         encoded = 7;
      encoded |= 0x08;
   } else {
      encoded = (diff << 2) / step;
      if (encoded > 7)
         encoded = 7;
   }
#else /* BLI code */
   if (diff < 0) {
      encoded = 8;
      diff = -diff;
   } else
      encoded = 0;
   if (diff >= step) {
      encoded |= 4;
      diff -= step;
   }
   step >>= 1;
   if (diff >= step) {
      encoded |= 2;
      diff -= step;
   }
   step >>= 1;
   if (diff >= step)
      encoded |= 1;
#endif /* NOT_BLI */

   /* feedback to state */
   decode(encoded, state);
   
   return encoded;
}

static int adpcmtolin_framein	(	struct ast_trans_pvt *	pvt,
		struct ast_frame *	f
	)		`[static]`

decode 4-bit adpcm frame data and store in output buffer

Definition at line 231 of file codec_adpcm.c.

References ast_frame::data, ast_trans_pvt::datalen, ast_frame::datalen, decode(), ast_trans_pvt::i16, ast_trans_pvt::outbuf, ast_frame::ptr, ast_trans_pvt::pvt, ast_trans_pvt::samples, ast_frame::samples, and adpcm_decoder_pvt::state.

{
   struct adpcm_decoder_pvt *tmp = pvt->pvt;
   int x = f->datalen;
   unsigned char *src = f->data.ptr;
   int16_t *dst = pvt->outbuf.i16 + pvt->samples;

   while (x--) {
      *dst++ = decode((*src >> 4) & 0xf, &tmp->state);
      *dst++ = decode(*src++ & 0x0f, &tmp->state);
   }
   pvt->samples += f->samples;
   pvt->datalen += 2*f->samples;
   return 0;
}

static short decode	(	int	encoded,
		struct adpcm_state *	state
	)		`[inline, static]`

Definition at line 93 of file codec_adpcm.c.

References adpcm_state::next_flag, adpcm_state::signal, adpcm_state::ssindex, and adpcm_state::zero_count.

Referenced by adpcm(), and adpcmtolin_framein().

{
   int diff;
   int step;
   int sign;

   step = stpsz[state->ssindex];

   sign = encoded & 0x08;
   encoded &= 0x07;
#ifdef NOT_BLI
   diff = (((encoded << 1) + 1) * step) >> 3;
#else /* BLI code */
   diff = step >> 3;
   if (encoded & 4)
      diff += step;
   if (encoded & 2)
      diff += step >> 1;
   if (encoded & 1)
      diff += step >> 2;
   if ((encoded >> 1) & step & 0x1)
      diff++;
#endif
   if (sign)
      diff = -diff;

   if (state->next_flag & 0x1)
      state->signal -= 8;
   else if (state->next_flag & 0x2)
      state->signal += 8;

   state->signal += diff;

   if (state->signal > 2047)
      state->signal = 2047;
   else if (state->signal < -2047)
      state->signal = -2047;

   state->next_flag = 0;

#ifdef AUTO_RETURN
   if (encoded)
      state->zero_count = 0;
   else if (++(state->zero_count) == 24) {
      state->zero_count = 0;
      if (state->signal > 0)
         state->next_flag = 0x1;
      else if (state->signal < 0)
         state->next_flag = 0x2;
   }
#endif

   state->ssindex += indsft[encoded];
   if (state->ssindex < 0)
      state->ssindex = 0;
   else if (state->ssindex > 48)
      state->ssindex = 48;

   return state->signal << 4;
}

static int lintoadpcm_framein	(	struct ast_trans_pvt *	pvt,
		struct ast_frame *	f
	)		`[static]`

fill input buffer with 16-bit signed linear PCM values.

Definition at line 248 of file codec_adpcm.c.

References ast_frame::data, ast_frame::datalen, adpcm_encoder_pvt::inbuf, ast_frame::ptr, ast_trans_pvt::pvt, ast_trans_pvt::samples, and ast_frame::samples.

{
   struct adpcm_encoder_pvt *tmp = pvt->pvt;

   memcpy(&tmp->inbuf[pvt->samples], f->data.ptr, f->datalen);
   pvt->samples += f->samples;
   return 0;
}

static struct ast_frame* lintoadpcm_frameout ( struct ast_trans_pvt * pvt ) [static, read]

convert inbuf and store into frame

Definition at line 258 of file codec_adpcm.c.

References adpcm(), ast_trans_frameout(), ast_trans_pvt::c, f, adpcm_encoder_pvt::inbuf, ast_trans_pvt::outbuf, ast_trans_pvt::pvt, ast_trans_pvt::samples, ast_frame::samples, and adpcm_encoder_pvt::state.

{
   struct adpcm_encoder_pvt *tmp = pvt->pvt;
   struct ast_frame *f;
   int i;
   int samples = pvt->samples;   /* save original number */
  
   if (samples < 2)
      return NULL;

   pvt->samples &= ~1; /* atomic size is 2 samples */

   for (i = 0; i < pvt->samples; i += 2) {
      pvt->outbuf.c[i/2] =
         (adpcm(tmp->inbuf[i  ], &tmp->state) << 4) |
         (adpcm(tmp->inbuf[i+1], &tmp->state)     );
   };

   f = ast_trans_frameout(pvt, pvt->samples/2, 0);

   /*
    * If there is a left over sample, move it to the beginning
    * of the input buffer.
    */

   if (samples & 1) {   /* move the leftover sample at beginning */
      tmp->inbuf[0] = tmp->inbuf[samples - 1];
      pvt->samples = 1;
   }
   return f;
}

static int load_module ( void ) [static]

Definition at line 330 of file codec_adpcm.c.

References AST_MODULE_LOAD_FAILURE, AST_MODULE_LOAD_SUCCESS, ast_register_translator, and ast_unregister_translator().

{
   int res;

   res = ast_register_translator(&adpcmtolin);
   if (!res)
      res = ast_register_translator(&lintoadpcm);
   else
      ast_unregister_translator(&adpcmtolin);
   if (res)
      return AST_MODULE_LOAD_FAILURE;
   return AST_MODULE_LOAD_SUCCESS;
}

static int reload ( void ) [static]

standard module glue

Definition at line 315 of file codec_adpcm.c.

References AST_MODULE_LOAD_SUCCESS.

{
   return AST_MODULE_LOAD_SUCCESS;
}

static int unload_module ( void ) [static]

Definition at line 320 of file codec_adpcm.c.

References ast_unregister_translator().

{
   int res;

   res = ast_unregister_translator(&lintoadpcm);
   res |= ast_unregister_translator(&adpcmtolin);

   return res;
}

Variable Documentation

struct ast_module_info __mod_info = { .name = AST_MODULE, .flags = AST_MODFLAG_DEFAULT , .description = "Adaptive Differential PCM 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 = AST_BUILDOPT_SUM, .load = load_module, .unload = unload_module, .reload = reload, } [static]

Definition at line 348 of file codec_adpcm.c.

struct ast_translator adpcmtolin [static]

Definition at line 291 of file codec_adpcm.c.

struct ast_module_info* ast_module_info = &__mod_info [static]

Definition at line 348 of file codec_adpcm.c.

int indsft[8] = { -1, -1, -1, -1, 2, 4, 6, 8 } [static]

Definition at line 58 of file codec_adpcm.c.

struct ast_translator lintoadpcm [static]

Definition at line 302 of file codec_adpcm.c.

int stpsz[49] [static]

Definition at line 64 of file codec_adpcm.c.