codec_adpcm.c File Reference

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

Macros
#define	BUFFER_SAMPLES   8096 /* size for the translation buffers */

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 More...
struct ast_module *	AST_MODULE_SELF_SYM (void)
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. More...
static struct ast_frame *	lintoadpcm_frameout (struct ast_trans_pvt *pvt)
	convert inbuf and store into frame More...
static int	load_module (void)
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, .support_level = AST_MODULE_SUPPORT_CORE, .load = load_module, .unload = unload_module, }
static struct ast_translator	adpcmtolin
static const 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.

Macro Definition Documentation

BUFFER_SAMPLES

#define BUFFER_SAMPLES   8096 /* size for the translation buffers */

Definition at line 46 of file codec_adpcm.c.

Function Documentation

__reg_module()

static void __reg_module ( void  )

static

Definition at line 359 of file codec_adpcm.c.

__unreg_module()

static void __unreg_module ( void  )

static

Definition at line 359 of file codec_adpcm.c.

adpcm()

static int adpcm ( short  csig, struct adpcm_state *  state  )

inlinestatic

Definition at line 164 of file codec_adpcm.c.

{
    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;
}

References decode(), and stpsz.

Referenced by lintoadpcm_frameout().

adpcmtolin_framein()

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 229 of file codec_adpcm.c.

{
    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;
}

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

AST_MODULE_SELF_SYM()

struct ast_module * AST_MODULE_SELF_SYM

(

void

)

Definition at line 359 of file codec_adpcm.c.

decode()

static short decode ( int  encoded, struct adpcm_state *  state  )

inlinestatic

Definition at line 91 of file codec_adpcm.c.

{
    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;
}

References indsft, and stpsz.

Referenced by adpcm(), and adpcmtolin_framein().

lintoadpcm_framein()

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 246 of file codec_adpcm.c.

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

References ast_frame::data, ast_frame::datalen, ast_frame::ptr, ast_trans_pvt::pvt, ast_frame::samples, ast_trans_pvt::samples, and tmp().

lintoadpcm_frameout()

static struct ast_frame * lintoadpcm_frameout ( struct ast_trans_pvt *  pvt )

static

convert inbuf and store into frame

Definition at line 256 of file codec_adpcm.c.

{
    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;
}

References adpcm(), ast_trans_frameout(), ast_trans_pvt::c, NULL, ast_trans_pvt::outbuf, ast_trans_pvt::pvt, ast_frame::samples, ast_trans_pvt::samples, and tmp().

load_module()

static int load_module ( void  )

static

Definition at line 340 of file codec_adpcm.c.

{
    int res = 0;
 
    res = ast_register_translator(&adpcmtolin);
    res |= ast_register_translator(&lintoadpcm);
 
    if (res) {
        unload_module();
        return AST_MODULE_LOAD_DECLINE;
    }
 
    return AST_MODULE_LOAD_SUCCESS;
}

References adpcmtolin, AST_MODULE_LOAD_DECLINE, AST_MODULE_LOAD_SUCCESS, ast_register_translator, lintoadpcm, and unload_module().

unload_module()

static int unload_module ( void  )

static

Definition at line 330 of file codec_adpcm.c.

{
    int res;
 
    res = ast_unregister_translator(&lintoadpcm);
    res |= ast_unregister_translator(&adpcmtolin);
 
    return res;
}

References adpcmtolin, ast_unregister_translator(), and lintoadpcm.

Referenced by load_module().

Variable Documentation

__mod_info

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, .support_level = AST_MODULE_SUPPORT_CORE, .load = load_module, .unload = unload_module, }

static

Definition at line 359 of file codec_adpcm.c.

adpcmtolin

struct ast_translator adpcmtolin

static

Definition at line 289 of file codec_adpcm.c.

Referenced by load_module(), and unload_module().

ast_module_info

const struct ast_module_info* ast_module_info = &__mod_info

static

Definition at line 359 of file codec_adpcm.c.

indsft

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

static

Definition at line 56 of file codec_adpcm.c.

Referenced by decode().

lintoadpcm

struct ast_translator lintoadpcm

static

Definition at line 309 of file codec_adpcm.c.

Referenced by load_module(), and unload_module().

stpsz

int stpsz[49]

static

Definition at line 62 of file codec_adpcm.c.

Referenced by adpcm(), and decode().