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
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.
static struct ast_frame *	lintoadpcm_frameout (struct ast_trans_pvt *pvt)
	convert inbuf and store into frame
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 = ASTERISK_GPL_KEY , .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.

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 adpcm_decoder_pvt::state.

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, adpcm_encoder_pvt::inbuf, ast_frame::ptr, ast_trans_pvt::pvt, ast_frame::samples, and ast_trans_pvt::samples.

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, adpcm_encoder_pvt::inbuf, NULL, ast_trans_pvt::outbuf, ast_trans_pvt::pvt, ast_frame::samples, ast_trans_pvt::samples, and adpcm_encoder_pvt::state.

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 = ASTERISK_GPL_KEY , .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.

                                          {
    .name = "adpcmtolin",
    .src_codec = {
        .name = "adpcm",
        .type = AST_MEDIA_TYPE_AUDIO,
        .sample_rate = 8000,
    },
    .dst_codec = {
        .name = "slin",
        .type = AST_MEDIA_TYPE_AUDIO,
        .sample_rate = 8000,
    },
    .format = "slin",
    .framein = adpcmtolin_framein,
    .sample = adpcm_sample,
    .desc_size = sizeof(struct adpcm_decoder_pvt),
    .buffer_samples = BUFFER_SAMPLES,
    .buf_size = BUFFER_SAMPLES * 2,
};

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.

{ -1, -1, -1, -1, 2, 4, 6, 8 };

Referenced by decode().

lintoadpcm

struct ast_translator lintoadpcm

static

Definition at line 309 of file codec_adpcm.c.

                                          {
    .name = "lintoadpcm",
    .src_codec = {
        .name = "slin",
        .type = AST_MEDIA_TYPE_AUDIO,
        .sample_rate = 8000,
    },
    .dst_codec = {
        .name = "adpcm",
        .type = AST_MEDIA_TYPE_AUDIO,
        .sample_rate = 8000,
    },
    .format = "adpcm",
    .framein = lintoadpcm_framein,
    .frameout = lintoadpcm_frameout,
    .sample = slin8_sample,
    .desc_size = sizeof (struct adpcm_encoder_pvt),
    .buffer_samples = BUFFER_SAMPLES,
    .buf_size = BUFFER_SAMPLES/ 2,  /* 2 samples per byte */
};

Referenced by load_module(), and unload_module().

stpsz

int stpsz[49]

static

Definition at line 62 of file codec_adpcm.c.

                       {
  16, 17, 19, 21, 23, 25, 28, 31, 34, 37, 41, 45, 50, 55, 60, 66, 73,
  80, 88, 97, 107, 118, 130, 143, 157, 173, 190, 209, 230, 253, 279,
  307, 337, 371, 408, 449, 494, 544, 598, 658, 724, 796, 876, 963,
  1060, 1166, 1282, 1411, 1552
};

Referenced by adpcm(), and decode().