Tue Nov 4 13:20:36 2008

Asterisk developer's documentation


codec_g726.c File Reference

codec_g726.c - translate between signed linear and ITU G.726-32kbps (both RFC3551 and AAL2 codeword packing) More...

#include "asterisk.h"
#include <fcntl.h>
#include <netinet/in.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include "asterisk/lock.h"
#include "asterisk/logger.h"
#include "asterisk/linkedlists.h"
#include "asterisk/module.h"
#include "asterisk/config.h"
#include "asterisk/options.h"
#include "asterisk/translate.h"
#include "asterisk/channel.h"
#include "asterisk/utils.h"
#include "log2comp.h"
#include "slin_g726_ex.h"
#include "g726_slin_ex.h"

Go to the source code of this file.

Data Structures

struct  g726_coder_pvt
struct  g726_state

Defines

#define BUF_SHIFT   5
#define BUFFER_SAMPLES   8096
#define WANT_ASM

Functions

 AST_MODULE_INFO (ASTERISK_GPL_KEY, AST_MODFLAG_DEFAULT,"ITU G.726-32kbps G726 Transcoder",.load=load_module,.unload=unload_module,.reload=reload,)
static int fmult (int an, int srn)
static int g726_decode (int i, struct g726_state *state_ptr)
static int g726_encode (int sl, struct g726_state *state_ptr)
static void g726_init_state (struct g726_state *state_ptr)
static int g726aal2tolin_framein (struct ast_trans_pvt *pvt, struct ast_frame *f)
 decode packed 4-bit G726 values (AAL2 packing) and store in buffer.
static int g726tog726aal2_framein (struct ast_trans_pvt *pvt, struct ast_frame *f)
 convert G726-32 RFC3551 packed data into AAL2 packed data (or vice-versa)
static int g726tolin_framein (struct ast_trans_pvt *pvt, struct ast_frame *f)
 decode packed 4-bit G726 values (RFC3551 packing) and store in buffer.
static struct ast_frameg726tolin_sample (void)
static int lintog726_framein (struct ast_trans_pvt *pvt, struct ast_frame *f)
 compress and store data (4-bit G726 samples, RFC3551 packing) in outbuf
static int lintog726_new (struct ast_trans_pvt *pvt)
 init a new instance of g726_coder_pvt.
static struct ast_framelintog726_sample (void)
static int lintog726aal2_framein (struct ast_trans_pvt *pvt, struct ast_frame *f)
 compress and store data (4-bit G726 samples, AAL2 packing) in outbuf
static int load_module (void)
static void parse_config (void)
static int predictor_pole (struct g726_state *state_ptr)
static int predictor_zero (struct g726_state *state_ptr)
static int quan (int val, int *table, int size)
static int quantize (int d, int y, int *table, int size)
static int reconstruct (int sign, int dqln, int y)
static int reload (void)
static int step_size (struct g726_state *state_ptr)
static int unload_module (void)
static void update (int code_size, int y, int wi, int fi, int dq, int sr, int dqsez, struct g726_state *state_ptr)

Variables

static int _dqlntab [16]
static int _fitab [16]
static int _witab [16]
static struct ast_translator g726aal2tog726
static struct ast_translator g726aal2tolin
static struct ast_translator g726tog726aal2
static struct ast_translator g726tolin
static struct ast_translator lintog726
static struct ast_translator lintog726aal2
static int qtab_721 [7] = {-124, 80, 178, 246, 300, 349, 400}


Detailed Description

codec_g726.c - translate between signed linear and ITU G.726-32kbps (both RFC3551 and AAL2 codeword packing)

Definition in file codec_g726.c.


Define Documentation

#define BUF_SHIFT   5

Definition at line 68 of file codec_g726.c.

#define BUFFER_SAMPLES   8096

Definition at line 67 of file codec_g726.c.

#define WANT_ASM

Definition at line 51 of file codec_g726.c.


Function Documentation

AST_MODULE_INFO ( ASTERISK_GPL_KEY  ,
AST_MODFLAG_DEFAULT  ,
"ITU G.726-32kbps G726 Transcoder"  ,
load = load_module,
unload = unload_module,
reload = reload 
)

static int fmult ( int  an,
int  srn 
) [static]

Definition at line 214 of file codec_g726.c.

References ilog2().

Referenced by predictor_pole(), and predictor_zero().

00215 {
00216    int      anmag, anexp, anmant;
00217    int      wanexp, wanmant;
00218    int      retval;
00219 
00220    anmag = (an > 0) ? an : ((-an) & 0x1FFF);
00221    anexp = ilog2(anmag) - 5;
00222    anmant = (anmag == 0) ? 32 :
00223        (anexp >= 0) ? anmag >> anexp : anmag << -anexp;
00224    wanexp = anexp + ((srn >> 6) & 0xF) - 13;
00225 
00226    wanmant = (anmant * (srn & 077) + 0x30) >> 4;
00227    retval = (wanexp >= 0) ? ((wanmant << wanexp) & 0x7FFF) :
00228        (wanmant >> -wanexp);
00229 
00230    return (((an ^ srn) < 0) ? -retval : retval);
00231 }

static int g726_decode ( int  i,
struct g726_state state_ptr 
) [static]

Definition at line 587 of file codec_g726.c.

References predictor_pole(), predictor_zero(), reconstruct(), step_size(), and update().

Referenced by g726aal2tolin_framein(), and g726tolin_framein().

00588 {
00589    int      sezi, sez, se; /* ACCUM */
00590    int      y;       /* MIX */
00591    int      sr;         /* ADDB */
00592    int      dq;
00593    int      dqsez;
00594 
00595    i &= 0x0f;        /* mask to get proper bits */
00596 #ifdef NOT_BLI
00597    sezi = predictor_zero(state_ptr);
00598    sez = sezi;
00599    se = sezi + predictor_pole(state_ptr); /* estimated signal */
00600 #else
00601    sezi = predictor_zero(state_ptr);
00602    sez = sezi >> 1;
00603    se = (sezi + predictor_pole(state_ptr)) >> 1;   /* estimated signal */
00604 #endif
00605 
00606    y = step_size(state_ptr);  /* dynamic quantizer step size */
00607 
00608    dq = reconstruct(i & 8, _dqlntab[i], y); /* quantized diff. */
00609 
00610 #ifdef NOT_BLI
00611    sr = se + dq;           /* reconst. signal */
00612    dqsez = dq + sez;       /* pole prediction diff. */
00613 #else
00614    sr = (dq < 0) ? se - (dq & 0x3FFF) : se + dq;   /* reconst. signal */
00615    dqsez = sr - se + sez;     /* pole prediction diff. */
00616 #endif
00617 
00618    update(4, y, _witab[i] << 5, _fitab[i], dq, sr, dqsez, state_ptr);
00619 
00620 #ifdef NOT_BLI
00621    return (sr >> 10);   /* sr was 26-bit dynamic range */
00622 #else
00623    return (sr << 2); /* sr was 14-bit dynamic range */
00624 #endif
00625 }

static int g726_encode ( int  sl,
struct g726_state state_ptr 
) [static]

Definition at line 633 of file codec_g726.c.

References predictor_pole(), predictor_zero(), quantize(), reconstruct(), step_size(), and update().

Referenced by lintog726_framein(), and lintog726aal2_framein().

00634 {
00635    int      sezi, se, sez;    /* ACCUM */
00636    int      d;       /* SUBTA */
00637    int      sr;         /* ADDB */
00638    int      y;       /* MIX */
00639    int      dqsez;         /* ADDC */
00640    int      dq, i;
00641 
00642 #ifdef NOT_BLI
00643    sl <<= 10;        /* 26-bit dynamic range */
00644 
00645    sezi = predictor_zero(state_ptr);
00646    sez = sezi;
00647    se = sezi + predictor_pole(state_ptr); /* estimated signal */
00648 #else
00649    sl >>= 2;         /* 14-bit dynamic range */
00650 
00651    sezi = predictor_zero(state_ptr);
00652    sez = sezi >> 1;
00653    se = (sezi + predictor_pole(state_ptr)) >> 1;   /* estimated signal */
00654 #endif
00655 
00656    d = sl - se;            /* estimation difference */
00657 
00658    /* quantize the prediction difference */
00659    y = step_size(state_ptr);     /* quantizer step size */
00660 #ifdef NOT_BLI
00661    d /= 0x1000;
00662 #endif
00663    i = quantize(d, y, qtab_721, 7); /* i = G726 code */
00664 
00665    dq = reconstruct(i & 8, _dqlntab[i], y);  /* quantized est diff */
00666 
00667 #ifdef NOT_BLI
00668    sr = se + dq;           /* reconst. signal */
00669    dqsez = dq + sez;       /* pole prediction diff. */
00670 #else
00671    sr = (dq < 0) ? se - (dq & 0x3FFF) : se + dq;   /* reconst. signal */
00672    dqsez = sr - se + sez;        /* pole prediction diff. */
00673 #endif
00674 
00675    update(4, y, _witab[i] << 5, _fitab[i], dq, sr, dqsez, state_ptr);
00676 
00677    return (i);
00678 }

static void g726_init_state ( struct g726_state state_ptr  )  [static]

Definition at line 132 of file codec_g726.c.

References g726_state::a, g726_state::ap, g726_state::b, g726_state::dml, g726_state::dms, g726_state::dq, g726_state::pk, g726_state::sr, g726_state::td, g726_state::yl, and g726_state::yu.

Referenced by lintog726_new().

00133 {
00134    int      cnta;
00135 
00136    state_ptr->yl = 34816;
00137    state_ptr->yu = 544;
00138    state_ptr->dms = 0;
00139    state_ptr->dml = 0;
00140    state_ptr->ap = 0;
00141    for (cnta = 0; cnta < 2; cnta++) {
00142       state_ptr->a[cnta] = 0;
00143       state_ptr->pk[cnta] = 0;
00144 #ifdef NOT_BLI
00145       state_ptr->sr[cnta] = 1;
00146 #else
00147       state_ptr->sr[cnta] = 32;
00148 #endif
00149    }
00150    for (cnta = 0; cnta < 6; cnta++) {
00151       state_ptr->b[cnta] = 0;
00152 #ifdef NOT_BLI
00153       state_ptr->dq[cnta] = 1;
00154 #else
00155       state_ptr->dq[cnta] = 32;
00156 #endif
00157    }
00158    state_ptr->td = 0;
00159 }

static int g726aal2tolin_framein ( struct ast_trans_pvt pvt,
struct ast_frame f 
) [static]

decode packed 4-bit G726 values (AAL2 packing) and store in buffer.

Definition at line 702 of file codec_g726.c.

References ast_trans_pvt::datalen, f, g726_coder_pvt::g726, g726_decode(), ast_trans_pvt::outbuf, ast_trans_pvt::pvt, and ast_trans_pvt::samples.

00703 {
00704    struct g726_coder_pvt *tmp = pvt->pvt;
00705    unsigned char *src = f->data;
00706    int16_t *dst = (int16_t *) pvt->outbuf + pvt->samples;
00707    unsigned int i;
00708 
00709    for (i = 0; i < f->datalen; i++) {
00710       *dst++ = g726_decode((src[i] >> 4) & 0xf, &tmp->g726);
00711       *dst++ = g726_decode(src[i] & 0x0f, &tmp->g726);
00712    }
00713 
00714    pvt->samples += f->samples;
00715    pvt->datalen += 2 * f->samples; /* 2 bytes/sample */
00716 
00717    return 0;
00718 }

static int g726tog726aal2_framein ( struct ast_trans_pvt pvt,
struct ast_frame f 
) [static]

convert G726-32 RFC3551 packed data into AAL2 packed data (or vice-versa)

Definition at line 784 of file codec_g726.c.

References ast_trans_pvt::datalen, f, ast_trans_pvt::outbuf, and ast_trans_pvt::samples.

00785 {
00786    unsigned char *src = f->data;
00787    unsigned char *dst = (unsigned char *) pvt->outbuf + pvt->samples;
00788    unsigned int i;
00789 
00790    for (i = 0; i < f->datalen; i++)
00791       *dst++ = ((src[i] & 0xf) << 4) | (src[i] >> 4);
00792 
00793    pvt->samples += f->samples;
00794    pvt->datalen += f->samples; /* 1 byte/sample */
00795 
00796    return 0;
00797 }

static int g726tolin_framein ( struct ast_trans_pvt pvt,
struct ast_frame f 
) [static]

decode packed 4-bit G726 values (RFC3551 packing) and store in buffer.

Definition at line 743 of file codec_g726.c.

References ast_trans_pvt::datalen, f, g726_coder_pvt::g726, g726_decode(), ast_trans_pvt::outbuf, ast_trans_pvt::pvt, and ast_trans_pvt::samples.

00744 {
00745    struct g726_coder_pvt *tmp = pvt->pvt;
00746    unsigned char *src = f->data;
00747    int16_t *dst = (int16_t *) pvt->outbuf + pvt->samples;
00748    unsigned int i;
00749 
00750    for (i = 0; i < f->datalen; i++) {
00751       *dst++ = g726_decode(src[i] & 0x0f, &tmp->g726);
00752       *dst++ = g726_decode((src[i] >> 4) & 0xf, &tmp->g726);
00753    }
00754 
00755    pvt->samples += f->samples;
00756    pvt->datalen += 2 * f->samples; /* 2 bytes/sample */
00757 
00758    return 0;
00759 }

static struct ast_frame* g726tolin_sample ( void   )  [static]

Definition at line 799 of file codec_g726.c.

References AST_FORMAT_G726, AST_FRAME_VOICE, f, g726_slin_ex, and ast_frame::samples.

00800 {
00801    static struct ast_frame f = {
00802       .frametype = AST_FRAME_VOICE,
00803       .subclass = AST_FORMAT_G726,
00804       .datalen = sizeof(g726_slin_ex),
00805       .samples = sizeof(g726_slin_ex) * 2,   /* 2 samples per byte */
00806       .src = __PRETTY_FUNCTION__,
00807       .data = g726_slin_ex,
00808    };
00809 
00810    return &f;
00811 }

static int lintog726_framein ( struct ast_trans_pvt pvt,
struct ast_frame f 
) [static]

compress and store data (4-bit G726 samples, RFC3551 packing) in outbuf

Definition at line 762 of file codec_g726.c.

References ast_trans_pvt::datalen, f, g726_coder_pvt::g726, g726_encode(), g726_coder_pvt::next_flag, ast_trans_pvt::outbuf, ast_trans_pvt::pvt, and ast_trans_pvt::samples.

00763 {
00764    struct g726_coder_pvt *tmp = pvt->pvt;
00765    int16_t *src = f->data;
00766    unsigned int i;
00767 
00768    for (i = 0; i < f->samples; i++) {
00769       unsigned char d = g726_encode(src[i], &tmp->g726); /* this sample */
00770 
00771       if (tmp->next_flag & 0x80) {  /* merge with leftover sample */
00772          pvt->outbuf[pvt->datalen++] = (d << 4) | (tmp->next_flag & 0xf);
00773          pvt->samples += 2;   /* 2 samples per byte */
00774          tmp->next_flag = 0;
00775       } else {
00776          tmp->next_flag = 0x80 | d;
00777       }
00778    }
00779 
00780    return 0;
00781 }

static int lintog726_new ( struct ast_trans_pvt pvt  )  [static]

init a new instance of g726_coder_pvt.

Definition at line 692 of file codec_g726.c.

References g726_coder_pvt::g726, g726_init_state(), and ast_trans_pvt::pvt.

00693 {
00694    struct g726_coder_pvt *tmp = pvt->pvt;
00695 
00696    g726_init_state(&tmp->g726);
00697 
00698    return 0;
00699 }

static struct ast_frame* lintog726_sample ( void   )  [static]

Definition at line 813 of file codec_g726.c.

References AST_FORMAT_SLINEAR, AST_FRAME_VOICE, f, ast_frame::samples, and slin_g726_ex.

00814 {
00815    static struct ast_frame f = {
00816       .frametype = AST_FRAME_VOICE,
00817       .subclass = AST_FORMAT_SLINEAR,
00818       .datalen = sizeof(slin_g726_ex),
00819       .samples = sizeof(slin_g726_ex) / 2,   /* 1 sample per 2 bytes */
00820       .src = __PRETTY_FUNCTION__,
00821       .data = slin_g726_ex,
00822    };
00823 
00824    return &f;
00825 }

static int lintog726aal2_framein ( struct ast_trans_pvt pvt,
struct ast_frame f 
) [static]

compress and store data (4-bit G726 samples, AAL2 packing) in outbuf

Definition at line 721 of file codec_g726.c.

References ast_trans_pvt::datalen, f, g726_coder_pvt::g726, g726_encode(), g726_coder_pvt::next_flag, ast_trans_pvt::outbuf, ast_trans_pvt::pvt, and ast_trans_pvt::samples.

00722 {
00723    struct g726_coder_pvt *tmp = pvt->pvt;
00724    int16_t *src = f->data;
00725    unsigned int i;
00726 
00727    for (i = 0; i < f->samples; i++) {
00728       unsigned char d = g726_encode(src[i], &tmp->g726); /* this sample */
00729 
00730       if (tmp->next_flag & 0x80) {  /* merge with leftover sample */
00731          pvt->outbuf[pvt->datalen++] = ((tmp->next_flag & 0xf)<< 4) | d;
00732          pvt->samples += 2;   /* 2 samples per byte */
00733          tmp->next_flag = 0;
00734       } else {
00735          tmp->next_flag = 0x80 | d;
00736       }
00737    }
00738 
00739    return 0;
00740 }

static int load_module ( void   )  [static]

Definition at line 938 of file codec_g726.c.

References ast_register_translator, g726aal2tog726, g726aal2tolin, g726tog726aal2, g726tolin, lintog726, lintog726aal2, parse_config(), and unload_module().

00939 {
00940    int res = 0;
00941 
00942 
00943    parse_config();
00944 
00945    res |= ast_register_translator(&g726tolin);
00946    res |= ast_register_translator(&lintog726);
00947 
00948    res |= ast_register_translator(&g726aal2tolin);
00949    res |= ast_register_translator(&lintog726aal2);
00950 
00951    res |= ast_register_translator(&g726aal2tog726);
00952    res |= ast_register_translator(&g726tog726aal2);
00953 
00954    if (res)
00955       unload_module();
00956 
00957    return res;
00958 }

static void parse_config ( void   )  [static]

Definition at line 897 of file codec_g726.c.

References ast_config_load(), ast_true(), ast_variable_browse(), ast_verbose(), g726tolin, option_verbose, ast_translator::useplc, var, and VERBOSE_PREFIX_3.

00898 {
00899    struct ast_variable *var;
00900    struct ast_config *cfg = ast_config_load("codecs.conf");
00901 
00902    if (!cfg)
00903       return;
00904    for (var = ast_variable_browse(cfg, "plc"); var; var = var->next) {
00905       if (!strcasecmp(var->name, "genericplc")) {
00906          g726tolin.useplc = ast_true(var->value) ? 1 : 0;
00907          if (option_verbose > 2)
00908             ast_verbose(VERBOSE_PREFIX_3 "codec_g726: %susing generic PLC\n",
00909                g726tolin.useplc ? "" : "not ");
00910       }
00911    }
00912    ast_config_destroy(cfg);
00913 }

static int predictor_pole ( struct g726_state state_ptr  )  [static]

Definition at line 242 of file codec_g726.c.

References g726_state::a, fmult(), and g726_state::sr.

Referenced by g726_decode(), and g726_encode().

00243 {
00244    return (fmult(state_ptr->a[1] >> 2, state_ptr->sr[1]) +
00245          fmult(state_ptr->a[0] >> 2, state_ptr->sr[0]));
00246 }

static int predictor_zero ( struct g726_state state_ptr  )  [static]

Definition at line 233 of file codec_g726.c.

References g726_state::b, g726_state::dq, and fmult().

Referenced by g726_decode(), and g726_encode().

00234 {
00235    int      i;
00236    int      sezi;
00237    for (sezi = 0, i = 0; i < 6; i++)         /* ACCUM */
00238       sezi += fmult(state_ptr->b[i] >> 2, state_ptr->dq[i]);
00239    return sezi;
00240 }

static int quan ( int  val,
int *  table,
int  size 
) [static]

Definition at line 169 of file codec_g726.c.

Referenced by quantize().

00170 {
00171    int      i;
00172 
00173    for (i = 0; i < size && val >= *table; ++i, ++table)
00174       ;
00175    return (i);
00176 }

static int quantize ( int  d,
int  y,
int *  table,
int  size 
) [static]

Definition at line 285 of file codec_g726.c.

References ilog2(), and quan().

Referenced by g726_encode().

00290 {
00291    int      dqm;  /* Magnitude of 'd' */
00292    int      exp;  /* Integer part of base 2 log of 'd' */
00293    int      mant; /* Fractional part of base 2 log */
00294    int      dl;      /* Log of magnitude of 'd' */
00295    int      dln;  /* Step size scale factor normalized log */
00296    int      i;
00297 
00298    /*
00299     * LOG
00300     *
00301     * Compute base 2 log of 'd', and store in 'dl'.
00302     */
00303    dqm = abs(d);
00304    exp = ilog2(dqm);
00305    if (exp < 0)
00306       exp = 0;
00307    mant = ((dqm << 7) >> exp) & 0x7F;  /* Fractional portion. */
00308    dl = (exp << 7) | mant;
00309 
00310    /*
00311     * SUBTB
00312     *
00313     * "Divide" by step size multiplier.
00314     */
00315    dln = dl - (y >> 2);
00316 
00317    /*
00318     * QUAN
00319     *
00320     * Obtain codword i for 'd'.
00321     */
00322    i = quan(dln, table, size);
00323    if (d < 0)        /* take 1's complement of i */
00324       return ((size << 1) + 1 - i);
00325    else if (i == 0)     /* take 1's complement of 0 */
00326       return ((size << 1) + 1); /* new in 1988 */
00327    else
00328       return (i);
00329 }

static int reconstruct ( int  sign,
int  dqln,
int  y 
) [static]

Definition at line 338 of file codec_g726.c.

Referenced by bridge_p2p_rtp_write(), g726_decode(), and g726_encode().

00342 {
00343    int      dql;  /* Log of 'dq' magnitude */
00344    int      dex;  /* Integer part of log */
00345    int      dqt;
00346    int      dq;   /* Reconstructed difference signal sample */
00347 
00348    dql = dqln + (y >> 2);  /* ADDA */
00349 
00350    if (dql < 0) {
00351 #ifdef NOT_BLI
00352       return (sign) ? -1 : 1;
00353 #else
00354       return (sign) ? -0x8000 : 0;
00355 #endif
00356    } else {    /* ANTILOG */
00357       dex = (dql >> 7) & 15;
00358       dqt = 128 + (dql & 127);
00359 #ifdef NOT_BLI
00360       dq = ((dqt << 19) >> (14 - dex));
00361       return (sign) ? -dq : dq;
00362 #else
00363       dq = (dqt << 7) >> (14 - dex);
00364       return (sign) ? (dq - 0x8000) : dq;
00365 #endif
00366    }
00367 }

static int reload ( void   )  [static]

Definition at line 915 of file codec_g726.c.

References parse_config().

00916 {
00917    parse_config();
00918 
00919    return 0;
00920 }

static int step_size ( struct g726_state state_ptr  )  [static]

Definition at line 256 of file codec_g726.c.

References g726_state::ap, g726_state::yl, and g726_state::yu.

Referenced by g726_decode(), and g726_encode().

00257 {
00258    int      y;
00259    int      dif;
00260    int      al;
00261 
00262    if (state_ptr->ap >= 256)
00263       return (state_ptr->yu);
00264    else {
00265       y = state_ptr->yl >> 6;
00266       dif = state_ptr->yu - y;
00267       al = state_ptr->ap >> 2;
00268       if (dif > 0)
00269          y += (dif * al) >> 6;
00270       else if (dif < 0)
00271          y += (dif * al + 0x3F) >> 6;
00272       return (y);
00273    }
00274 }

static int unload_module ( void   )  [static]

Definition at line 922 of file codec_g726.c.

References ast_unregister_translator(), g726aal2tog726, g726aal2tolin, g726tog726aal2, g726tolin, lintog726, and lintog726aal2.

00923 {
00924    int res = 0;
00925 
00926    res |= ast_unregister_translator(&g726tolin);
00927    res |= ast_unregister_translator(&lintog726);
00928 
00929    res |= ast_unregister_translator(&g726aal2tolin);
00930    res |= ast_unregister_translator(&lintog726aal2);
00931 
00932    res |= ast_unregister_translator(&g726aal2tog726);
00933    res |= ast_unregister_translator(&g726tog726aal2);
00934 
00935    return res;
00936 }

static void update ( int  code_size,
int  y,
int  wi,
int  fi,
int  dq,
int  sr,
int  dqsez,
struct g726_state state_ptr 
) [static]

Definition at line 374 of file codec_g726.c.

References g726_state::a, g726_state::ap, g726_state::b, g726_state::dml, g726_state::dms, g726_state::dq, ilog2(), g726_state::pk, g726_state::sr, g726_state::td, g726_state::yl, and g726_state::yu.

Referenced by g726_decode(), and g726_encode().

00383 {
00384    int      cnt;
00385    int      mag;     /* Adaptive predictor, FLOAT A */
00386 #ifndef NOT_BLI
00387    int      exp;
00388 #endif
00389    int      a2p=0;      /* LIMC */
00390    int      a1ul;    /* UPA1 */
00391    int      pks1;    /* UPA2 */
00392    int      fa1;
00393    int      tr;         /* tone/transition detector */
00394    int      ylint, thr2, dqthr;
00395    int      ylfrac, thr1;
00396    int      pk0;
00397 
00398    pk0 = (dqsez < 0) ? 1 : 0; /* needed in updating predictor poles */
00399 
00400 #ifdef NOT_BLI
00401    mag = abs(dq / 0x1000); /* prediction difference magnitude */
00402 #else
00403    mag = dq & 0x7FFF;      /* prediction difference magnitude */
00404 #endif
00405    /* TRANS */
00406    ylint = state_ptr->yl >> 15;  /* exponent part of yl */
00407    ylfrac = (state_ptr->yl >> 10) & 0x1F; /* fractional part of yl */
00408    thr1 = (32 + ylfrac) << ylint;      /* threshold */
00409    thr2 = (ylint > 9) ? 31 << 10 : thr1;  /* limit thr2 to 31 << 10 */
00410    dqthr = (thr2 + (thr2 >> 1)) >> 1;  /* dqthr = 0.75 * thr2 */
00411    if (state_ptr->td == 0)    /* signal supposed voice */
00412       tr = 0;
00413    else if (mag <= dqthr)     /* supposed data, but small mag */
00414       tr = 0;        /* treated as voice */
00415    else           /* signal is data (modem) */
00416       tr = 1;
00417 
00418    /*
00419     * Quantizer scale factor adaptation.
00420     */
00421 
00422    /* FUNCTW & FILTD & DELAY */
00423    /* update non-steady state step size multiplier */
00424    state_ptr->yu = y + ((wi - y) >> 5);
00425 
00426    /* LIMB */
00427    if (state_ptr->yu < 544)   /* 544 <= yu <= 5120 */
00428       state_ptr->yu = 544;
00429    else if (state_ptr->yu > 5120)
00430       state_ptr->yu = 5120;
00431 
00432    /* FILTE & DELAY */
00433    /* update steady state step size multiplier */
00434    state_ptr->yl += state_ptr->yu + ((-state_ptr->yl) >> 6);
00435 
00436    /*
00437     * Adaptive predictor coefficients.
00438     */
00439    if (tr == 1) {       /* reset a's and b's for modem signal */
00440       state_ptr->a[0] = 0;
00441       state_ptr->a[1] = 0;
00442       state_ptr->b[0] = 0;
00443       state_ptr->b[1] = 0;
00444       state_ptr->b[2] = 0;
00445       state_ptr->b[3] = 0;
00446       state_ptr->b[4] = 0;
00447       state_ptr->b[5] = 0;
00448    } else {       /* update a's and b's */
00449       pks1 = pk0 ^ state_ptr->pk[0];      /* UPA2 */
00450 
00451       /* update predictor pole a[1] */
00452       a2p = state_ptr->a[1] - (state_ptr->a[1] >> 7);
00453       if (dqsez != 0) {
00454          fa1 = (pks1) ? state_ptr->a[0] : -state_ptr->a[0];
00455          if (fa1 < -8191)  /* a2p = function of fa1 */
00456             a2p -= 0x100;
00457          else if (fa1 > 8191)
00458             a2p += 0xFF;
00459          else
00460             a2p += fa1 >> 5;
00461 
00462          if (pk0 ^ state_ptr->pk[1])
00463             /* LIMC */
00464             if (a2p <= -12160)
00465                a2p = -12288;
00466             else if (a2p >= 12416)
00467                a2p = 12288;
00468             else
00469                a2p -= 0x80;
00470          else if (a2p <= -12416)
00471             a2p = -12288;
00472          else if (a2p >= 12160)
00473             a2p = 12288;
00474          else
00475             a2p += 0x80;
00476       }
00477 
00478       /* TRIGB & DELAY */
00479       state_ptr->a[1] = a2p;
00480 
00481       /* UPA1 */
00482       /* update predictor pole a[0] */
00483       state_ptr->a[0] -= state_ptr->a[0] >> 8;
00484       if (dqsez != 0) {
00485          if (pks1 == 0)
00486             state_ptr->a[0] += 192;
00487          else
00488             state_ptr->a[0] -= 192;
00489       }
00490       /* LIMD */
00491       a1ul = 15360 - a2p;
00492       if (state_ptr->a[0] < -a1ul)
00493          state_ptr->a[0] = -a1ul;
00494       else if (state_ptr->a[0] > a1ul)
00495          state_ptr->a[0] = a1ul;
00496 
00497       /* UPB : update predictor zeros b[6] */
00498       for (cnt = 0; cnt < 6; cnt++) {
00499          if (code_size == 5)     /* for 40Kbps G.723 */
00500             state_ptr->b[cnt] -= state_ptr->b[cnt] >> 9;
00501          else        /* for G.721 and 24Kbps G.723 */
00502             state_ptr->b[cnt] -= state_ptr->b[cnt] >> 8;
00503          if (mag)
00504          {  /* XOR */
00505             if ((dq ^ state_ptr->dq[cnt]) >= 0)
00506                state_ptr->b[cnt] += 128;
00507             else
00508                state_ptr->b[cnt] -= 128;
00509          }
00510       }
00511    }
00512 
00513    for (cnt = 5; cnt > 0; cnt--)
00514       state_ptr->dq[cnt] = state_ptr->dq[cnt-1];
00515 #ifdef NOT_BLI
00516    state_ptr->dq[0] = dq;
00517 #else
00518    /* FLOAT A : convert dq[0] to 4-bit exp, 6-bit mantissa f.p. */
00519    if (mag == 0) {
00520       state_ptr->dq[0] = (dq >= 0) ? 0x20 : 0x20 - 0x400;
00521    } else {
00522       exp = ilog2(mag) + 1;
00523       state_ptr->dq[0] = (dq >= 0) ?
00524           (exp << 6) + ((mag << 6) >> exp) :
00525           (exp << 6) + ((mag << 6) >> exp) - 0x400;
00526    }
00527 #endif
00528 
00529    state_ptr->sr[1] = state_ptr->sr[0];
00530 #ifdef NOT_BLI
00531    state_ptr->sr[0] = sr;
00532 #else
00533    /* FLOAT B : convert sr to 4-bit exp., 6-bit mantissa f.p. */
00534    if (sr == 0) {
00535       state_ptr->sr[0] = 0x20;
00536    } else if (sr > 0) {
00537       exp = ilog2(sr) + 1;
00538       state_ptr->sr[0] = (exp << 6) + ((sr << 6) >> exp);
00539    } else if (sr > -0x8000) {
00540       mag = -sr;
00541       exp = ilog2(mag) + 1;
00542       state_ptr->sr[0] =  (exp << 6) + ((mag << 6) >> exp) - 0x400;
00543    } else
00544       state_ptr->sr[0] = 0x20 - 0x400;
00545 #endif
00546 
00547    /* DELAY A */
00548    state_ptr->pk[1] = state_ptr->pk[0];
00549    state_ptr->pk[0] = pk0;
00550 
00551    /* TONE */
00552    if (tr == 1)      /* this sample has been treated as data */
00553       state_ptr->td = 0;   /* next one will be treated as voice */
00554    else if (a2p < -11776)  /* small sample-to-sample correlation */
00555       state_ptr->td = 1;   /* signal may be data */
00556    else           /* signal is voice */
00557       state_ptr->td = 0;
00558 
00559    /*
00560     * Adaptation speed control.
00561     */
00562    state_ptr->dms += (fi - state_ptr->dms) >> 5;      /* FILTA */
00563    state_ptr->dml += (((fi << 2) - state_ptr->dml) >> 7);   /* FILTB */
00564 
00565    if (tr == 1)
00566       state_ptr->ap = 256;
00567    else if (y < 1536)               /* SUBTC */
00568       state_ptr->ap += (0x200 - state_ptr->ap) >> 4;
00569    else if (state_ptr->td == 1)
00570       state_ptr->ap += (0x200 - state_ptr->ap) >> 4;
00571    else if (abs((state_ptr->dms << 2) - state_ptr->dml) >=
00572        (state_ptr->dml >> 3))
00573       state_ptr->ap += (0x200 - state_ptr->ap) >> 4;
00574    else
00575       state_ptr->ap += (-state_ptr->ap) >> 4;
00576 }


Variable Documentation

int _dqlntab[16] [static]

Initial value:

 {-2048, 4, 135, 213, 273, 323, 373, 425,
            425, 373, 323, 273, 213, 135, 4, -2048}

Definition at line 110 of file codec_g726.c.

int _fitab[16] [static]

Initial value:

 {0, 0, 0, 0x200, 0x200, 0x200, 0x600, 0xE00,
            0xE00, 0x600, 0x200, 0x200, 0x200, 0, 0, 0}

Definition at line 121 of file codec_g726.c.

int _witab[16] [static]

Initial value:

 {-12, 18, 41, 64, 112, 198, 355, 1122,
            1122, 355, 198, 112, 64, 41, 18, -12}

Definition at line 114 of file codec_g726.c.

struct ast_translator g726aal2tog726 [static]

Definition at line 887 of file codec_g726.c.

Referenced by load_module(), and unload_module().

struct ast_translator g726aal2tolin [static]

Definition at line 852 of file codec_g726.c.

Referenced by load_module(), and unload_module().

struct ast_translator g726tog726aal2 [static]

Definition at line 877 of file codec_g726.c.

Referenced by load_module(), and unload_module().

struct ast_translator g726tolin [static]

Definition at line 827 of file codec_g726.c.

Referenced by load_module(), parse_config(), and unload_module().

struct ast_translator lintog726 [static]

Definition at line 840 of file codec_g726.c.

Referenced by load_module(), and unload_module().

struct ast_translator lintog726aal2 [static]

Definition at line 865 of file codec_g726.c.

Referenced by load_module(), and unload_module().

int qtab_721[7] = {-124, 80, 178, 246, 300, 349, 400} [static]

Definition at line 105 of file codec_g726.c.


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