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Asterisk developer's documentation


codec_g726.c

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00001 /*
00002  * Asterisk -- An open source telephony toolkit.
00003  *
00004  * Copyright (C) 1999 - 2005, Digium, Inc.
00005  *
00006  * Mark Spencer <markster@digium.com>
00007  *
00008  * Based on frompcm.c and topcm.c from the Emiliano MIPL browser/
00009  * interpreter.  See http://www.bsdtelephony.com.mx
00010  *
00011  * See http://www.asterisk.org for more information about
00012  * the Asterisk project. Please do not directly contact
00013  * any of the maintainers of this project for assistance;
00014  * the project provides a web site, mailing lists and IRC
00015  * channels for your use.
00016  *
00017  * This program is free software, distributed under the terms of
00018  * the GNU General Public License Version 2. See the LICENSE file
00019  * at the top of the source tree.
00020  */
00021 
00022 
00023 /*! \file
00024  *
00025  * \brief codec_g726.c - translate between signed linear and ITU G.726-32kbps
00026  *
00027  * \ingroup codecs
00028  */
00029 
00030 #include <fcntl.h>
00031 #include <netinet/in.h>
00032 #include <stdio.h>
00033 #include <stdlib.h>
00034 #include <string.h>
00035 #include <unistd.h>
00036 
00037 #include "asterisk.h"
00038 
00039 ASTERISK_FILE_VERSION(__FILE__, "$Revision: 7221 $")
00040 
00041 #include "asterisk/lock.h"
00042 #include "asterisk/logger.h"
00043 #include "asterisk/module.h"
00044 #include "asterisk/config.h"
00045 #include "asterisk/options.h"
00046 #include "asterisk/translate.h"
00047 #include "asterisk/channel.h"
00048 
00049 #define WANT_ASM
00050 #include "log2comp.h"
00051 
00052 /* define NOT_BLI to use a faster but not bit-level identical version */
00053 /* #define NOT_BLI */
00054 
00055 #if defined(NOT_BLI)
00056 #  if defined(_MSC_VER)
00057 typedef __int64 sint64;
00058 #  elif defined(__GNUC__)
00059 typedef long long sint64;
00060 #  else
00061 #     error 64-bit integer type is not defined for your compiler/platform
00062 #  endif
00063 #endif
00064 
00065 #define BUFFER_SIZE   8096 /* size for the translation buffers */
00066 #define BUF_SHIFT 5
00067 
00068 AST_MUTEX_DEFINE_STATIC(localuser_lock);
00069 static int localusecnt = 0;
00070 
00071 static char *tdesc = "ITU G.726-32kbps G726 Transcoder";
00072 
00073 static int useplc = 0;
00074 
00075 /* Sample frame data */
00076 
00077 #include "slin_g726_ex.h"
00078 #include "g726_slin_ex.h"
00079 
00080 /*
00081  * The following is the definition of the state structure
00082  * used by the G.721/G.723 encoder and decoder to preserve their internal
00083  * state between successive calls.  The meanings of the majority
00084  * of the state structure fields are explained in detail in the
00085  * CCITT Recommendation G.721.  The field names are essentially indentical
00086  * to variable names in the bit level description of the coding algorithm
00087  * included in this Recommendation.
00088  */
00089 struct g726_state {
00090    long yl; /* Locked or steady state step size multiplier. */
00091    int yu;     /* Unlocked or non-steady state step size multiplier. */
00092    int dms; /* Short term energy estimate. */
00093    int dml; /* Long term energy estimate. */
00094    int ap;     /* Linear weighting coefficient of 'yl' and 'yu'. */
00095 
00096    int a[2];   /* Coefficients of pole portion of prediction filter.
00097              * stored as fixed-point 1==2^14 */
00098    int b[6];   /* Coefficients of zero portion of prediction filter.
00099              * stored as fixed-point 1==2^14 */
00100    int pk[2];  /* Signs of previous two samples of a partially
00101           * reconstructed signal.
00102           */
00103    int dq[6];  /* Previous 6 samples of the quantized difference signal
00104              * stored as fixed point 1==2^12,
00105              * or in internal floating point format */
00106    int sr[2];  /* Previous 2 samples of the quantized difference signal
00107              * stored as fixed point 1==2^12,
00108              * or in internal floating point format */
00109    int td;  /* delayed tone detect, new in 1988 version */
00110 };
00111 
00112 
00113 
00114 static int qtab_721[7] = {-124, 80, 178, 246, 300, 349, 400};
00115 /*
00116  * Maps G.721 code word to reconstructed scale factor normalized log
00117  * magnitude values.
00118  */
00119 static int _dqlntab[16] = {-2048, 4, 135, 213, 273, 323, 373, 425,
00120             425, 373, 323, 273, 213, 135, 4, -2048};
00121 
00122 /* Maps G.721 code word to log of scale factor multiplier. */
00123 static int _witab[16] = {-12, 18, 41, 64, 112, 198, 355, 1122,
00124             1122, 355, 198, 112, 64, 41, 18, -12};
00125 /*
00126  * Maps G.721 code words to a set of values whose long and short
00127  * term averages are computed and then compared to give an indication
00128  * how stationary (steady state) the signal is.
00129  */
00130 static int _fitab[16] = {0, 0, 0, 0x200, 0x200, 0x200, 0x600, 0xE00,
00131             0xE00, 0x600, 0x200, 0x200, 0x200, 0, 0, 0};
00132 
00133 /* Deprecated
00134 static int power2[15] = {1, 2, 4, 8, 0x10, 0x20, 0x40, 0x80,
00135          0x100, 0x200, 0x400, 0x800, 0x1000, 0x2000, 0x4000};
00136 */
00137 
00138 /*
00139  * g72x_init_state()
00140  *
00141  * This routine initializes and/or resets the g726_state structure
00142  * pointed to by 'state_ptr'.
00143  * All the initial state values are specified in the CCITT G.721 document.
00144  */
00145 static void g726_init_state(struct g726_state *state_ptr)
00146 {
00147    int      cnta;
00148 
00149    state_ptr->yl = 34816;
00150    state_ptr->yu = 544;
00151    state_ptr->dms = 0;
00152    state_ptr->dml = 0;
00153    state_ptr->ap = 0;
00154    for (cnta = 0; cnta < 2; cnta++)
00155    {
00156       state_ptr->a[cnta] = 0;
00157       state_ptr->pk[cnta] = 0;
00158 #ifdef NOT_BLI
00159       state_ptr->sr[cnta] = 1;
00160 #else
00161       state_ptr->sr[cnta] = 32;
00162 #endif
00163    }
00164    for (cnta = 0; cnta < 6; cnta++)
00165    {
00166       state_ptr->b[cnta] = 0;
00167 #ifdef NOT_BLI
00168       state_ptr->dq[cnta] = 1;
00169 #else
00170       state_ptr->dq[cnta] = 32;
00171 #endif
00172    }
00173    state_ptr->td = 0;
00174 }
00175 
00176 /*
00177  * quan()
00178  *
00179  * quantizes the input val against the table of integers.
00180  * It returns i if table[i - 1] <= val < table[i].
00181  *
00182  * Using linear search for simple coding.
00183  */
00184 static int quan(int val, int *table, int size)
00185 {
00186    int      i;
00187 
00188    for (i = 0; i < size && val >= *table; ++i, ++table)
00189       ;
00190    return (i);
00191 }
00192 
00193 #ifdef NOT_BLI /* faster non-identical version */
00194 
00195 /*
00196  * predictor_zero()
00197  *
00198  * computes the estimated signal from 6-zero predictor.
00199  *
00200  */
00201 static int predictor_zero(struct g726_state *state_ptr)
00202 {  /* divide by 2 is necessary here to handle negative numbers correctly */
00203    int i;
00204    sint64 sezi;
00205    for (sezi = 0, i = 0; i < 6; i++)         /* ACCUM */
00206       sezi += (sint64)state_ptr->b[i] * state_ptr->dq[i];
00207    return (int)(sezi >> 13) / 2 /* 2^14 */;
00208 }
00209 
00210 /*
00211  * predictor_pole()
00212  *
00213  * computes the estimated signal from 2-pole predictor.
00214  *
00215  */
00216 static int predictor_pole(struct g726_state *state_ptr)
00217 {  /* divide by 2 is necessary here to handle negative numbers correctly */
00218    return (int)(((sint64)state_ptr->a[1] * state_ptr->sr[1] +
00219                  (sint64)state_ptr->a[0] * state_ptr->sr[0]) >> 13) / 2 /* 2^14 */;
00220 }
00221 
00222 #else /* NOT_BLI - identical version */
00223 /*
00224  * fmult()
00225  *
00226  * returns the integer product of the fixed-point number "an" (1==2^12) and
00227  * "floating point" representation (4-bit exponent, 6-bit mantessa) "srn".
00228  */
00229 static int fmult(int an, int srn)
00230 {
00231    int      anmag, anexp, anmant;
00232    int      wanexp, wanmant;
00233    int      retval;
00234 
00235    anmag = (an > 0) ? an : ((-an) & 0x1FFF);
00236    anexp = ilog2(anmag) - 5;
00237    anmant = (anmag == 0) ? 32 :
00238        (anexp >= 0) ? anmag >> anexp : anmag << -anexp;
00239    wanexp = anexp + ((srn >> 6) & 0xF) - 13;
00240 
00241    wanmant = (anmant * (srn & 077) + 0x30) >> 4;
00242    retval = (wanexp >= 0) ? ((wanmant << wanexp) & 0x7FFF) :
00243        (wanmant >> -wanexp);
00244 
00245    return (((an ^ srn) < 0) ? -retval : retval);
00246 }
00247 
00248 static int predictor_zero(struct g726_state *state_ptr)
00249 {
00250    int      i;
00251    int      sezi;
00252    for (sezi = 0, i = 0; i < 6; i++)         /* ACCUM */
00253       sezi += fmult(state_ptr->b[i] >> 2, state_ptr->dq[i]);
00254    return sezi;
00255 }
00256 
00257 static int predictor_pole(struct g726_state *state_ptr)
00258 {
00259    return (fmult(state_ptr->a[1] >> 2, state_ptr->sr[1]) +
00260          fmult(state_ptr->a[0] >> 2, state_ptr->sr[0]));
00261 }
00262 
00263 #endif /* NOT_BLI */
00264 
00265 /*
00266  * step_size()
00267  *
00268  * computes the quantization step size of the adaptive quantizer.
00269  *
00270  */
00271 static int step_size(struct g726_state *state_ptr)
00272 {
00273    int      y;
00274    int      dif;
00275    int      al;
00276 
00277    if (state_ptr->ap >= 256)
00278       return (state_ptr->yu);
00279    else {
00280       y = state_ptr->yl >> 6;
00281       dif = state_ptr->yu - y;
00282       al = state_ptr->ap >> 2;
00283       if (dif > 0)
00284          y += (dif * al) >> 6;
00285       else if (dif < 0)
00286          y += (dif * al + 0x3F) >> 6;
00287       return (y);
00288    }
00289 }
00290 
00291 /*
00292  * quantize()
00293  *
00294  * Given a raw sample, 'd', of the difference signal and a
00295  * quantization step size scale factor, 'y', this routine returns the
00296  * ADPCM codeword to which that sample gets quantized.  The step
00297  * size scale factor division operation is done in the log base 2 domain
00298  * as a subtraction.
00299  */
00300 static int quantize(
00301    int      d, /* Raw difference signal sample */
00302    int      y, /* Step size multiplier */
00303    int      *table,  /* quantization table */
00304    int      size) /* table size of integers */
00305 {
00306    int      dqm;  /* Magnitude of 'd' */
00307    int      exp;  /* Integer part of base 2 log of 'd' */
00308    int      mant; /* Fractional part of base 2 log */
00309    int      dl;      /* Log of magnitude of 'd' */
00310    int      dln;  /* Step size scale factor normalized log */
00311    int      i;
00312 
00313    /*
00314     * LOG
00315     *
00316     * Compute base 2 log of 'd', and store in 'dl'.
00317     */
00318    dqm = abs(d);
00319    exp = ilog2(dqm);
00320    if (exp < 0)
00321       exp = 0;
00322    mant = ((dqm << 7) >> exp) & 0x7F;  /* Fractional portion. */
00323    dl = (exp << 7) | mant;
00324 
00325    /*
00326     * SUBTB
00327     *
00328     * "Divide" by step size multiplier.
00329     */
00330    dln = dl - (y >> 2);
00331 
00332    /*
00333     * QUAN
00334     *
00335     * Obtain codword i for 'd'.
00336     */
00337    i = quan(dln, table, size);
00338    if (d < 0)        /* take 1's complement of i */
00339       return ((size << 1) + 1 - i);
00340    else if (i == 0)     /* take 1's complement of 0 */
00341       return ((size << 1) + 1); /* new in 1988 */
00342    else
00343       return (i);
00344 }
00345 
00346 /*
00347  * reconstruct()
00348  *
00349  * Returns reconstructed difference signal 'dq' obtained from
00350  * codeword 'i' and quantization step size scale factor 'y'.
00351  * Multiplication is performed in log base 2 domain as addition.
00352  */
00353 static int reconstruct(
00354    int      sign, /* 0 for non-negative value */
00355    int      dqln, /* G.72x codeword */
00356    int      y) /* Step size multiplier */
00357 {
00358    int      dql;  /* Log of 'dq' magnitude */
00359    int      dex;  /* Integer part of log */
00360    int      dqt;
00361    int      dq;   /* Reconstructed difference signal sample */
00362 
00363    dql = dqln + (y >> 2);  /* ADDA */
00364 
00365    if (dql < 0) {
00366 #ifdef NOT_BLI
00367       return (sign) ? -1 : 1;
00368 #else
00369       return (sign) ? -0x8000 : 0;
00370 #endif
00371    } else {    /* ANTILOG */
00372       dex = (dql >> 7) & 15;
00373       dqt = 128 + (dql & 127);
00374 #ifdef NOT_BLI
00375       dq = ((dqt << 19) >> (14 - dex));
00376       return (sign) ? -dq : dq;
00377 #else
00378       dq = (dqt << 7) >> (14 - dex);
00379       return (sign) ? (dq - 0x8000) : dq;
00380 #endif
00381    }
00382 }
00383 
00384 /*
00385  * update()
00386  *
00387  * updates the state variables for each output code
00388  */
00389 static void update(
00390    int      code_size,  /* distinguish 723_40 with others */
00391    int      y,    /* quantizer step size */
00392    int      wi,      /* scale factor multiplier */
00393    int      fi,      /* for long/short term energies */
00394    int      dq,      /* quantized prediction difference */
00395    int      sr,      /* reconstructed signal */
00396    int      dqsez,      /* difference from 2-pole predictor */
00397    struct g726_state *state_ptr) /* coder state pointer */
00398 {
00399    int      cnt;
00400    int      mag;     /* Adaptive predictor, FLOAT A */
00401 #ifndef NOT_BLI
00402    int      exp;
00403 #endif
00404    int      a2p=0;      /* LIMC */
00405    int      a1ul;    /* UPA1 */
00406    int      pks1;    /* UPA2 */
00407    int      fa1;
00408    int      tr;         /* tone/transition detector */
00409    int      ylint, thr2, dqthr;
00410    int      ylfrac, thr1;
00411    int      pk0;
00412 
00413    pk0 = (dqsez < 0) ? 1 : 0; /* needed in updating predictor poles */
00414 
00415 #ifdef NOT_BLI
00416    mag = abs(dq / 0x1000); /* prediction difference magnitude */
00417 #else
00418    mag = dq & 0x7FFF;      /* prediction difference magnitude */
00419 #endif
00420    /* TRANS */
00421    ylint = state_ptr->yl >> 15;  /* exponent part of yl */
00422    ylfrac = (state_ptr->yl >> 10) & 0x1F; /* fractional part of yl */
00423    thr1 = (32 + ylfrac) << ylint;      /* threshold */
00424    thr2 = (ylint > 9) ? 31 << 10 : thr1;  /* limit thr2 to 31 << 10 */
00425    dqthr = (thr2 + (thr2 >> 1)) >> 1;  /* dqthr = 0.75 * thr2 */
00426    if (state_ptr->td == 0)    /* signal supposed voice */
00427       tr = 0;
00428    else if (mag <= dqthr)     /* supposed data, but small mag */
00429       tr = 0;        /* treated as voice */
00430    else           /* signal is data (modem) */
00431       tr = 1;
00432 
00433    /*
00434     * Quantizer scale factor adaptation.
00435     */
00436 
00437    /* FUNCTW & FILTD & DELAY */
00438    /* update non-steady state step size multiplier */
00439    state_ptr->yu = y + ((wi - y) >> 5);
00440 
00441    /* LIMB */
00442    if (state_ptr->yu < 544)   /* 544 <= yu <= 5120 */
00443       state_ptr->yu = 544;
00444    else if (state_ptr->yu > 5120)
00445       state_ptr->yu = 5120;
00446 
00447    /* FILTE & DELAY */
00448    /* update steady state step size multiplier */
00449    state_ptr->yl += state_ptr->yu + ((-state_ptr->yl) >> 6);
00450 
00451    /*
00452     * Adaptive predictor coefficients.
00453     */
00454    if (tr == 1) {       /* reset a's and b's for modem signal */
00455       state_ptr->a[0] = 0;
00456       state_ptr->a[1] = 0;
00457       state_ptr->b[0] = 0;
00458       state_ptr->b[1] = 0;
00459       state_ptr->b[2] = 0;
00460       state_ptr->b[3] = 0;
00461       state_ptr->b[4] = 0;
00462       state_ptr->b[5] = 0;
00463    } else {       /* update a's and b's */
00464       pks1 = pk0 ^ state_ptr->pk[0];      /* UPA2 */
00465 
00466       /* update predictor pole a[1] */
00467       a2p = state_ptr->a[1] - (state_ptr->a[1] >> 7);
00468       if (dqsez != 0) {
00469          fa1 = (pks1) ? state_ptr->a[0] : -state_ptr->a[0];
00470          if (fa1 < -8191)  /* a2p = function of fa1 */
00471             a2p -= 0x100;
00472          else if (fa1 > 8191)
00473             a2p += 0xFF;
00474          else
00475             a2p += fa1 >> 5;
00476 
00477          if (pk0 ^ state_ptr->pk[1])
00478             /* LIMC */
00479             if (a2p <= -12160)
00480                a2p = -12288;
00481             else if (a2p >= 12416)
00482                a2p = 12288;
00483             else
00484                a2p -= 0x80;
00485          else if (a2p <= -12416)
00486             a2p = -12288;
00487          else if (a2p >= 12160)
00488             a2p = 12288;
00489          else
00490             a2p += 0x80;
00491       }
00492 
00493       /* TRIGB & DELAY */
00494       state_ptr->a[1] = a2p;
00495 
00496       /* UPA1 */
00497       /* update predictor pole a[0] */
00498       state_ptr->a[0] -= state_ptr->a[0] >> 8;
00499       if (dqsez != 0) {
00500          if (pks1 == 0)
00501             state_ptr->a[0] += 192;
00502          else
00503             state_ptr->a[0] -= 192;
00504       }
00505       /* LIMD */
00506       a1ul = 15360 - a2p;
00507       if (state_ptr->a[0] < -a1ul)
00508          state_ptr->a[0] = -a1ul;
00509       else if (state_ptr->a[0] > a1ul)
00510          state_ptr->a[0] = a1ul;
00511 
00512       /* UPB : update predictor zeros b[6] */
00513       for (cnt = 0; cnt < 6; cnt++) {
00514          if (code_size == 5)     /* for 40Kbps G.723 */
00515             state_ptr->b[cnt] -= state_ptr->b[cnt] >> 9;
00516          else        /* for G.721 and 24Kbps G.723 */
00517             state_ptr->b[cnt] -= state_ptr->b[cnt] >> 8;
00518          if (mag)
00519          {  /* XOR */
00520             if ((dq ^ state_ptr->dq[cnt]) >= 0)
00521                state_ptr->b[cnt] += 128;
00522             else
00523                state_ptr->b[cnt] -= 128;
00524          }
00525       }
00526    }
00527 
00528    for (cnt = 5; cnt > 0; cnt--)
00529       state_ptr->dq[cnt] = state_ptr->dq[cnt-1];
00530 #ifdef NOT_BLI
00531    state_ptr->dq[0] = dq;
00532 #else
00533    /* FLOAT A : convert dq[0] to 4-bit exp, 6-bit mantissa f.p. */
00534    if (mag == 0) {
00535       state_ptr->dq[0] = (dq >= 0) ? 0x20 : 0x20 - 0x400;
00536    } else {
00537       exp = ilog2(mag) + 1;
00538       state_ptr->dq[0] = (dq >= 0) ?
00539           (exp << 6) + ((mag << 6) >> exp) :
00540           (exp << 6) + ((mag << 6) >> exp) - 0x400;
00541    }
00542 #endif
00543 
00544    state_ptr->sr[1] = state_ptr->sr[0];
00545 #ifdef NOT_BLI
00546    state_ptr->sr[0] = sr;
00547 #else
00548    /* FLOAT B : convert sr to 4-bit exp., 6-bit mantissa f.p. */
00549    if (sr == 0) {
00550       state_ptr->sr[0] = 0x20;
00551    } else if (sr > 0) {
00552       exp = ilog2(sr) + 1;
00553       state_ptr->sr[0] = (exp << 6) + ((sr << 6) >> exp);
00554    } else if (sr > -0x8000) {
00555       mag = -sr;
00556       exp = ilog2(mag) + 1;
00557       state_ptr->sr[0] =  (exp << 6) + ((mag << 6) >> exp) - 0x400;
00558    } else
00559       state_ptr->sr[0] = 0x20 - 0x400;
00560 #endif
00561 
00562    /* DELAY A */
00563    state_ptr->pk[1] = state_ptr->pk[0];
00564    state_ptr->pk[0] = pk0;
00565 
00566    /* TONE */
00567    if (tr == 1)      /* this sample has been treated as data */
00568       state_ptr->td = 0;   /* next one will be treated as voice */
00569    else if (a2p < -11776)  /* small sample-to-sample correlation */
00570       state_ptr->td = 1;   /* signal may be data */
00571    else           /* signal is voice */
00572       state_ptr->td = 0;
00573 
00574    /*
00575     * Adaptation speed control.
00576     */
00577    state_ptr->dms += (fi - state_ptr->dms) >> 5;      /* FILTA */
00578    state_ptr->dml += (((fi << 2) - state_ptr->dml) >> 7);   /* FILTB */
00579 
00580    if (tr == 1)
00581       state_ptr->ap = 256;
00582    else if (y < 1536)               /* SUBTC */
00583       state_ptr->ap += (0x200 - state_ptr->ap) >> 4;
00584    else if (state_ptr->td == 1)
00585       state_ptr->ap += (0x200 - state_ptr->ap) >> 4;
00586    else if (abs((state_ptr->dms << 2) - state_ptr->dml) >=
00587        (state_ptr->dml >> 3))
00588       state_ptr->ap += (0x200 - state_ptr->ap) >> 4;
00589    else
00590       state_ptr->ap += (-state_ptr->ap) >> 4;
00591 }
00592 
00593 /*
00594  * g726_decode()
00595  *
00596  * Description:
00597  *
00598  * Decodes a 4-bit code of G.726-32 encoded data of i and
00599  * returns the resulting linear PCM, A-law or u-law value.
00600  * return -1 for unknown out_coding value.
00601  */
00602 static int g726_decode(int i, struct g726_state *state_ptr)
00603 {
00604    int      sezi, sez, se; /* ACCUM */
00605    int      y;       /* MIX */
00606    int      sr;         /* ADDB */
00607    int      dq;
00608    int      dqsez;
00609 
00610    i &= 0x0f;        /* mask to get proper bits */
00611 #ifdef NOT_BLI
00612    sezi = predictor_zero(state_ptr);
00613    sez = sezi;
00614    se = sezi + predictor_pole(state_ptr); /* estimated signal */
00615 #else
00616    sezi = predictor_zero(state_ptr);
00617    sez = sezi >> 1;
00618    se = (sezi + predictor_pole(state_ptr)) >> 1;   /* estimated signal */
00619 #endif
00620 
00621    y = step_size(state_ptr);  /* dynamic quantizer step size */
00622 
00623    dq = reconstruct(i & 8, _dqlntab[i], y); /* quantized diff. */
00624 
00625 #ifdef NOT_BLI
00626    sr = se + dq;           /* reconst. signal */
00627    dqsez = dq + sez;       /* pole prediction diff. */
00628 #else
00629    sr = (dq < 0) ? se - (dq & 0x3FFF) : se + dq;   /* reconst. signal */
00630    dqsez = sr - se + sez;     /* pole prediction diff. */
00631 #endif
00632 
00633    update(4, y, _witab[i] << 5, _fitab[i], dq, sr, dqsez, state_ptr);
00634 
00635 #ifdef NOT_BLI
00636    return (sr >> 10);   /* sr was 26-bit dynamic range */
00637 #else
00638    return (sr << 2); /* sr was 14-bit dynamic range */
00639 #endif
00640 }
00641 
00642 /*
00643  * g726_encode()
00644  *
00645  * Encodes the input vale of linear PCM, A-law or u-law data sl and returns
00646  * the resulting code. -1 is returned for unknown input coding value.
00647  */
00648 static int g726_encode(int sl, struct g726_state *state_ptr)
00649 {
00650    int      sezi, se, sez;    /* ACCUM */
00651    int      d;       /* SUBTA */
00652    int      sr;         /* ADDB */
00653    int      y;       /* MIX */
00654    int      dqsez;         /* ADDC */
00655    int      dq, i;
00656 
00657 #ifdef NOT_BLI
00658    sl <<= 10;        /* 26-bit dynamic range */
00659 
00660    sezi = predictor_zero(state_ptr);
00661    sez = sezi;
00662    se = sezi + predictor_pole(state_ptr); /* estimated signal */
00663 #else
00664    sl >>= 2;         /* 14-bit dynamic range */
00665 
00666    sezi = predictor_zero(state_ptr);
00667    sez = sezi >> 1;
00668    se = (sezi + predictor_pole(state_ptr)) >> 1;   /* estimated signal */
00669 #endif
00670 
00671    d = sl - se;            /* estimation difference */
00672 
00673    /* quantize the prediction difference */
00674    y = step_size(state_ptr);     /* quantizer step size */
00675 #ifdef NOT_BLI
00676    d /= 0x1000;
00677 #endif
00678    i = quantize(d, y, qtab_721, 7); /* i = G726 code */
00679 
00680    dq = reconstruct(i & 8, _dqlntab[i], y);  /* quantized est diff */
00681 
00682 #ifdef NOT_BLI
00683    sr = se + dq;           /* reconst. signal */
00684    dqsez = dq + sez;       /* pole prediction diff. */
00685 #else
00686    sr = (dq < 0) ? se - (dq & 0x3FFF) : se + dq;   /* reconst. signal */
00687    dqsez = sr - se + sez;        /* pole prediction diff. */
00688 #endif
00689 
00690    update(4, y, _witab[i] << 5, _fitab[i], dq, sr, dqsez, state_ptr);
00691 
00692    return (i);
00693 }
00694 
00695 /*
00696  * Private workspace for translating signed linear signals to G726.
00697  */
00698 
00699 struct g726_encoder_pvt
00700 {
00701   struct ast_frame f;
00702   char offset[AST_FRIENDLY_OFFSET];   /* Space to build offset */
00703   unsigned char outbuf[BUFFER_SIZE];  /* Encoded G726, two nibbles to a word */
00704   unsigned char next_flag;
00705   struct g726_state g726;
00706   int tail;
00707 };
00708 
00709 /*
00710  * Private workspace for translating G726 signals to signed linear.
00711  */
00712 
00713 struct g726_decoder_pvt
00714 {
00715   struct ast_frame f;
00716   char offset[AST_FRIENDLY_OFFSET]; /* Space to build offset */
00717   short outbuf[BUFFER_SIZE];  /* Decoded signed linear values */
00718   struct g726_state g726;
00719   int tail;
00720   plc_state_t plc;
00721 };
00722 
00723 /*
00724  * G726ToLin_New
00725  *  Create a new instance of g726_decoder_pvt.
00726  *
00727  * Results:
00728  *  Returns a pointer to the new instance.
00729  *
00730  * Side effects:
00731  *  None.
00732  */
00733 
00734 static struct ast_translator_pvt *
00735 g726tolin_new (void)
00736 {
00737   struct g726_decoder_pvt *tmp;
00738   tmp = malloc (sizeof (struct g726_decoder_pvt));
00739   if (tmp)
00740     {
00741      memset(tmp, 0, sizeof(*tmp));
00742       tmp->tail = 0;
00743       plc_init(&tmp->plc);
00744       localusecnt++;
00745      g726_init_state(&tmp->g726);
00746       ast_update_use_count ();
00747     }
00748   return (struct ast_translator_pvt *) tmp;
00749 }
00750 
00751 /*
00752  * LinToG726_New
00753  *  Create a new instance of g726_encoder_pvt.
00754  *
00755  * Results:
00756  *  Returns a pointer to the new instance.
00757  *
00758  * Side effects:
00759  *  None.
00760  */
00761 
00762 static struct ast_translator_pvt *
00763 lintog726_new (void)
00764 {
00765   struct g726_encoder_pvt *tmp;
00766   tmp = malloc (sizeof (struct g726_encoder_pvt));
00767   if (tmp)
00768     {
00769      memset(tmp, 0, sizeof(*tmp));
00770       localusecnt++;
00771       tmp->tail = 0;
00772      g726_init_state(&tmp->g726);
00773       ast_update_use_count ();
00774     }
00775   return (struct ast_translator_pvt *) tmp;
00776 }
00777 
00778 /*
00779  * G726ToLin_FrameIn
00780  *  Fill an input buffer with packed 4-bit G726 values if there is room
00781  *  left.
00782  *
00783  * Results:
00784  *  Foo
00785  *
00786  * Side effects:
00787  *  tmp->tail is the number of packed values in the buffer.
00788  */
00789 
00790 static int
00791 g726tolin_framein (struct ast_translator_pvt *pvt, struct ast_frame *f)
00792 {
00793   struct g726_decoder_pvt *tmp = (struct g726_decoder_pvt *) pvt;
00794   unsigned char *b;
00795   int x;
00796 
00797   if(f->datalen == 0) { /* perform PLC with nominal framesize of 20ms/160 samples */
00798         if((tmp->tail + 160) > BUFFER_SIZE) {
00799             ast_log(LOG_WARNING, "Out of buffer space\n");
00800             return -1;
00801         }
00802         if(useplc) {
00803        plc_fillin(&tmp->plc, tmp->outbuf+tmp->tail, 160);
00804        tmp->tail += 160;
00805    }
00806         return 0;
00807   }
00808 
00809   b = f->data;
00810   for (x=0;x<f->datalen;x++) {
00811    if (tmp->tail >= BUFFER_SIZE) {
00812       ast_log(LOG_WARNING, "Out of buffer space!\n");
00813       return -1;
00814    }
00815    tmp->outbuf[tmp->tail++] = g726_decode((b[x] >> 4) & 0xf, &tmp->g726);
00816    if (tmp->tail >= BUFFER_SIZE) {
00817       ast_log(LOG_WARNING, "Out of buffer space!\n");
00818       return -1;
00819    }
00820    tmp->outbuf[tmp->tail++] = g726_decode(b[x] & 0x0f, &tmp->g726);
00821   }
00822 
00823   if(useplc) plc_rx(&tmp->plc, tmp->outbuf+tmp->tail-f->datalen*2, f->datalen*2);
00824 
00825   return 0;
00826 }
00827 
00828 /*
00829  * G726ToLin_FrameOut
00830  *  Convert 4-bit G726 encoded signals to 16-bit signed linear.
00831  *
00832  * Results:
00833  *  Converted signals are placed in tmp->f.data, tmp->f.datalen
00834  *  and tmp->f.samples are calculated.
00835  *
00836  * Side effects:
00837  *  None.
00838  */
00839 
00840 static struct ast_frame *
00841 g726tolin_frameout (struct ast_translator_pvt *pvt)
00842 {
00843   struct g726_decoder_pvt *tmp = (struct g726_decoder_pvt *) pvt;
00844 
00845   if (!tmp->tail)
00846     return NULL;
00847 
00848   tmp->f.frametype = AST_FRAME_VOICE;
00849   tmp->f.subclass = AST_FORMAT_SLINEAR;
00850   tmp->f.datalen = tmp->tail * 2;
00851   tmp->f.samples = tmp->tail;
00852   tmp->f.mallocd = 0;
00853   tmp->f.offset = AST_FRIENDLY_OFFSET;
00854   tmp->f.src = __PRETTY_FUNCTION__;
00855   tmp->f.data = tmp->outbuf;
00856   tmp->tail = 0;
00857   return &tmp->f;
00858 }
00859 
00860 /*
00861  * LinToG726_FrameIn
00862  *  Fill an input buffer with 16-bit signed linear PCM values.
00863  *
00864  * Results:
00865  *  None.
00866  *
00867  * Side effects:
00868  *  tmp->tail is number of signal values in the input buffer.
00869  */
00870 
00871 static int
00872 lintog726_framein (struct ast_translator_pvt *pvt, struct ast_frame *f)
00873 {
00874   struct g726_encoder_pvt *tmp = (struct g726_encoder_pvt *) pvt;
00875   short *s = f->data;
00876   int samples = f->datalen / 2;
00877   int x;
00878   for (x=0;x<samples;x++) {
00879    if (tmp->next_flag & 0x80) {
00880       if (tmp->tail >= BUFFER_SIZE) {
00881          ast_log(LOG_WARNING, "Out of buffer space\n");
00882          return -1;
00883       }
00884       tmp->outbuf[tmp->tail++] = ((tmp->next_flag & 0xf)<< 4) | g726_encode(s[x], &tmp->g726);
00885       tmp->next_flag = 0;
00886    } else {
00887       tmp->next_flag = 0x80 | g726_encode(s[x], &tmp->g726);
00888    }
00889   }
00890   return 0;
00891 }
00892 
00893 /*
00894  * LinToG726_FrameOut
00895  *  Convert a buffer of raw 16-bit signed linear PCM to a buffer
00896  *  of 4-bit G726 packed two to a byte (Big Endian).
00897  *
00898  * Results:
00899  *  Foo
00900  *
00901  * Side effects:
00902  *  Leftover inbuf data gets packed, tail gets updated.
00903  */
00904 
00905 static struct ast_frame *
00906 lintog726_frameout (struct ast_translator_pvt *pvt)
00907 {
00908   struct g726_encoder_pvt *tmp = (struct g726_encoder_pvt *) pvt;
00909   
00910   if (!tmp->tail)
00911    return NULL;
00912   tmp->f.frametype = AST_FRAME_VOICE;
00913   tmp->f.subclass = AST_FORMAT_G726;
00914   tmp->f.samples = tmp->tail * 2;
00915   tmp->f.mallocd = 0;
00916   tmp->f.offset = AST_FRIENDLY_OFFSET;
00917   tmp->f.src = __PRETTY_FUNCTION__;
00918   tmp->f.data = tmp->outbuf;
00919   tmp->f.datalen = tmp->tail;
00920 
00921   tmp->tail = 0;
00922   return &tmp->f;
00923 }
00924 
00925 
00926 /*
00927  * G726ToLin_Sample
00928  */
00929 
00930 static struct ast_frame *
00931 g726tolin_sample (void)
00932 {
00933   static struct ast_frame f;
00934   f.frametype = AST_FRAME_VOICE;
00935   f.subclass = AST_FORMAT_G726;
00936   f.datalen = sizeof (g726_slin_ex);
00937   f.samples = sizeof(g726_slin_ex) * 2;
00938   f.mallocd = 0;
00939   f.offset = 0;
00940   f.src = __PRETTY_FUNCTION__;
00941   f.data = g726_slin_ex;
00942   return &f;
00943 }
00944 
00945 /*
00946  * LinToG726_Sample
00947  */
00948 
00949 static struct ast_frame *
00950 lintog726_sample (void)
00951 {
00952   static struct ast_frame f;
00953   f.frametype = AST_FRAME_VOICE;
00954   f.subclass = AST_FORMAT_SLINEAR;
00955   f.datalen = sizeof (slin_g726_ex);
00956   /* Assume 8000 Hz */
00957   f.samples = sizeof (slin_g726_ex) / 2;
00958   f.mallocd = 0;
00959   f.offset = 0;
00960   f.src = __PRETTY_FUNCTION__;
00961   f.data = slin_g726_ex;
00962   return &f;
00963 }
00964 
00965 /*
00966  * G726_Destroy
00967  *  Destroys a private workspace.
00968  *
00969  * Results:
00970  *  It's gone!
00971  *
00972  * Side effects:
00973  *  None.
00974  */
00975 
00976 static void
00977 g726_destroy (struct ast_translator_pvt *pvt)
00978 {
00979   free (pvt);
00980   localusecnt--;
00981   ast_update_use_count ();
00982 }
00983 
00984 /*
00985  * The complete translator for G726ToLin.
00986  */
00987 
00988 static struct ast_translator g726tolin = {
00989   "g726tolin",
00990   AST_FORMAT_G726,
00991   AST_FORMAT_SLINEAR,
00992   g726tolin_new,
00993   g726tolin_framein,
00994   g726tolin_frameout,
00995   g726_destroy,
00996   /* NULL */
00997   g726tolin_sample
00998 };
00999 
01000 /*
01001  * The complete translator for LinToG726.
01002  */
01003 
01004 static struct ast_translator lintog726 = {
01005   "lintog726",
01006   AST_FORMAT_SLINEAR,
01007   AST_FORMAT_G726,
01008   lintog726_new,
01009   lintog726_framein,
01010   lintog726_frameout,
01011   g726_destroy,
01012   /* NULL */
01013   lintog726_sample
01014 };
01015 
01016 static void 
01017 parse_config(void)
01018 {
01019   struct ast_config *cfg;
01020   struct ast_variable *var;
01021   if ((cfg = ast_config_load("codecs.conf"))) {
01022     if ((var = ast_variable_browse(cfg, "plc"))) {
01023       while (var) {
01024        if (!strcasecmp(var->name, "genericplc")) {
01025          useplc = ast_true(var->value) ? 1 : 0;
01026          if (option_verbose > 2)
01027            ast_verbose(VERBOSE_PREFIX_3 "codec_g726: %susing generic PLC\n", useplc ? "" : "not ");
01028        }
01029        var = var->next;
01030       }
01031     }
01032     ast_config_destroy(cfg);
01033   }
01034 }
01035 
01036 int
01037 reload(void)
01038 {
01039   parse_config();
01040   return 0;
01041 }
01042 
01043 int
01044 unload_module (void)
01045 {
01046   int res;
01047   ast_mutex_lock (&localuser_lock);
01048   res = ast_unregister_translator (&lintog726);
01049   if (!res)
01050     res = ast_unregister_translator (&g726tolin);
01051   if (localusecnt)
01052     res = -1;
01053   ast_mutex_unlock (&localuser_lock);
01054   return res;
01055 }
01056 
01057 int
01058 load_module (void)
01059 {
01060   int res;
01061   parse_config();
01062   res = ast_register_translator (&g726tolin);
01063   if (!res)
01064     res = ast_register_translator (&lintog726);
01065   else
01066     ast_unregister_translator (&g726tolin);
01067   return res;
01068 }
01069 
01070 /*
01071  * Return a description of this module.
01072  */
01073 
01074 char *
01075 description (void)
01076 {
01077   return tdesc;
01078 }
01079 
01080 int
01081 usecount (void)
01082 {
01083   int res;
01084   STANDARD_USECOUNT (res);
01085   return res;
01086 }
01087 
01088 char *
01089 key ()
01090 {
01091   return ASTERISK_GPL_KEY;
01092 }

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