AhoLib: Fichero Fuente r1

00001 /******************************************************************
00002 *
00003 *   DECODE Version 52
00004 *
00005 ******************************************************************
00006 *
00007 *   This subroutine provides error correction and decoding
00008 *   for all LPC parameters
00009 *
00010 * INPUTS:
00011 *  ORDER  - Number of RC's
00012 *  IPITV  - Index value of pitch
00013 *  IRMS   - Coded Energy
00014 *  IRC    - Coded Reflection Coefficients
00015 *  CORRP  - Error correction:
00016 *    If FALSE, parameters are decoded directly with no delay.  If TRUE,
00017 *    most important parameter bits are protected by Hamming code and
00018 *    median smoothed.  This requires an additional frame of delay.
00019 * OUTPUTS:
00020 *  VOICE  - Half frame voicing decisions
00021 *  PITCH  - Decoded pitch
00022 *  RMS    - Energy
00023 *  RC     - Reflection coefficients
00024 *
00025 *  NOTE: Zero RC's should be done more directly, but this would affect
00026 *   coded parameter printout.
00027 */
00028 
00029 /* $$$ he cambiado los abs() por fabs() e incluido un cast a FLOAT explicito */
00030 
00031 #include "sr_lpc10.h"
00032 #include <math.h>
00033 
00034 
00035 /* last RCs bit */
00036 static INDEX bit[10] = {
00037   16, 16, 16, 16, 8, 8, 8, 8, 4, 2
00038 };
00039 
00040 
00041 INT ivtab[32] =
00042 {
00043   24960, 24960, 24960, 24960, 25480, 25480, 25483, 25480,
00044   16640, 1560, 1560, 1560, 16640, 1816, 1563,
00045   1560, 24960, 24960, 24859, 24856, 26001,
00046   25881, 25915, 25913, 1560, 1560, 7800,
00047   3640, 1561, 1561, 3643, 3641
00048 };
00049 #define F FLOAT
00050 FLOAT corth[4][8] =
00051 {
00052   {(F)32767., (F)32767., (F)32., (F)32., (F)32., (F)32., (F)16., (F)16.},
00053   {(F)10., (F)8., (F)6.4, (F)6.4, (F)11.2, (F)11.2, (F)5.6, (F)5.6},
00054   {(F)5., (F)4., (F)3.2, (F)3.2, (F)6.4, (F)6.4, (F)3.2, (F)3.2},
00055   {(F)0., (F)0., (F)0., (F)0., (F)0., (F)0., (F)0., (F)0.}
00056 };
00057 #undef F
00058 INT detau[128] =
00059 {
00060   0, 0, 0, 3, 0, 3, 3, 31, 0, 3, 3, 21, 3, 3, 29, 30,
00061   0, 3, 3, 20, 3, 25, 27, 26, 3, 23, 58, 22, 3, 24, 28, 3,
00062   0, 3, 3, 3, 3, 39, 33, 32, 3, 37, 35, 36, 3, 38, 34, 3,
00063   3, 42, 46, 44, 50, 40, 48, 3, 54, 3, 56, 3, 52, 3, 3, 1,
00064   0, 3, 3, 108, 3, 78, 100, 104, 3, 84, 92, 88, 156, 80, 96, 3,
00065   3, 74, 70, 72, 66, 76, 68, 3, 62, 3, 60, 3, 64, 3, 3, 1,
00066   3, 116, 132, 112, 148, 152, 3, 3, 140, 3, 136, 3, 144, 3, 3, 1,
00067   124, 120, 128, 3, 3, 3, 3, 1, 3, 3, 3, 1, 3, 1, 1, 1
00068 };
00069 INT zrc[ORDER] =
00070 {0, 0, 0, 0, 0, 3, 0, 2, 0, 0};
00071 INT abit[5] =
00072 {2, 4, 8, 16, 32};
00073 
00074 
00075 void decode_2400 ( INDEX itab[13], BOOL voice[2],
00076     INT * pitch, FLOAT * rms, FLOAT rc[ORDER])
00077 {
00078   INT ivoic;
00079   static INT ivp2h = 0, erate = 0, iovoic = 0;
00080   INT i, i1, i2, i4, iavgp = 60, icorf, index, iout;
00081   INT ipit, ixcor, lsb;
00082   INT errcnt;
00083   INT ethrs = 2048, ethrs1 = 128, ethrs2 = 1024, ethrs3 = 2048;
00084   INT fut = 0, pres = 1, past = 2;
00085   static short first = 1;
00086 
00087 
00088     /* Sign extend RC's */
00089     for (i = 0; i < ORDER; i++)
00090         if ((ITAB13_IRC(i) & bit[i]) != 0)
00091             ITAB13_IRC(i) -= (bit[i] << 1);
00092 
00093     /* If no error correction, do pitch and voicing then jump to decode */
00094     i4 = detau[ITAB13_IPITCH];
00095 
00096     /* Do error correction pitch and voicing */
00097     if (i4 > 4) {
00098       g_dpit[fut] = i4;
00099       ivoic = 2;
00100         iavgp = (INT)((15 * iavgp + i4 + 8) * 0.0625);  /* $$$ cast a int */
00101     }
00102     else {
00103         ivoic = i4;
00104         g_dpit[fut] = iavgp;
00105     }
00106     g_drms[fut] = ITAB13_IRMS;
00107 
00108     for (i = 0; i < ORDER; i++)
00109         g_drc[fut][i] = ITAB13_IRC(i);
00110 
00111     /* Determine index to IVTAB from V/UV decision
00112     If error rate is high then use alternate table */
00113 
00114     index = 16 * ivp2h + 4 * iovoic + ivoic + 1;
00115     i1 = ivtab[index - 1];
00116     ipit = i1 & 3;
00117     icorf = (INT)(i1 * 0.125); /* $$$ cast a int */
00118     if (erate < ethrs)
00119         icorf = (INT)(icorf * 0.015625); /* $$$ cast a int */
00120 
00121     /* Determine error rate:  4=high    1=low */
00122     ixcor = 4;
00123     if (erate < ethrs3)
00124         ixcor = 3;
00125     if (erate < ethrs2)
00126         ixcor = 2;
00127     if (erate < ethrs1)
00128         ixcor = 1;
00129 
00130     /* Voice/unvoice decision determined from bits 0 and 1 of IVTAB.
00131     voice[0] = bit1  voice[1]=bit0 */
00132     ITAB13_IVOICE = icorf & 3;
00133 
00134     /* Skip decoding on first frame because present data not yet available */
00135 
00136     if (first)
00137         first = 0;
00138     else {
00139 
00140 /*  If bit 4 of ICORF is set then correct RMS and RC(1) - RC(4).
00141    *    Determine error rate and correct errors using a Hamming 8,4 code
00142    *    during transition or unvoiced frame.  If IOUT is negative,
00143    *    more than 1 error occurred, use previous frame's parameters.    */
00144 
00145       if ((icorf & abit[3]) != 0)
00146     {
00147       errcnt = 0;
00148       lsb = g_drms[pres] & 1;
00149         index = (INT)(g_drc[pres][7] * 16 + g_drms[pres] * 0.5); /* $$$ cast a int */
00150       ham84 (index, &iout, &errcnt);
00151       g_drms[pres] = g_drms[past];
00152       if (iout >= 0)
00153         g_drms[pres] = iout * 2 + lsb;
00154 
00155       for (i = 1; i <= 4; i++)
00156         {
00157           if (i == 1)
00158         i1 = (g_drc[pres][8] & 7) * 2 + (g_drc[pres][9] & 1);
00159           else
00160         i1 = g_drc[pres][8 - i] & 15;
00161 
00162           i2 = g_drc[pres][4 - i] & 31;
00163           lsb = i2 & 1;
00164                 index = (INT)(16 * i1 + i2 * 0.5);  /* $$$ cast a int */
00165                 ham84 (index, &iout, &errcnt);
00166           if (iout >= 0)
00167         {
00168           iout = iout * 2 + lsb;
00169           if ((iout & 16) == 16)
00170             iout = iout - 32;
00171         }
00172           else
00173         iout = g_drc[past][4 - i];
00174           g_drc[pres][4 - i] = iout;
00175         }
00176 
00177 /*  Determine error rate        */
00178         erate = (INT)(erate * .96875 + errcnt * 102); /* $$$ cast a int */
00179     }
00180 
00181 /*  Get unsmoothed RMS, RC's, and PITCH */
00182 
00183     ITAB13_IRMS = g_drms[pres];
00184 
00185     for (i = 0; i < ORDER; i++)
00186         ITAB13_IRC(i) = g_drc[pres][i];
00187     if (ipit == 1)
00188         g_dpit[pres] = g_dpit[past];
00189     if (ipit == 3)
00190         g_dpit[pres] = g_dpit[fut];
00191     ITAB13_IPITCH = g_dpit[pres];
00192 
00193 /*  If bit 2 of ICORF is set then smooth RMS and RC's,  */
00194 
00195       if ((icorf & abit[1]) != 0)
00196     {
00197         if (fabs ((g_drms[pres] - g_drms[fut])) >= corth[ixcor - 1][1]
00198             && fabs ((g_drms[pres] - g_drms[past])) >= corth[ixcor - 1][1])
00199         ITAB13_IRMS = median (g_drms[past], g_drms[pres], g_drms[fut]);
00200 
00201       for (i = 0; i < 6; i++)
00202         if (fabs ((g_drc[pres][i] - g_drc[fut][i])) >= corth[ixcor - 1][i + 2]
00203         && fabs ((g_drc[pres][i] - g_drc[past][i])) >= corth[ixcor - 1][i + 2])
00204           ITAB13_IRC(i) = median (g_drc[past][i], g_drc[pres][i], g_drc[fut][i]);
00205     }
00206 
00207 /*  If bit 3 of ICORF is set then smooth pitch  */
00208 
00209       if ((icorf & abit[2]) != 0)
00210     {
00211         if (fabs ((g_dpit[pres] - g_dpit[fut])) >= corth[ixcor - 1][0]
00212             && fabs ((g_dpit[pres] - g_dpit[past])) >= corth[ixcor - 1][0])
00213         ITAB13_IPITCH = median (g_dpit[past], g_dpit[pres], g_dpit[fut]);
00214     }
00215 
00216 /*  If bit 5 of ICORF is set then RC(5) - RC(10) are loaded with
00217    *  values so that after quantization bias is removed in decode
00218    *  the values will be zero.  */
00219     }               /* end if first */
00220   if ((icorf & abit[4]) != 0)
00221     for (i = 4; i < ORDER; i++)
00222       ITAB13_IRC(i) = zrc[i];
00223 
00224 
00225 
00226 /*  House keeping  - one frame delay    */
00227 
00228   iovoic = ivoic;
00229   ivp2h = ITAB13_IVOICE & 1; /* voice[1] */
00230   g_dpit[past] = g_dpit[pres];
00231   g_dpit[pres] = g_dpit[fut];
00232   g_drms[past] = g_drms[pres];
00233   g_drms[pres] = g_drms[fut];
00234 
00235   for (i = 1; i <= ORDER; i++)
00236     {
00237       g_drc[past][i - 1] = g_drc[pres][i - 1];
00238       g_drc[pres][i - 1] = g_drc[fut][i - 1];
00239     }
00240 
00241     unquant (itab,voice,pitch,rms,rc);
00242 }
r1_dec.c
