src/iLBC/iCBConstruct.c

   1
   2
   3     \f
   4
   5    /******************************************************************
   6
   7        iLBC Speech Coder ANSI-C Source Code
   8
   9        iCBConstruct.c
  10
  11        Copyright (c) 2001,
  12        Global IP Sound AB.
  13        All rights reserved.
  14
  15    ******************************************************************/
  16
  17    #include <math.h>
  18
  19    #include "iLBC_define.h"
  20    #include "gainquant.h"
  21    #include "getCBvec.h"
  22
  23    /*----------------------------------------------------------------*
  24     *  Convert the codebook indexes to make the search easier
  25     *---------------------------------------------------------------*/
  26
  27    void index_conv_enc(
  28        int *index          /* (i/o) Codebook indexes */
  29    ){
  30        int k;
  31
  32        for (k=1; k<CB_NSTAGES; k++) {
  33
  34            if ((index[k]>=108)&&(index[k]<172)) {
  35                index[k]-=64;
  36            } else if (index[k]>=236) {
  37                index[k]-=128;
  38            } else {
  39                /* ERROR */
  40            }
  41        }
  42    }
  43
  44    void index_conv_dec(
  45        int *index          /* (i/o) Codebook indexes */
  46    ){
  47        int k;
  48
  49        for (k=1; k<CB_NSTAGES; k++) {
  50
  51            if ((index[k]>=44)&&(index[k]<108)) {
  52                index[k]+=64;
  53            } else if ((index[k]>=108)&&(index[k]<128)) {
  54                index[k]+=128;
  55            } else {
  56                /* ERROR */
  57            }
  58
  59     \f
  60
  61        }
  62    }
  63
  64    /*----------------------------------------------------------------*
  65     *  Construct decoded vector from codebook and gains.
  66     *---------------------------------------------------------------*/
  67
  68    void iCBConstruct(
  69        float *decvector,   /* (o) Decoded vector */
  70        int *index,         /* (i) Codebook indices */
  71        int *gain_index,/* (i) Gain quantization indices */
  72        float *mem,         /* (i) Buffer for codevector construction */
  73        int lMem,           /* (i) Length of buffer */
  74        int veclen,         /* (i) Length of vector */
  75        int nStages         /* (i) Number of codebook stages */
  76    ){
  77        int j,k;
  78        float gain[CB_NSTAGES];
  79        float cbvec[SUBL];
  80
  81        /* gain de-quantization */
  82
  83        gain[0] = gaindequant(gain_index[0], 1.0, 32);
  84        if (nStages > 1) {
  85            gain[1] = gaindequant(gain_index[1],
  86                (float)fabs(gain[0]), 16);
  87        }
  88        if (nStages > 2) {
  89            gain[2] = gaindequant(gain_index[2],
  90                (float)fabs(gain[1]), 8);
  91        }
  92
  93        /* codebook vector construction and construction of
  94        total vector */
  95
  96        getCBvec(cbvec, mem, index[0], lMem, veclen);
  97        for (j=0;j<veclen;j++){
  98            decvector[j] = gain[0]*cbvec[j];
  99        }
 100        if (nStages > 1) {
 101            for (k=1; k<nStages; k++) {
 102                getCBvec(cbvec, mem, index[k], lMem, veclen);
 103                for (j=0;j<veclen;j++) {
 104                    decvector[j] += gain[k]*cbvec[j];
 105                }
 106            }
 107        }
 108    }
 109
 110