pwf.c

语音压缩编码中的g729p编码程序

/*
   ITU-T G.729 Annex C - Reference C code for floating point
                         implementation of G.729
                         Version 1.01 of 15.September.98
*/

/*
----------------------------------------------------------------------
                    COPYRIGHT NOTICE
----------------------------------------------------------------------
   ITU-T G.729 Annex C ANSI C source code
   Copyright (C) 1998, AT&T, France Telecom, NTT, University of
   Sherbrooke.  All rights reserved.

----------------------------------------------------------------------
*/

/*
 File : PWF.C
 Used for the floating point version of G.729 main body
 (not for G.729A)
*/

#include <math.h>
#include "typedef.h"
#include "ld8k.h"

static int     smooth = 1;
static FLOAT   lar_old[2] = {(F)0.0, (F)0.0};

/*----------------------------------------------------------------------------
* perc_var -adaptive bandwidth expansion for perceptual weighting filter
*----------------------------------------------------------------------------
*/
void perc_var(
              FLOAT *gamma1,         /* output: gamma1 value */
              FLOAT *gamma2,         /* output: gamma2 value */
              FLOAT *lsfint,         /* input : Interpolated lsf vector : 1st subframe */
              FLOAT *lsfnew,         /* input : lsf vector : 2nd subframe */
              FLOAT *r_c             /* input : Reflection coefficients */
              )
{
    FLOAT    lar[4];
    FLOAT   *lar_new;
    FLOAT   *lsf;
    FLOAT    critlar0, critlar1;
    FLOAT    d_min, temp;
    int      i, k;
    
    
    lar_new = &lar[2];
    
    /* reflection coefficients --> lar */
    for (i=0; i<2; i++)
        lar_new[i] = (FLOAT)log10( (double)( ( (F)1.0 + r_c[i]) / ((F)1.0 - r_c[i])));
    
    /* Interpolation of lar for the 1st subframe */
    for (i=0; i<2; i++) {
        lar[i] = (F)0.5 * (lar_new[i] + lar_old[i]);
        lar_old[i] = lar_new[i];
    }
    
    for (k=0; k<2; k++) {    /* LOOP : gamma2 for 1st to 2nd subframes */
        
        /* ----------------------------------------------------- */
        /*   First criterion based on the first two lars         */
        /*                                                       */
        /* smooth == 1  ==>  gamma2 is set to 0.6                    */
        /*                   gamma1 is set to 0.94               */
        /*                                                       */
        /* smooth == 0  ==>  gamma2 can vary from 0.4 to 0.7     */
        /*                   (gamma2 = -6.0 dmin + 1.0)          */
        /*                   gamma1 is set to 0.98               */
        /* ----------------------------------------------------- */
        critlar0 = lar[2*k];
        critlar1 = lar[2*k+1];
        
        if (smooth != 0) {
            if ((critlar0 <THRESH_L1 )&&(critlar1 > THRESH_H1)) smooth = 0;
        }
        else {
            if ((critlar0 > THRESH_L2)||(critlar1 < THRESH_H2)) smooth = 1;
        }
        
        if (smooth == 0) {
            /* ------------------------------------------------------ */
            /* Second criterion based on the minimum distance between */
            /* two successives lsfs                                   */
            /* ------------------------------------------------------ */
            gamma1[k] = GAMMA1_0;
            if (k == 0) lsf = lsfint;
            else lsf = lsfnew;
            d_min = lsf[1] - lsf[0];
            for (i=1; i<M-1; i++) {
                temp = lsf[i+1] - lsf[i];
                if (temp < d_min) d_min = temp;
            }
            
            gamma2[k] =  ALPHA * d_min + BETA;
            
            if (gamma2[k] > GAMMA2_0_H) gamma2[k] = GAMMA2_0_H;
            if (gamma2[k] < GAMMA2_0_L) gamma2[k] = GAMMA2_0_L;
        }
        else {
            gamma1[k] = GAMMA1_1;
            gamma2[k] = GAMMA2_1;;
        }
    }
    return;
}