cor_func.c

g729a 语音编码,再linux c 环境下实现,有非常的好的移植性,通话质量好

/*
   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 : COR_FUNC.C
 Used for the floating point version of both
 G.729 main body and G.729A
*/

/* Functions corr_xy2() and cor_h_x()   */

#include "typedef.h"
#include "version.h"
#ifdef VER_G729A
 #include "ld8a.h"
#else
 #include "ld8k.h"
#endif

/*----------------------------------------------------------------------------
 * corr_xy2 - compute the correlation products needed for gain computation
 *----------------------------------------------------------------------------
 */
void corr_xy2(
 FLOAT xn[],            /* input : target vector x[0:l_subfr] */
 FLOAT y1[],            /* input : filtered adaptive codebook vector */
 FLOAT y2[],            /* input : filtered 1st codebook innovation */
 FLOAT g_coeff[]        /* output: <y2,y2> , -2<xn,y2> , and 2<y1,y2>*/
)
{
   FLOAT y2y2, xny2, y1y2;
   int i;

   y2y2= (F)0.01;
   for (i = 0; i < L_SUBFR; i++) y2y2 += y2[i]*y2[i];
   g_coeff[2] = y2y2 ;

   xny2 = (F)0.01;
   for (i = 0; i < L_SUBFR; i++) xny2+= xn[i]*y2[i];
   g_coeff[3] = (F)-2.0* xny2;

   y1y2 = (F)0.01;
   for (i = 0; i < L_SUBFR; i++) y1y2 += y1[i]*y2[i];
   g_coeff[4] = (F)2.0* y1y2 ;

   return;

}

/*--------------------------------------------------------------------------*
 *  Function  cor_h_x()                                                     *
 *  ~~~~~~~~~~~~~~~~~~~~                                                    *
 * Compute  correlations of input response h[] with the target vector X[].  *
 *--------------------------------------------------------------------------*/

void cor_h_x(
     FLOAT h[],        /* (i) :Impulse response of filters      */
     FLOAT x[],        /* (i) :Target vector                    */
     FLOAT d[]         /* (o) :Correlations between h[] and x[] */
)
{
   int i, j;
   FLOAT  s;

   for (i = 0; i < L_SUBFR; i++)
   {
     s = (F)0.0;
     for (j = i; j <  L_SUBFR; j++)
       s += x[j] * h[j-i];
     d[i] = s;
   }

   return;
}