g729ev_g729_dec_lag3.c

最新的ITU-T的宽带语音编解码标准G.729.1,是对原先的G.729的最好的调整.码流输出速率可以进行自适应调整.满足未来通信要求.希望对大家有所帮助.

/* ITU-T G.729EV Optimization/Characterization Candidate                         */
/* Version:       1.0.a                                                          */
/* Revision Date: June 28, 2006                                                  */

/*
   ITU-T G.729EV Optimization/Characterization Candidate    ANSI-C Source Code
   Copyright (c) 2006 
   France Telecom, Matsushita Electric, Mindspeed, Siemens AG, ETRI, VoiceAge Corp.
   All rights reserved
*/

/*------------------------------------------------------------------------*
 *    G729EV_G729_Function Dec_lag3                                       *
 *             ~~~~~~~~                                                   *
 *   Decoding of fractional pitch lag with 1/3 resolution.                *
 * See "Enc_lag3.c" for more details about the encoding procedure.        *
 *------------------------------------------------------------------------*/

#include "stl.h"
#include "G729EV_G729_ld8k.h"


void G729EV_G729_Dec_lag3(Word16 index,     /* input : received pitch index           */
                          Word16 pit_min,   /* input : minimum pitch lag              */
                          Word16 pit_max,   /* input : maximum pitch lag              */
                          Word16 i_subfr,   /* input : subframe flag                  */
                          Word16 * T0,      /* output: integer part of pitch lag      */
                          Word16 * T0_frac  /* output: fractional part of pitch lag   */
    )
{
  Word16    i;
  Word16    T0_min, T0_max;

  IF(i_subfr == 0)              /* if 1st subframe */
  {
    IF(sub(index, 197) < 0)
    {
      /* *T0 = (index+2)/3 + 19 */

      *T0 = add(mult(add(index, 2), 10923), 19);

      /* *T0_frac = index - *T0*3 + 58 */

      i = add(add(*T0, *T0), *T0);
      *T0_frac = add(sub(index, i), 58);
    }
    ELSE
    {
      *T0 = sub(index, 112);
      *T0_frac = 0;
    }
#ifdef WMOPS
    move16();
    move16();
#endif

  }

  ELSE                          /* second subframe */
  {
    /* find T0_min and T0_max for 2nd subframe */

    T0_min = sub(*T0, 5);
    if (sub(T0_min, pit_min) < 0)
    {
      T0_min = pit_min;
#ifdef WMOPS
      move16();
#endif
    }

    T0_max = add(T0_min, 9);
    if (sub(T0_max, pit_max) > 0)
    {
      T0_max = pit_max;
#ifdef WMOPS
      move16();
#endif
      T0_min = sub(T0_max, 9);
    }

    /* i = (index+2)/3 - 1 */
    /* *T0 = i + t0_min;    */

    i = sub(mult(add(index, 2), 10923), 1);
    *T0 = add(i, T0_min);

    /* t0_frac = index - 2 - i*3; */

    i = add(add(i, i), i);
    *T0_frac = sub(sub(index, 2), i);

#ifdef WMOPS
    move16();
    move16();
#endif
  }

  return;
}