cod_ld8a.c

C源程序---G.729a语音代码G.729a语音代码

/*
   ITU-T G.729A Speech Coder    ANSI-C Source Code
   Version 1.1    Last modified: September 1996

   Copyright (c) 1996,
   AT&T, France Telecom, NTT, Universite de Sherbrooke
   All rights reserved.
*/

/*-----------------------------------------------------------------*
 *   Functions Coder_ld8a and Init_Coder_ld8a                      *
 *             ~~~~~~~~~~     ~~~~~~~~~~~~~~~                      *
 *                                                                 *
 *  Init_Coder_ld8a(void);                                         *
 *                                                                 *
 *   ->Initialization of variables for the coder section.          *
 *                                                                 *
 *                                                                 *
 *  Coder_ld8a(Word16 ana[]);                                      *
 *                                                                 *
 *   ->Main coder function.                                        *
 *                                                                 *
 *                                                                 *
 *  Input:                                                         *
 *                                                                 *
 *    80 speech data should have beee copy to vector new_speech[]. *
 *    This vector is global and is declared in this function.      *
 *                                                                 *
 *  Ouputs:                                                        *
 *                                                                 *
 *    ana[]      ->analysis parameters.                            *
 *                                                                 *
 *-----------------------------------------------------------------*/
#include <stdio.h>
#include <stdlib.h>

#include "typedef.h"
#include "basic_op.h"
#include "ld8a.h"

/*-----------------------------------------------------------*
 *    Coder constant parameters (defined in "ld8a.h")        *
 *-----------------------------------------------------------*
 *   L_WINDOW    : LPC analysis window size.                 *
 *   L_NEXT      : Samples of next frame needed for autocor. *
 *   L_FRAME     : Frame size.                               *
 *   L_SUBFR     : Sub-frame size.                           *
 *   M           : LPC order.                                *
 *   MP1         : LPC order+1                               *
 *   L_TOTAL     : Total size of speech buffer.              *
 *   PIT_MIN     : Minimum pitch lag.                        *
 *   PIT_MAX     : Maximum pitch lag.                        *
 *   L_INTERPOL  : Length of filter for interpolation        *
 *-----------------------------------------------------------*/

/*--------------------------------------------------------*
 *         Static memory allocation.                      *
 *--------------------------------------------------------*/

        /* Speech vector */

 static Word16 old_speech[L_TOTAL];
 static Word16 *speech, *p_window;
 Word16 *new_speech;                    /* Global variable */

        /* Weighted speech vector */

 static Word16 old_wsp[L_FRAME+PIT_MAX];
 static Word16 *wsp;

        /* Excitation vector */

 static Word16 old_exc[L_FRAME+PIT_MAX+L_INTERPOL];
 static Word16 *exc;

        /* Lsp (Line spectral pairs) */

 static Word16 lsp_old[M]={
              30000, 26000, 21000, 15000, 8000, 0, -8000,-15000,-21000,-26000};
 static Word16 lsp_old_q[M];

        /* Filter's memory */

 static Word16  mem_w0[M], mem_w[M], mem_zero[M];
 static Word16  sharp;

/*-----------------------------------------------------------------*
 *   Function  Init_Coder_ld8a                                     *
 *            ~~~~~~~~~~~~~~~                                      *
 *                                                                 *
 *  Init_Coder_ld8a(void);                                         *
 *                                                                 *
 *   ->Initialization of variables for the coder section.          *
 *       - initialize pointers to speech buffer                    *
 *       - initialize static  pointers                             *
 *       - set static vectors to zero                              *
 *                                                                 *
 *-----------------------------------------------------------------*/

void Init_Coder_ld8a(void)
{

  /*----------------------------------------------------------------------*
  *      Initialize pointers to speech vector.                            *
  *                                                                       *
  *                                                                       *
  *   |--------------------|-------------|-------------|------------|     *
  *     previous speech           sf1           sf2         L_NEXT        *
  *                                                                       *
  *   <----------------  Total speech vector (L_TOTAL)   ----------->     *
  *   <----------------  LPC analysis window (L_WINDOW)  ----------->     *
  *   |                   <-- present frame (L_FRAME) -->                 *
  * old_speech            |              <-- new speech (L_FRAME) -->     *
  * p_window              |              |                                *
  *                     speech           |                                *
  *                             new_speech                                *
  *-----------------------------------------------------------------------*/

  new_speech = old_speech + L_TOTAL - L_FRAME;         /* New speech     */
  speech     = new_speech - L_NEXT;                    /* Present frame  */
  p_window   = old_speech + L_TOTAL - L_WINDOW;        /* For LPC window */

  /* Initialize static pointers */

  wsp    = old_wsp + PIT_MAX;
  exc    = old_exc + PIT_MAX + L_INTERPOL;

  /* Static vectors to zero */

  Set_zero(old_speech, L_TOTAL);
  Set_zero(old_exc, PIT_MAX+L_INTERPOL);
  Set_zero(old_wsp, PIT_MAX);
  Set_zero(mem_w,   M);
  Set_zero(mem_w0,  M);
  Set_zero(mem_zero, M);
  sharp = SHARPMIN;

  /* Initialize lsp_old_q[] */

  Copy(lsp_old, lsp_old_q, M);
  Lsp_encw_reset();
  Init_exc_err();

 return;
}

/*-----------------------------------------------------------------*
 *   Functions Coder_ld8a                                          *
 *            ~~~~~~~~~~                                           *
 *  Coder_ld8a(Word16 ana[]);                                      *
 *                                                                 *
 *   ->Main coder function.                                        *
 *                                                                 *
 *                                                                 *
 *  Input:                                                         *
 *                                                                 *
 *    80 speech data should have beee copy to vector new_speech[]. *
 *    This vector is global and is declared in this function.      *
 *                                                                 *
 *  Ouputs:                                                        *
 *                                                                 *
 *    ana[]      ->analysis parameters.                            *
 *                                                                 *
 *-----------------------------------------------------------------*/

void Coder_ld8a(
     Word16 ana[]       /* output  : Analysis parameters */
)
{

  /* LPC analysis */

  Word16 Aq_t[(MP1)*2];         /* A(z)   quantized for the 2 subframes */
  Word16 Ap_t[(MP1)*2];         /* A(z/gamma)       for the 2 subframes */
  Word16 *Aq, *Ap;              /* Pointer on Aq_t and Ap_t             */

  /* Other vectors */

  Word16 h1[L_SUBFR];            /* Impulse response h1[]              */
  Word16 xn[L_SUBFR];            /* Target vector for pitch search     */
  Word16 xn2[L_SUBFR];           /* Target vector for codebook search  */
  Word16 code[L_SUBFR];          /* Fixed codebook excitation          */
  Word16 y1[L_SUBFR];            /* Filtered adaptive excitation       */
  Word16 y2[L_SUBFR];            /* Filtered fixed codebook excitation */
  Word16 g_coeff[4];             /* Correlations between xn & y1       */

  Word16 g_coeff_cs[5];
  Word16 exp_g_coeff_cs[5];      /* Correlations between xn, y1, & y2
                                     <y1,y1>, -2<xn,y1>,
                                          <y2,y2>, -2<xn,y2>, 2<y1,y2> */

  /* Scalars */

  Word16 i, j, k, i_subfr;
  Word16 T_op, T0, T0_min, T0_max, T0_frac;
  Word16 gain_pit, gain_code, index;
  Word16 temp, taming;
  Word32 L_temp;

/*------------------------------------------------------------------------*
 *  - Perform LPC analysis:                                               *
 *       * autocorrelation + lag windowing                                *
 *       * Levinson-durbin algorithm to find a[]                          *
 *       * convert a[] to lsp[]                                           *
 *       * quantize and code the LSPs                                     *
 *       * find the interpolated LSPs and convert to a[] for the 2        *
 *         subframes (both quantized and unquantized)                     *
 *------------------------------------------------------------------------*/
  {
     /* Temporary vectors */
    Word16 r_l[MP1], r_h[MP1];       /* Autocorrelations low and hi          */
    Word16 rc[M];                    /* Reflection coefficients.             */
    Word16 lsp_new[M], lsp_new_q[M]; /* LSPs at 2th subframe                 */

    /* LP analysis */

    Autocorr(p_window, M, r_h, r_l);              /* Autocorrelations */
    Lag_window(M, r_h, r_l);                      /* Lag windowing    */
    Levinson(r_h, r_l, Ap_t, rc);                 /* Levinson Durbin  */
    Az_lsp(Ap_t, lsp_new, lsp_old);               /* From A(z) to lsp */

    /* LSP quantization */

    Qua_lsp(lsp_new, lsp_new_q, ana);
    ana += 2;                         /* Advance analysis parameters pointer */