dec_ld8e.c

E729国际标准的语音编码

/* Version 1.1    Last modified: February 1998 */

/* -------------------------------------------------------------------- */
/*   Decod_ld8e and Init_Decod_ld8e.                        */
/*                                                                      */
/*   (C) Original Copyright 1995, AT&T, France Telecom, NTT,            */
/*   Universite de Sherbrooke.                                          */
/*   All rights reserved.                                               */
/*                                                                      */
/*                                                                      */
/*   Modified to perform higher bit-rate extension of G729 at 11.8 kb/s */
/*                      Bit rate : 11.8 kb/s                            */
/*                                                                      */
/*   (C) Copyright : France Telecom, Universite de Sherbrooke.          */
/*   All rights reserved.                                               */
/*                                                                      */
/* -------------------------------------------------------------------- */



/*-----------------------------------------------------------------*
 *   Functions Init_Decod_ld8e  and Decod_ld8e                     *
 *-----------------------------------------------------------------*/
#include <stdio.h>
#include <stdlib.h>
#include <math.h>

#include "typedef.h"
#include "basic_op.h"
#include "ld8k.h"
#include "ld8e.h"

/*---------------------------------------------------------------*
 *   Decoder constant parameters (defined in "ld8k.h")           *
 *---------------------------------------------------------------*
 *   L_FRAME     : Frame size.                                   *
 *   L_SUBFR     : Sub-frame size.                               *
 *   M           : LPC order.                                    *
 *   MP1         : LPC order+1                                   *
 *   PIT_MIN     : Minimum pitch lag.                            *
 *   PIT_MAX     : Maximum pitch lag.                            *
 *   L_INTERPOL  : Length of filter for interpolation            *
 *   PRM_SIZE    : Size of vector containing analysis parameters *
 *---------------------------------------------------------------*/

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

 /* 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};

        /* Filter's memory */

   static Word16 mem_syn[M_BWD];
   static Word16 sharp;           /* pitch sharpening of previous frame */
   static Word16 prev_T0;         /* integer delay of previous frame    */
   static Word16 prev_T0_frac;    /* integer delay of previous frame    */
   static Word16 gain_code;       /* Code gain                          */
   static Word16 gain_pitch;      /* Pitch gain                         */

    /* for the backward analysis */
    static Word32  rexp[M_BWDP1];
    static Word16 A_bwd_mem[M_BWDP1];
    static Word16 A_t_bwd_mem[2*M_BWDP1];
    static Word16  prev_voicing, prev_bfi, prev_mode, C_fe_fix, C_int ;
    static Word16    prev_filter[M_BWDP1]; /* Previous selected filter */
    static Word16 prev_pitch;
    static Word16 stat_pitch;
    static Word16 pitch_sta, frac_sta;
    /* Last backward A(z) for case of unstable filter */
    static Word16 old_A_bwd[M_BWDP1];
    static Word16 old_rc_bwd[2];

    static Word16   gain_pit_mem;
    static Word16   gain_cod_mem;
    static Word16   c_muting;
    static int      count_bfi;
    static int      stat_bwd;

    static Word16 freq_prev[MA_NP][M];   /* Q13 */

    /* static memory for frame erase operation */
    static Word16 prev_ma;                  /* previous MA prediction coef.*/
    static Word16 prev_lsp[M];           /* previous LSP vector */


/*-----------------------------------------------------------------*
 *   Function Init_Decod_ld8e                                      *
 *            ~~~~~~~~~~~~~~~                                      *
 *                                                                 *
 *   ->Initialization of variables for the decoder section.        *
 *                                                                 *
 *-----------------------------------------------------------------*/

void Init_Decod_ld8e(void)
{


    /* Initialize static pointer */
    exc = old_exc + PIT_MAX + L_INTERPOL;

    /* Static vectors to zero */
     Set_zero(old_exc, PIT_MAX+L_INTERPOL);
     Set_zero(mem_syn, M_BWD);

    sharp  = SHARPMIN;
    prev_T0 = 60;
    prev_T0_frac = 0;
    gain_code = 0;
    gain_pitch = 0;

    Lsp_decw_resete(freq_prev, prev_lsp, &prev_ma);

    Set_zero(A_bwd_mem, M_BWDP1);
    Set_zero(A_t_bwd_mem, M_BWDP1);
    A_bwd_mem[0] = 4096;
    A_t_bwd_mem[0] = 4096;

    prev_voicing = 0;
    prev_bfi = 0;
    prev_mode = 0;
    C_fe_fix = 0;       /* Q12 */
    C_int = 4506;       /* Filter interpolation parameter */
    Set_zero(prev_filter, M_BWDP1);
    prev_filter[0] = 4096;
    prev_pitch = 30;
    stat_pitch = 0;
    Set_zero(old_A_bwd, M_BWDP1);
    old_A_bwd[0]= 4096;
    Set_zero(old_rc_bwd, 2);
    gain_pit_mem = 0;
    gain_cod_mem = 0;
    c_muting = 32767;
    count_bfi = 0;
    stat_bwd = 0;

    return;
}

/*-----------------------------------------------------------------*
 *   Function Decod_ld8e                                           *
 *           ~~~~~~~~~~                                            *
 *   ->Main decoder routine.                                       *
 *                                                                 *
 *-----------------------------------------------------------------*/

void Decod_ld8e (

    Word16  parm[],      /* (i)   : vector of synthesis parameters
                                  parm[0] = bad frame indicator (bfi)  */
    Word16 rate,            /* input   : rate selector/frame  =0 8kbps,= 1 11.8 kbps*/
    Word16  voicing,     /* (i)   : voicing decision from previous frame */
    Word16  synth_buf[],     /* (i/o)   : synthesis speech                     */
    Word16  Az_dec[],       /* (o) : decoded LP filter in 2 subframes     */
    Word16  *T0_first,    /* (o)   : decoded pitch lag in first subframe  */
    Word16 *bwd_dominant,  /* (o)   : */
    Word16 *m_pst         /* (o)   : LPC order for postfilter */
)

{


    /* Scalars */
    Word16 i, j, i_subfr;
    Word16 T0, T0_frac, index;
    Word16 bfi;
    Word16 mode;                   /* Backward / Forward mode indication */
    Word16 g_p, g_c;               /* fixed and adaptive codebook gain */
    Word16 bad_pitch;              /* bad pitch indicator */
    Word16 tmp, tmp1, tmp2;
    Word16 sat_filter;
    Word32 L_temp;
    Word32 energy;


 /* Tables */
    Word16 A_t_bwd[2*M_BWDP1];   /* LPC Backward filter */
    Word16 A_t_fwd[2*MP1];     /* LPC Forward filter */
    Word16 rc_bwd[M_BWD];      /* LPC backward reflection coefficients */
    Word32 r_bwd[M_BWDP1];   /* Autocorrelations (backward) */
    Word16 r_l_bwd[M_BWDP1];   /* Autocorrelations low (backward) */
    Word16 r_h_bwd[M_BWDP1];   /* Autocorrelations high (backward) */
    Word16 lsp_new[M];         /* LSPs             */
    Word16 code[L_SUBFR];      /* ACELP codevector */
    Word16 *pA_t;                /* Pointer on A_t   */
    Word16 stationnary;
    Word16 m_aq;
    Word16 *synth;
    extern        Flag Overflow;

    /* Test bad frame indicator (bfi) */
    bfi = *parm++;

    /* Decoding the Backward/Forward LPC decision */
     /* ------------------------------------------ */
    if( rate == 0) mode = 0;
    else {
        if (bfi != 0) {
            mode = prev_mode; /* Frame erased => mode = previous mode */
            *parm++ = mode;
        }
        else {
            mode = *parm++;
        }
        if(prev_bfi != 0) voicing = prev_voicing;
    }
    if( bfi == 0) {
        c_muting = 32767;
        count_bfi = 0;
    }
    /* -------------------- */
    /* Backward LP analysis */
    /* -------------------- */
    if (rate == 1) {
        /* LPC recursive Window as in G728 */
        autocorr_hyb_window(synth_buf, r_bwd, rexp); /* Autocorrelations */

        Lag_window_bwd(r_bwd, r_h_bwd, r_l_bwd); /* Lag windowing    */

        /* Fixed Point Levinson (as in G729) */
        Levinsone(M_BWD, r_h_bwd, r_l_bwd, &A_t_bwd[M_BWDP1], rc_bwd,
                    old_A_bwd, old_rc_bwd );

        /* Tests saturation of A_t_bwd */
        sat_filter = 0;
        for (i=M_BWDP1; i<2*M_BWDP1; i++) if (A_t_bwd[i] >= 32767) sat_filter = 1;
        if (sat_filter == 1) Copy(A_t_bwd_mem, &A_t_bwd[M_BWDP1], M_BWDP1);
        else Copy(&A_t_bwd[M_BWDP1], A_t_bwd_mem, M_BWDP1);

        /* Additional bandwidth expansion on backward filter */
        Weight_Az(&A_t_bwd[M_BWDP1], GAMMA_BWD, M_BWD, &A_t_bwd[M_BWDP1]);
    }
    /*--------------------------------------------------*
    * Update synthesis signal for next frame.          *
    *--------------------------------------------------*/
    Copy(&synth_buf[L_FRAME], &synth_buf[0], MEM_SYN_BWD);

    if(mode == 1) {
        if ((C_fe_fix != 0)) {
            /* Interpolation of the backward filter after a bad frame */
            /* A_t_bwd(z) = C_fe . A_bwd_mem(z) + (1 - C_fe) . A_t_bwd(z) */
            /* ---------------------------------------------------------- */
            tmp = sub(4096, C_fe_fix);
            pA_t = A_t_bwd + M_BWDP1;
            for (i=0; i<M_BWDP1; i++) {
                L_temp = L_mult(pA_t[i], tmp);
                L_temp = L_shr(L_temp, 13);
                tmp1 = extract_l(L_temp);
                L_temp = L_mult(A_bwd_mem[i], C_fe_fix);
                L_temp = L_shr(L_temp, 13);
                tmp2 = extract_l(L_temp);
                pA_t[i] = add(tmp1, tmp2);
            }
        }
    }


    /* Memorize the last good backward filter when the frame is erased */
    if ((bfi != 0)&&(prev_bfi == 0))
        for (i=0; i<M_BWDP1; i++) A_bwd_mem[i] = A_t_bwd[i+M_BWDP1];

    /* ---------------------------- */
    /* LPC decoding in forward mode */