lspgetq.c

语音编码G.729 语音编码G.729

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

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

/*----------------------------------------------------------------------------
 * lsp_get_quant - reconstruct quantized LSP parameter and check the stabilty
 *----------------------------------------------------------------------------
 */

void lsp_get_quant(
 const FLOAT  lspcb1[][M],    /*input : first stage LSP codebook     */
 const FLOAT  lspcb2[][M],    /*input : Second stage LSP codebook    */
 int    code0,          /*input : selected code of first stage */
 int    code1,          /*input : selected code of second stage*/
 int    code2,          /*input : selected code of second stage*/
 const FLOAT  fg[][M],        /*input : MA prediction coef.          */
 FLOAT  freq_prev[][M], /*input : previous LSP vector          */
 FLOAT  lspq[],         /*output: quantized LSP parameters     */
 const FLOAT  fg_sum[]        /*input : present MA prediction coef.  */
)
{
   int  j;
   FLOAT  buf[M];


   for(j=0; j<NC; j++)
     buf[j] = lspcb1[code0][j] + lspcb2[code1][j];
   for(j=NC; j<M; j++)
     buf[j] = lspcb1[code0][j] + lspcb2[code2][j];

   /* check */
   lsp_expand_1_2(buf, GAP1);
   lsp_expand_1_2(buf, GAP2);

   /* reconstruct quantized LSP parameters */
   lsp_prev_compose(buf, lspq, fg, freq_prev, fg_sum);

   lsp_prev_update(buf, freq_prev);

   lsp_stability( lspq );  /* check the stabilty */
}

/*----------------------------------------------------------------------------
 * lsp_expand_1  - check for lower (0-4)
 *----------------------------------------------------------------------------
 */
void lsp_expand_1(
 FLOAT  buf[],          /* in/out: lsp vectors  */
 FLOAT gap
)
{
   int   j;
   FLOAT diff, tmp;

   for(j=1; j<NC; j++) {
      diff = buf[j-1] - buf[j];
      tmp  = (diff + gap) * (F)0.5;
      if(tmp >  0) {
         buf[j-1] -= tmp;
         buf[j]   += tmp;
      }
   }
}

/*----------------------------------------------------------------------------
 * lsp_expand_2 - check for higher (5-9)
 *----------------------------------------------------------------------------
 */
void lsp_expand_2(
 FLOAT  buf[],          /*in/out: lsp vectors  */
 FLOAT gap

)
{
   int   j;
   FLOAT diff, tmp;

   for(j=NC; j<M; j++) {
      diff = buf[j-1] - buf[j];
      tmp  = (diff + gap) * (F)0.5;
      if(tmp >  0) {
         buf[j-1] -= tmp;
         buf[j]   += tmp;
      }
   }
}

/*----------------------------------------------------------------------------
 * lsp_expand_1_2 - ..
 *----------------------------------------------------------------------------
 */
void lsp_expand_1_2(
 FLOAT  buf[],          /*in/out: LSP parameters  */
 FLOAT  gap             /*input      */
)
{
   int   j;
   FLOAT diff, tmp;

   for(j=1; j<M; j++) {
      diff = buf[j-1] - buf[j];
      tmp  = (diff + gap) * (F)0.5;
      if(tmp >  0) {
         buf[j-1] -= tmp;
         buf[j]   += tmp;
      }
   }
}



/*
  Functions which use previous LSP parameter (freq_prev).
*/


/*
  compose LSP parameter from elementary LSP with previous LSP.
*/
void lsp_prev_compose(
  FLOAT lsp_ele[],             /* (i) Q13 : LSP vectors                 */
  FLOAT lsp[],                 /* (o) Q13 : quantized LSP parameters    */
  const FLOAT fg[][M],               /* (i) Q15 : MA prediction coef.         */
  FLOAT freq_prev[][M],        /* (i) Q13 : previous LSP vector         */
  const FLOAT fg_sum[]               /* (i) Q15 : present MA prediction coef. */
)
{
   int j, k;

   for(j=0; j<M; j++) {
      lsp[j] = lsp_ele[j] * fg_sum[j];
      for(k=0; k<MA_NP; k++) lsp[j] += freq_prev[k][j]*fg[k][j];
   }
}

/*
  extract elementary LSP from composed LSP with previous LSP
*/
void lsp_prev_extract(
  FLOAT lsp[M],                /* (i) Q13 : unquantized LSP parameters  */
  FLOAT lsp_ele[M],            /* (o) Q13 : target vector               */
  const FLOAT fg[MA_NP][M],          /* (i) Q15 : MA prediction coef.         */
  FLOAT freq_prev[MA_NP][M],   /* (i) Q13 : previous LSP vector         */
  const FLOAT fg_sum_inv[M]          /* (i) Q12 : inverse previous LSP vector */
)
{
  int j, k;

  /*----- compute target vectors for each MA coef.-----*/
  for( j = 0 ; j < M ; j++ ) {
      lsp_ele[j]=lsp[j];
      for ( k = 0 ; k < MA_NP ; k++ )
         lsp_ele[j] -= freq_prev[k][j] * fg[k][j];
      lsp_ele[j] *= fg_sum_inv[j];
   }
}

/*
  update previous LSP parameter
*/
void lsp_prev_update(
  FLOAT lsp_ele[M],             /* input : LSP vectors           */
  FLOAT freq_prev[MA_NP][M]     /* input/output: previous LSP vectors  */
)
{
  int k;

  for ( k = MA_NP-1 ; k > 0 ; k-- )
    copy(freq_prev[k-1], freq_prev[k], M);

  copy(lsp_ele, freq_prev[0], M);
}

/*----------------------------------------------------------------------------
 * lsp_stability - check stability of lsp coefficients
 *----------------------------------------------------------------------------
 */
void lsp_stability(
 FLOAT  buf[]           /*in/out: LSP parameters  */
)
{
   int   j;
   FLOAT diff, tmp;


   for(j=0; j<M-1; j++) {
      diff = buf[j+1] - buf[j];
      if( diff < (F)0. ) {
         tmp      = buf[j+1];
         buf[j+1] = buf[j];
         buf[j]   = tmp;
      }
   }

   if( buf[0] < L_LIMIT ) {
      buf[0] = L_LIMIT;
      printf("warning LSP Low \n");
   }
   for(j=0; j<M-1; j++) {
      diff = buf[j+1] - buf[j];
      if( diff < GAP3 ) {
        buf[j+1] = buf[j]+ GAP3;
      }
   }
   if( buf[M-1] > M_LIMIT ) {
      buf[M-1] = M_LIMIT;
      printf("warning LSP High \n");
   }
}