view libtwamr/lsp.c @ 478:936a08cc73ce

doc/AMR-library-API: describe the decoder
author Mychaela Falconia <falcon@freecalypso.org>
date Sun, 19 May 2024 21:32:31 +0000
parents 550d3594c878
children
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/*
********************************************************************************
*
*      GSM AMR-NB speech codec   R98   Version 7.6.0   December 12, 2001
*                                R99   Version 3.3.0                
*                                REL-4 Version 4.1.0                
*
********************************************************************************
*
*      File             : lsp.c
*      Purpose          : From A(z) to lsp. LSP quantization and interpolation
*
********************************************************************************
*/

/*
********************************************************************************
*                         MODULE INCLUDE FILE AND VERSION ID
********************************************************************************
*/
#include "namespace.h"
#include "lsp.h"
 
/*
********************************************************************************
*                         INCLUDE FILES
********************************************************************************
*/
#include "tw_amr.h"
#include "typedef.h"
#include "basic_op.h"
#include "oper_32b.h"
#include "q_plsf.h"
#include "memops.h"
#include "az_lsp.h"
#include "int_lpc.h"
#include "no_count.h"
#include "lsp_tab.h"

/*
********************************************************************************
*                         PUBLIC PROGRAM CODE
********************************************************************************
*/
 
/*
**************************************************************************
*
*  Function    : lsp_reset
*
**************************************************************************
*/
void lsp_reset (lspState *st)
{
  /* Init lsp_old[] */
  Copy(lsp_init_data, &st->lsp_old[0], M);

  /* Initialize lsp_old_q[] */
  Copy(st->lsp_old, st->lsp_old_q, M);
  
  /* Reset quantization state */
  Q_plsf_reset(&st->qSt);
}
 
/*************************************************************************
 *
 *   FUNCTION:  lsp()
 *
 ************************************************************************/
int lsp(lspState *st,        /* i/o : State struct                            */
        enum Mode req_mode,  /* i   : requested coder mode                    */
        enum Mode used_mode, /* i   : used coder mode                         */        
        Word16 az[],         /* i/o : interpolated LP parameters Q12          */
        Word16 azQ[],        /* o   : quantization interpol. LP parameters Q12*/
        Word16 lsp_new[],    /* o   : new lsp vector                          */ 
        Word16 **anap        /* o   : analysis parameters                     */)
{
   Word16 lsp_new_q[M];    /* LSPs at 4th subframe           */
   Word16 lsp_mid[M], lsp_mid_q[M];    /* LSPs at 2nd subframe           */
  
   Word16 pred_init_i; /* init index for MA prediction in DTX mode */

   test ();
   if ( sub (req_mode, MR122) == 0)
   {
       Az_lsp (&az[MP1], lsp_mid, st->lsp_old);
       Az_lsp (&az[MP1 * 3], lsp_new, lsp_mid);

       /*--------------------------------------------------------------------*
        * Find interpolated LPC parameters in all subframes (both quantized  *
        * and unquantized).                                                  *
        * The interpolated parameters are in array A_t[] of size (M+1)*4     *
        * and the quantized interpolated parameters are in array Aq_t[]      *
        *--------------------------------------------------------------------*/
       Int_lpc_1and3_2 (st->lsp_old, lsp_mid, lsp_new, az);

       test ();
       if ( sub (used_mode, MRDTX) != 0)
       {
          /* LSP quantization (lsp_mid[] and lsp_new[] jointly quantized) */
          Q_plsf_5 (&st->qSt, lsp_mid, lsp_new, lsp_mid_q, lsp_new_q, *anap);
       
          Int_lpc_1and3 (st->lsp_old_q, lsp_mid_q, lsp_new_q, azQ);
          
          /* Advance analysis parameters pointer */
          (*anap) += add(0,5); move16 ();
       }	 
   }
   else
   {
       Az_lsp(&az[MP1 * 3], lsp_new, st->lsp_old);  /* From A(z) to lsp  */
       
       /*--------------------------------------------------------------------*
        * Find interpolated LPC parameters in all subframes (both quantized  *
        * and unquantized).                                                  *
        * The interpolated parameters are in array A_t[] of size (M+1)*4     *
        * and the quantized interpolated parameters are in array Aq_t[]      *
        *--------------------------------------------------------------------*/
       
       Int_lpc_1to3_2(st->lsp_old, lsp_new, az);
       
       test ();
       if ( sub (used_mode, MRDTX) != 0)
       {
          /* LSP quantization */
          Q_plsf_3(&st->qSt, req_mode, lsp_new, lsp_new_q, *anap, &pred_init_i);
          
          Int_lpc_1to3(st->lsp_old_q, lsp_new_q, azQ);
          
          /* Advance analysis parameters pointer */
          (*anap) += add (0, 3); move16 ();
       }
   }
       
   /* update the LSPs for the next frame */   
   Copy (lsp_new, st->lsp_old, M);
   Copy (lsp_new_q, st->lsp_old_q, M);

   return 0;
}