view libtwamr/lsp.c @ 581:e2d5cad04cbf

libgsmhr1 RxFE: store CN R0+LPC separately from speech In the original GSM 06.06 code the ECU for speech mode is entirely separate from the CN generator, maintaining separate state. (The main intertie between them is the speech vs CN state variable, distinguishing between speech and CN BFIs, in addition to the CN-specific function of distinguishing between initial and update SIDs.) In the present RxFE implementation I initially thought that we could use the same saved_frame buffer for both ECU and CN, overwriting just the first 4 params (R0 and LPC) when a valid SID comes in. However, I now realize it was a bad idea: the original code has a corner case (long sequence of speech-mode BFIs to put the ECU in state 6, then SID and CN-mode BFIs, then a good speech frame) that would be broken by that buffer reuse approach. We could eliminate this corner case by resetting the ECU state when passing through a CN insertion period, but doing so would needlessly increase the behavioral diffs between GSM 06.06 and our version. Solution: use a separate CN-specific buffer for CN R0+LPC parameters, and match the behavior of GSM 06.06 code in this regard.
author Mychaela Falconia <falcon@freecalypso.org>
date Thu, 13 Feb 2025 10:02:45 +0000
parents 550d3594c878
children
line wrap: on
line source

/*
********************************************************************************
*
*      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;
}