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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 1d2b39027b70
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             : qgain475.h
*      Purpose          : Quantization of pitch and codebook gains for MR475.
*
********************************************************************************
*/
#ifndef qgain475_h
#define qgain475_h "$Id $"
 
/*
********************************************************************************
*                         INCLUDE FILES
********************************************************************************
*/
#include "typedef.h"
#include "gc_pred.h"

/*
********************************************************************************
*                         DECLARATION OF PROTOTYPES
********************************************************************************
*/

/*************************************************************************
 *
 * FUNCTION:  MR475_update_unq_pred()
 *
 * PURPOSE:   use optimum codebook gain and update "unquantized"
 *            gain predictor with the (bounded) prediction error
 *
 *************************************************************************/
void 
MR475_update_unq_pred(
    gc_predState *pred_st, /* i/o: gain predictor state struct            */
    Word16 exp_gcode0,     /* i  : predicted CB gain (exponent),      Q0  */
    Word16 frac_gcode0,    /* i  : predicted CB gain (fraction),      Q15 */
    Word16 cod_gain_exp,   /* i  : optimum codebook gain (exponent),  Q0  */
    Word16 cod_gain_frac   /* i  : optimum codebook gain (fraction),  Q15 */
);

/*************************************************************************
 *
 * FUNCTION:  MR475_gain_quant()
 *
 * PURPOSE: Quantization of pitch and codebook gains for two subframes
 *          (using predicted codebook gain)
 *
 *************************************************************************/

Word16
MR475_gain_quant(              /* o  : index of quantization.                 */
    gc_predState *pred_st,     /* i/o: gain predictor state struct            */
      
                               /* data from subframe 0 (or 2) */
    Word16 sf0_exp_gcode0,     /* i  : predicted CB gain (exponent),      Q0  */
    Word16 sf0_frac_gcode0,    /* i  : predicted CB gain (fraction),      Q15 */
    Word16 sf0_exp_coeff[],    /* i  : energy coeff. (5), exponent part,  Q0  */
    Word16 sf0_frac_coeff[],   /* i  : energy coeff. (5), fraction part,  Q15 */
                               /*      (frac_coeff and exp_coeff computed in  */
                               /*       calc_filt_energies())                 */
    Word16 sf0_exp_target_en,  /* i  : exponent of target energy,         Q0  */
    Word16 sf0_frac_target_en, /* i  : fraction of target energy,         Q15 */
      
                               /* data from subframe 1 (or 3) */
    Word16 sf1_code_nosharp[], /* i  : innovative codebook vector (L_SUBFR)   */
                               /*      (whithout pitch sharpening)            */
    Word16 sf1_exp_gcode0,     /* i  : predicted CB gain (exponent),      Q0  */
    Word16 sf1_frac_gcode0,    /* i  : predicted CB gain (fraction),      Q15 */
    Word16 sf1_exp_coeff[],    /* i  : energy coeff. (5), exponent part,  Q0  */
    Word16 sf1_frac_coeff[],   /* i  : energy coeff. (5), fraction part,  Q15 */
                               /*      (frac_coeff and exp_coeff computed in  */
                               /*       calc_filt_energies())                 */
    Word16 sf1_exp_target_en,  /* i  : exponent of target energy,         Q0  */
    Word16 sf1_frac_target_en, /* i  : fraction of target energy,         Q15 */

    Word16 gp_limit,           /* i  : pitch gain limit                       */

    Word16 *sf0_gain_pit,      /* o  : Pitch gain,                        Q14 */
    Word16 *sf0_gain_cod,      /* o  : Code gain,                         Q1  */
      
    Word16 *sf1_gain_pit,      /* o  : Pitch gain,                        Q14 */
    Word16 *sf1_gain_cod       /* o  : Code gain,                         Q1  */
);
#endif