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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 48c7f8e8c9af
children
line wrap: on
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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             : p_ol_wgh.h
*      Purpose          : Compute the open loop pitch lag with weighting.
*
********************************************************************************
*/
#ifndef p_ol_wgh_h
#define p_ol_wgh_h "$Id $"
 
/*
********************************************************************************
*                         INCLUDE FILES
********************************************************************************
*/
#include "tw_amr.h"
#include "typedef.h"
#include "vad.h"

/*
********************************************************************************
*                         DEFINITION OF DATA TYPES
********************************************************************************
*/
/* state variable */
typedef struct {
   Word16 old_T0_med;
   Word16 ada_w;
   Word16 wght_flg; 
} pitchOLWghtState;

/*
********************************************************************************
*                         DECLARATION OF PROTOTYPES
********************************************************************************
*/
 
void p_ol_wgh_reset (pitchOLWghtState *st);
/* reset of pre processing state (i.e. set state memory to zero)
   returns 0 on success
 */

Word16 Pitch_ol_wgh (     /* o   : open loop pitch lag                            */
    pitchOLWghtState *st, /* i/o : State struct                                   */
    vadState *vadSt,      /* i/o : VAD state struct                               */
    Word16 signal[],      /* i   : signal used to compute the open loop pitch     */
                          /*       signal[-pit_max] to signal[-1] should be known */
    Word16 pit_min,       /* i   : minimum pitch lag                              */
    Word16 pit_max,       /* i   : maximum pitch lag                              */
    Word16 L_frame,       /* i   : length of frame to compute pitch               */
    Word16 old_lags[],    /* i   : history with old stored Cl lags                */
    Word16 ol_gain_flg[], /* i   : OL gain flag                                   */
    Word16 idx,           /* i   : index                                          */
    Flag dtx              /* i   : dtx flag; use dtx=1, do not use dtx=0          */
    );
 
#endif