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view libtwamr/dtx_dec.h @ 581:e2d5cad04cbf

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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 5a1d18542f8a
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             : dtx_dec.h
*      Purpose          : Decode comfort noice when in DTX
*
*****************************************************************************
*/
#ifndef dtx_dec_h
#define dtx_dec_h "$Id $" 
 
/*
*****************************************************************************
*                         INCLUDE FILES
*****************************************************************************
*/
#include "tw_amr.h"
#include "typedef.h"
#include "dtx_common.h"
#include "d_plsf.h"
#include "gc_pred.h"
#include "c_g_aver.h"

/*
*****************************************************************************
*                         LOCAL VARIABLES AND TABLES
*****************************************************************************
*/
enum DTXStateType {SPEECH = 0, DTX, DTX_MUTE};

#define DTX_MAX_EMPTY_THRESH 50

/*
*****************************************************************************
*                         DEFINITION OF DATA TYPES
*****************************************************************************
*/

typedef struct {
   Word16 since_last_sid;
   Word16 true_sid_period_inv;
   Word16 log_en;
   Word16 old_log_en;
   Word32 L_pn_seed_rx; 
   Word16 lsp[M];
   Word16 lsp_old[M]; 
   
   Word16 lsf_hist[M*DTX_HIST_SIZE];
   Word16 lsf_hist_ptr;
   Word16 lsf_hist_mean[M*DTX_HIST_SIZE]; 
   Word16 log_pg_mean;
   Word16 log_en_hist[DTX_HIST_SIZE];
   Word16 log_en_hist_ptr;

   Word16 log_en_adjust;

   Word16 dtxHangoverCount;
   Word16 decAnaElapsedCount;

   Word16 sid_frame;       
   Word16 valid_data;          
   Word16 dtxHangoverAdded;
 
   enum DTXStateType dtxGlobalState;     /* contains previous state */
                                         /* updated in main decoder */ 

   Word16 data_updated;      /* marker to know if CNI data is ever renewed */ 

} dtx_decState;

/*
*****************************************************************************
*                         DECLARATION OF PROTOTYPES
*****************************************************************************
*/
 
/*
**************************************************************************
*
*  Function    : dtx_dec_reset
*  Purpose     : Resets state memory
*  Returns     : 0 on success
*
**************************************************************************
*/
void dtx_dec_reset (dtx_decState *st);
 
/*
**************************************************************************
*
*  Function    : dtx_dec
*  Purpose     :
*  Description :
*                
**************************************************************************
*/
int dtx_dec(
   dtx_decState *st,                /* i/o : State struct                    */
   Word16 mem_syn[],                /* i/o : AMR decoder state               */
   D_plsfState* lsfState,           /* i/o : decoder lsf states              */
   gc_predState* predState,         /* i/o : prediction states               */
   Cb_gain_averageState* averState, /* i/o : CB gain average states          */
   enum DTXStateType new_state,     /* i   : new DTX state                   */    
   enum Mode mode,                  /* i   : AMR mode                        */
   Word16 parm[],                   /* i   : Vector of synthesis parameters  */
   Word16 synth[],                  /* o   : synthesised speech              */
   Word16 A_t[]                     /* o   : decoded LP filter in 4 subframes*/
   );

void dtx_dec_activity_update(dtx_decState *st,
                             Word16 lsf[],
                             Word16 frame[]);

/*
**************************************************************************
*
*  Function    : rx_dtx_handler 
*  Purpose     : reads the frame type and checks history  
*  Description : to decide what kind of DTX/CNI action to perform

**************************************************************************
*/
enum DTXStateType rx_dtx_handler(dtx_decState *st,           /* i/o : State struct */
                                 enum RXFrameType frame_type /* i   : Frame type   */
                                 );

#endif