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view libtwamr/d_gain_c.h @ 605:63f774192906

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gsmhr_decoder_twts002_in(): set BFI=1 SID=1 for invalid SID When a received TW-TS-002 RTP payload indicates invalid SID, which of the 3 possible BFI/SID combinations should we pass to our internal ETSI-based speech decoder or TFO engine? Our original code passed BFI=0 SID=1, but upon further reflection, BFI=1 SID=1 is a better choice. In the corner case where received invalid SID is fed to a full decoder in homed state, setting BFI=1 allows that decoder to emit zeros on PCM and stay homed, instead of launching into full decoding.
author Mychaela Falconia <falcon@freecalypso.org>
date Thu, 04 Dec 2025 21:01:46 +0000
parents a723d9f9f697
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             : d_gain_c.h
*      Purpose          : Decode the fixed codebook gain using the received index.
*
********************************************************************************
*/
#ifndef d_gain_c_h
#define d_gain_c_h "$Id $"
 
/*
********************************************************************************
*                         INCLUDE FILES
********************************************************************************
*/
#include "tw_amr.h"
#include "typedef.h"
#include "gc_pred.h"
 
/*
********************************************************************************
*                         DECLARATION OF PROTOTYPES
********************************************************************************
*/
/*
**************************************************************************
*
*  Function    : d_gain_code
*  Purpose     : Decode the fixed codebook gain using the received index.
*  Description : The received index gives the gain correction factor
*                gamma. The quantized gain is given by   g_q = g0 * gamma
*                where g0 is the predicted gain. To find g0, 4th order
*                MA prediction is applied to the mean-removed innovation
*                energy in dB.
*  Returns     : void
*
**************************************************************************
*/
void d_gain_code (
    gc_predState *pred_state, /* i/o : MA predictor state               */
    enum Mode mode,           /* i   : AMR mode                         */
    Word16 index,             /* i   : received quantization index      */
    Word16 code[],            /* i   : innovation codevector            */
    Word16 *gain_code         /* o   : decoded innovation gain          */
);
 
#endif