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view libtwamr/a_refl.h @ 604:54f0f1b74c25

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libgsmhr1 TFO: require BFI=0 and SID=0 for homing In order for a received frame to be recognized as DHF, we need not only the correct bit pattern, but also BFI=0 and SID=0. The BFI=0 requirement should be obvious, while the SID=0 requirement is needed only for HR codec. With FR and EFR, SID classification comes from the payload bits and no separate check is needed - but in HR we get an out-of-band SID ternary flag. When SID=1, no payload bits are used at all; when SID=2, we use only the first 33 bits of the payload. Therefore, it is proper to conditionalize DHF acceptance on SID=0. We already implemented this logic in the just finished full decoder; now bring TFO code into agreement.
author Mychaela Falconia <falcon@freecalypso.org>
date Thu, 04 Dec 2025 19:40:35 +0000
parents 54f6bc41ed10
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             : a_refl.h
*      Purpose          : Convert from direct form coefficients to 
*                         reflection coefficients
*
********************************************************************************
*/
#ifndef a_refl_h
#define a_refl_h "$Id $"

/*
********************************************************************************
*                         INCLUDE FILES
********************************************************************************
*/
#include "typedef.h"

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

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

/*************************************************************************
 *
 *   FUNCTION:  A_Refl()
 *
 *   PURPOSE: Convert from direct form coefficients to reflection coefficients
 *
 *   DESCRIPTION:
 *       Directform coeffs in Q12 are converted to 
 *       reflection coefficients Q15 
 *
 *************************************************************************/
void A_Refl(
   Word16 a[],	      /* i   : Directform coefficients */
   Word16 refl[]      /* o   : Reflection coefficients */
);

#endif