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view libtwamr/c2_9pf.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 ee64aabcc7a0
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             : c2_9pf.h
*      Purpose          : Searches a 9 bit algebraic codebook containing 
*                         2 pulses in a frame of 40 samples.
*
*****************************************************************************
*/
#ifndef c2_9pf_h
#define c2_9pf_h "$Id $"
 
/*
*****************************************************************************
*                         INCLUDE FILES
*****************************************************************************
*/
#include "typedef.h"

/*
*****************************************************************************
*                         LOCAL VARIABLES AND TABLES
*****************************************************************************
*/

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

/*
*****************************************************************************
*                         DECLARATION OF PROTOTYPES
*****************************************************************************
*/
/*************************************************************************
 *
 *  FUNCTION:  code_2i40_9bits()
 *
 *  PURPOSE:  Searches a 9 bit algebraic codebook containing 2 pulses
 *            in a frame of 40 samples.
 *
 *  DESCRIPTION:
 *    The code length is 40, containing 2 nonzero pulses: i0...i1.
 *    All pulses can have two possible amplitudes: +1 or -1.
 *    Pulse i0 can have 8 possible positions, pulse i1 can have
 *    8 positions. Also coded is which track pair should be used,
 *    i.e. first or second pair. Where each pair contains 2 tracks.
 *
 *     First subframe:
 *     first   i0 :  0, 5, 10, 15, 20, 25, 30, 35.
 *             i1 :  2, 7, 12, 17, 22, 27, 32, 37.
 *     second  i0 :  1, 6, 11, 16, 21, 26, 31, 36.
 *             i1 :  3, 8, 13, 18, 23, 28, 33, 38.
 *
 *     Second subframe:
 *     first   i0 :  0, 5, 10, 15, 20, 25, 30, 35.
 *             i1 :  3, 8, 13, 18, 23, 28, 33, 38.
 *     second  i0 :  2, 7, 12, 17, 22, 27, 32, 37.
 *             i1 :  4, 9, 14, 19, 24, 29, 34, 39.
 *
 *     Third subframe:
 *     first   i0 :  0, 5, 10, 15, 20, 25, 30, 35.
 *             i1 :  2, 7, 12, 17, 22, 27, 32, 37.
 *     second  i0 :  1, 6, 11, 16, 21, 26, 31, 36.
 *             i1 :  4, 9, 14, 19, 24, 29, 34, 39.
 *
 *     Fourth subframe:
 *     first   i0 :  0, 5, 10, 15, 20, 25, 30, 35.
 *             i1 :  3, 8, 13, 18, 23, 28, 33, 38.
 *     second  i0 :  1, 6, 11, 16, 21, 26, 31, 36.
 *             i1 :  4, 9, 14, 19, 24, 29, 34, 39.
 *
 *************************************************************************/

Word16 code_2i40_9bits(
    Word16 subNr,       /* i : subframe number                               */
    Word16 x[],         /* i : target vector                                 */
    Word16 h[],         /* i : impulse response of weighted synthesis filter */
                        /*     h[-L_subfr..-1] must be set to zero.          */
    Word16 T0,          /* i : Pitch lag                                     */
    Word16 pitch_sharp, /* i : Last quantized pitch gain                     */
    Word16 code[],      /* o : Innovative codebook                           */
    Word16 y[],         /* o : filtered fixed codebook excitation            */
    Word16 * sign       /* o : Signs of 2 pulses                             */
);

#endif