FreeCalypso > hg > gsm-codec-lib
view libtwamr/post_pro.c @ 419:2a094af3d384
libtwamr: implement encoder top level
author | Mychaela Falconia <falcon@freecalypso.org> |
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date | Tue, 07 May 2024 04:51:04 +0000 |
parents | a0f914a28371 |
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 : post_pro.c * Purpose : Postprocessing of output speech. * * - 2nd order high pass filtering with cut * off frequency at 60 Hz. * - Multiplication of output by two. * ******************************************************************************** */ /* ******************************************************************************** * MODULE INCLUDE FILE AND VERSION ID ******************************************************************************** */ #include "namespace.h" #include "post_pro.h" /* ******************************************************************************** * INCLUDE FILES ******************************************************************************** */ #include "typedef.h" #include "basic_op.h" #include "oper_32b.h" #include "no_count.h" /* ******************************************************************************** * LOCAL VARIABLES AND TABLES ******************************************************************************** */ /* filter coefficients (fc = 60 Hz) */ static const Word16 b[3] = {7699, -15398, 7699}; static const Word16 a[3] = {8192, 15836, -7667}; /* ******************************************************************************** * PUBLIC PROGRAM CODE ******************************************************************************** */ /************************************************************************* * * Function: Post_Process_reset * Purpose: Initializes state memory to zero * ************************************************************************** */ void Post_Process_reset (Post_ProcessState *state) { state->y2_hi = 0; state->y2_lo = 0; state->y1_hi = 0; state->y1_lo = 0; state->x0 = 0; state->x1 = 0; } /************************************************************************* * * FUNCTION: Post_Process() * * PURPOSE: Postprocessing of input speech. * * DESCRIPTION: * - 2nd order high pass filtering with cut off frequency at 60 Hz. * - Multiplication of output by two. * * Algorithm: * * y[i] = b[0]*x[i]*2 + b[1]*x[i-1]*2 + b[2]*x[i-2]*2 * + a[1]*y[i-1] + a[2]*y[i-2]; * * *************************************************************************/ int Post_Process ( Post_ProcessState *st, /* i/o : post process state */ Word16 signal[], /* i/o : signal */ Word16 lg /* i : length of signal */ ) { Word16 i, x2; Word32 L_tmp; test (); test (); for (i = 0; i < lg; i++) { x2 = st->x1; move16 (); st->x1 = st->x0; move16 (); st->x0 = signal[i]; move16 (); /* y[i] = b[0]*x[i]*2 + b[1]*x[i-1]*2 + b140[2]*x[i-2]/2 */ /* + a[1]*y[i-1] + a[2] * y[i-2]; */ L_tmp = Mpy_32_16 (st->y1_hi, st->y1_lo, a[1]); L_tmp = L_add (L_tmp, Mpy_32_16 (st->y2_hi, st->y2_lo, a[2])); L_tmp = L_mac (L_tmp, st->x0, b[0]); L_tmp = L_mac (L_tmp, st->x1, b[1]); L_tmp = L_mac (L_tmp, x2, b[2]); L_tmp = L_shl (L_tmp, 2); /* Multiplication by two of output speech with saturation. */ signal[i] = round(L_shl(L_tmp, 1)); move16 (); st->y2_hi = st->y1_hi; move16 (); st->y2_lo = st->y1_lo; move16 (); L_Extract (L_tmp, &st->y1_hi, &st->y1_lo); } return 0; }