85 lines
3.0 KiB
C++
85 lines
3.0 KiB
C++
/*
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ITU-T G.729A Speech Coder ANSI-C Source Code
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Version 1.1 Last modified: September 1996
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Copyright (c) 1996,
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AT&T, France Telecom, NTT, Universite de Sherbrooke
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All rights reserved.
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*/
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/*------------------------------------------------------------------------*
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* Function Post_Process() *
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* *
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* Post-processing of output speech. *
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* - 2nd order high pass filter with cut off frequency at 100 Hz. *
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* - Multiplication by two of output speech with saturation. *
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*-----------------------------------------------------------------------*/
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#include "g729_typedef.h"
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#include "g729_basic_op.h"
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#include "g729_oper_32b.h"
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#include "g729_ld8a.h"
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#include "g729_tab_ld8a.h"
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/*------------------------------------------------------------------------*
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* 2nd order high pass filter with cut off frequency at 100 Hz. *
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* Designed with SPPACK efi command -40 dB att, 0.25 ri. *
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* *
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* Algorithm: *
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* *
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* y[i] = b[0]*x[i] + b[1]*x[i-1] + b[2]*x[i-2] *
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* + a[1]*y[i-1] + a[2]*y[i-2]; *
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* *
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* b[3] = {0.93980581E+00, -0.18795834E+01, 0.93980581E+00}; *
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* a[3] = {0.10000000E+01, 0.19330735E+01, -0.93589199E+00}; *
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*-----------------------------------------------------------------------*/
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/* Initialization of values */
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void
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Init_Post_Process (DecState *decoder)
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{
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decoder->y2_hi = 0;
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decoder->y2_lo = 0;
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decoder->y1_hi = 0;
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decoder->y1_lo = 0;
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decoder->x0 = 0;
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decoder->x1 = 0;
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}
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void
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Post_Process (DecState *decoder,
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Word16 signal[], /* input/output signal */
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Word16 lg)
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{ /* length of signal */
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Word16 i, x2;
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Word32 L_tmp;
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for (i = 0; i < lg; i++) {
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x2 = decoder->x1;
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decoder->x1 = decoder->x0;
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decoder->x0 = signal[i];
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/* y[i] = b[0]*x[i] + b[1]*x[i-1] + b[2]*x[i-2] */
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/* + a[1]*y[i-1] + a[2] * y[i-2]; */
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L_tmp = Mpy_32_16 (decoder->y1_hi, decoder->y1_lo, a100[1]);
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L_tmp = L_add (L_tmp, Mpy_32_16 (decoder->y2_hi, decoder->y2_lo, a100[2]));
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L_tmp = L_mac (L_tmp, decoder->x0, b100[0]);
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L_tmp = L_mac (L_tmp, decoder->x1, b100[1]);
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L_tmp = L_mac (L_tmp, x2, b100[2]);
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L_tmp = L_shl (L_tmp, 2); /* Q29 --> Q31 (Q13 --> Q15) */
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/* Multiplication by two of output speech with saturation. */
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signal[i] = wround (L_shl (L_tmp, 1));
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decoder->y2_hi = decoder->y1_hi;
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decoder->y2_lo = decoder->y1_lo;
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L_Extract (L_tmp, &decoder->y1_hi, &decoder->y1_lo);
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}
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return;
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}
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