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/*
ITU-T G.729 Annex C+ - Reference C code for floating point
implementation of G.729 Annex C+
(integration of Annexes B, D and E)
Version 2.1 of October 1999
*/
/* ----------------------------------------------------------------- */
/* DUAL BACKWARD / FORWARD LPC STRUCTURE */
/* */
/* switching and decision procedures */
/* */
/* */
/* (C) Copyright 1997 : France Telecom */
/* */
/* ----------------------------------------------------------------- */
/* ----------------------------------------------------------------------- */
/* */
/* Procedures : 1) SET_LPC_MODE */
/* 3) CALC_STAT */
/* */
/* ----------------------------------------------------------------------- */
#include
#include
#include "typedef.h"
#include "ld8k.h"
#include "ld8cp.h"
#include "tabld8cp.h"
static void calc_stat(FLOAT gpred_b, FLOAT gpred_f, int mode,
int prev_mode, INT16 *glob_stat, INT16 *stat_bwd, INT16 *val_stat_bwd);
/* ---------------------------------------------------------------------- */
/* SET_LPC_MODE */
/* */
/* BACKWARD <--> FORWARD DECISION */
/* ---------------------------------------------------------------------- */
void set_lpc_mode ( FLOAT *signal_ptr, /* I Input signal */
FLOAT *a_fwd, /* I Forward LPC filter */
FLOAT *a_bwd, /* I Backward LPC filter */
int *mode, /* O Backward / forward Indication */
FLOAT *lsp_new, /* I LSP vector current frame */
FLOAT *lsp_old, /* I LSP vector previous frame */
int *bwd_dominant, /* O Bwd dominant mode indication */
int prev_mode, /* I previous frame Backward / forward Indication */
FLOAT *prev_filter, /* I previous frame filter */
FLOAT *C_int, /*I/O filter interpolation parameter */
INT16 *glob_stat, /* I/O Mre of global stationnarity */
INT16 *stat_bwd, /* I/O Number of consecutive backward frames */
INT16 *val_stat_bwd /* I/O Value associated with stat_bwd */
)
{
int i;
FLOAT res[L_FRAME];
FLOAT *pa_bwd;
FLOAT gap;
FLOAT gpred_f, gpred_b, gpred_bint;
FLOAT tmp;
FLOAT thresh_lpc;
FLOAT dist_lsp, energy;
pa_bwd = a_bwd + M_BWDP1;
/* Backward filter prediction gain (no interpolation ) */
/* --------------------------------------------------- */
residue(M_BWD,pa_bwd, signal_ptr, res, L_FRAME);
gpred_b = ener_dB(signal_ptr, L_FRAME) - ener_dB(res, L_FRAME);
/* Interpolated LPC filter for transition forward -> backward */
/* (used during 10 frames) ( for the second sub-frame ) */
/* Interpolated backward filter for the first sub-frame */
/* ---------------------------------------------------------- */
int_bwd(a_bwd, prev_filter, C_int);
/* Interpolated backward filter prediction gain */
/* -------------------------------------------- */
residue(M_BWD,a_bwd, signal_ptr, res, L_SUBFR);
residue(M_BWD,pa_bwd, &signal_ptr[L_SUBFR], &res[L_SUBFR], L_SUBFR);
gpred_bint = ener_dB(signal_ptr, L_FRAME) - ener_dB(res, L_FRAME);
/* Forward filter prediction gain */
/* ------------------------------ */
residue(M, a_fwd, signal_ptr, res, L_SUBFR);
residue(M, &a_fwd[MP1], &signal_ptr[L_SUBFR], &res[L_SUBFR], L_SUBFR);
gpred_f = ener_dB(signal_ptr, L_FRAME) - ener_dB(res, L_FRAME);
/* -------------------------------------------------------------- */
/* BACKWARD / FORWARD DECISION */
/* */
/* The Main criterion is based on the prediction gains : */
/* The global stationnarity index is used to adapt the threshold */
/* value " GAP ". */
/* This adaptation is used to favour one mode according to the */
/* stationnarity of the input signal (backward for music and */
/* forward for speech) which avoids too many switches. */
/* */
/* A second criterion based on the LSPs is used to avoid switches */
/* if the successive LPC forward filters are very stationnary */
/* (which is measured a Euclidean distance on LSPs). */
/* */
/* -------------------------------------------------------------- */
/* 1st criterion with prediction gains */
/* ----------------------------------- */
/* Threshold adaptation according to the global stationnarity indicator */
gap = (FLOAT)(*glob_stat) * GAP_FACT;
gap += (F)1.;
if ( (gpred_bint > gpred_f - gap)&& (gpred_b > gpred_f - gap)&&
(gpred_b > (F)0.) && (gpred_bint > (F)0.) ) *mode = 1;
else *mode = 0;
if (*glob_stat < 13000) *mode = 0; /* => Forward mode imposed */
/* 2nd criterion with a distance between 2 successive LSP vectors */
/* -------------------------------------------------------------- */
/* Computation of the LPC distance */
dist_lsp = 0;
for(i=0; i forward forbidden in case of a LPC stationnary */
if ((dist_lsp < thresh_lpc) &&(*mode == 0)&&(prev_mode == 1)
&&(gpred_b > (F)0.)&&(gpred_bint > (F)0.)) {
*mode = 1;
}
/* Low energy frame => Forward mode chosen */
/* --------------------------------------- */
energy = ener_dB(signal_ptr, L_FRAME);
if (energy < THRES_ENERGY) {
*mode = 0;
if (*glob_stat > 13000) *glob_stat = 13000;
}
else tst_bwd_dominant(bwd_dominant, *mode);
/* Adaptation of the global stationnarity indicator */
/* ------------------------------------------------ */
if (energy >= THRES_ENERGY) calc_stat(gpred_b, gpred_f, *mode,
prev_mode, glob_stat, stat_bwd, val_stat_bwd);
if(*mode == 0) *C_int = (F)1.1;
return;
}
void update_bwd(int *mode, /* O Backward / forward Indication */
int *bwd_dominant,/* O Bwd dominant mode indication */
FLOAT *C_int, /*I/O filter interpolation parameter */
INT16 *glob_stat /* I/O Mre of global stationnarity */
)
{
/* BIT RATES IN FORWARD MODE ONLY */
/* ------------------------------ */
if (*glob_stat > 10000) {
*glob_stat -= 2621;
if( *glob_stat < 10000) *glob_stat = 10000 ;
}
*mode = 0;
/* tst_bwd_dominant(bwd_dominant, *mode);*/
*bwd_dominant = 0;
*C_int = (F)1.1;
return;
}
/* ---------------------------------------------------------------------- */
/* CALC_STAT */
/* */
/* Adaptation of the global stationnarity indicator "stat" in [0 ; 32000] */
/* */
/* 0 => very low stationnariy */
/* 32000 => very high stationnarity */
/* */
/* This indicator is based on the performances of */
/* the backward and forward LPC predictions */
/* */
/* ---------------------------------------------------------------------- */
static void calc_stat( FLOAT gpred_b, /* I Backward prediction gain */
FLOAT gpred_f, /* I Forward prediction gain */
int mode, /* I LPC mode indication */
int prev_mode, /* I previous frame LPC mode */
INT16 *glob_stat, /* I/O Mre of global stationnarity */
INT16 *stat_bwd, /* I/O Number of consecutive backward frames */
INT16 *val_stat_bwd/* I/O Value associated with stat_bwd */
)
{
INT16 s_temp;
/* --------------------------------------------------------------- */
/* First adaptation based on previous backward / forward decisions */
/* --------------------------------------------------------------- */
if (mode == 1) { /* Backward stationnary mode */
(*stat_bwd)++;
if(*stat_bwd > 21) *stat_bwd = 21;
if(*val_stat_bwd < 32517) *val_stat_bwd += 250;
else *val_stat_bwd = 32767;
/* after 20 backward frames => increase stat */
if (*stat_bwd == 20) {
if(*glob_stat < 30267) *glob_stat += 2500;
else *glob_stat = 32767;
}
else if (*stat_bwd > 20) *glob_stat += 500;
}
else if ((mode == 0)&&(prev_mode == 1)) { /* Backward -> Forward transition */
/* Transition occurs after less than 20 backward frames => decrease stat */
if (*stat_bwd < 20) {
s_temp = (INT16)(5000 - *val_stat_bwd);
*glob_stat = (INT16)(*glob_stat-s_temp);
}
/* Reset consecutive backward frames counter */
*stat_bwd = 0;
*val_stat_bwd = 0;
}
/* ------------------------------------------- */
/* Second adaptation based on prediction gains */
/* ------------------------------------------- */
if (*glob_stat < 13000) {
if (gpred_b > gpred_f + TH4) *glob_stat += 3200;
else if (gpred_b > gpred_f + TH3) *glob_stat += 2400;
else if (gpred_b > gpred_f + TH2) *glob_stat += 1600;
else if (gpred_b > gpred_f + TH1) *glob_stat += 800;
else if (gpred_b > gpred_f + (F)0.) *glob_stat += 400;
}
if (gpred_b < gpred_f - TH5) *glob_stat -= 6400;
else if (gpred_b < gpred_f - TH4) *glob_stat -= 3200;
else if (gpred_b < gpred_f - TH3) *glob_stat -= 1600;
else if (gpred_b < gpred_f - TH2) *glob_stat -= 800;
else if (gpred_b < gpred_f - TH1) *glob_stat -= 400;
if( *glob_stat > 32000) *glob_stat = 32000;
else {
if(*glob_stat < 0) *glob_stat = 0;
}
return;
}