ref: 3def44dfa46085e1d8ccaf9688a6817853bfcee9
dir: /libfaad/ic_predict.c/
/* ** FAAD - Freeware Advanced Audio Decoder ** Copyright (C) 2002 M. Bakker ** ** This program is free software; you can redistribute it and/or modify ** it under the terms of the GNU General Public License as published by ** the Free Software Foundation; either version 2 of the License, or ** (at your option) any later version. ** ** This program is distributed in the hope that it will be useful, ** but WITHOUT ANY WARRANTY; without even the implied warranty of ** MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the ** GNU General Public License for more details. ** ** You should have received a copy of the GNU General Public License ** along with this program; if not, write to the Free Software ** Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA. ** ** $Id: ic_predict.c,v 1.1 2002/01/14 19:15:56 menno Exp $ **/ #ifdef __ICL #include <mathf.h> #else #include <math.h> #endif #include "syntax.h" #include "ic_predict.h" #include "pns.h" static void flt_round_inf(float *pf) { int flg; unsigned long tmp; float *pt = (float *)&tmp; *pt = *pf; flg = tmp & (unsigned long)0x00008000; tmp &= (unsigned long)0xffff0000; *pf = *pt; /* round 1/2 lsb toward infinity */ if (flg) { tmp &= (unsigned long)0xff800000; /* extract exponent and sign */ tmp |= (unsigned long)0x00010000; /* insert 1 lsb */ *pf += *pt; /* add 1 lsb and elided one */ tmp &= (unsigned long)0xff800000; /* extract exponent and sign */ *pf -= *pt; /* subtract elided one */ } } static void ic_predict(pred_state *state, float input, float *output, int pred) { float dr1, predictedvalue; float e0, e1; float k1, k2; float *r; float *KOR; float *VAR; r = state->r; /* delay elements */ KOR = state->KOR; /* correlations */ VAR = state->VAR; /* variances */ k1 = KOR[0]/VAR[0]*B; if (pred) { /* only needed for the actual predicted value, k1 is always needed */ k2 = KOR[1]/VAR[1]*B; predictedvalue = k1*r[0] + k2*r[1]; flt_round_inf(&predictedvalue); *output = input + predictedvalue; } else { *output = input; } /* calculate new state data */ e0 = *output; e1 = e0 - k1 * r[0]; dr1 = k1 * e0; VAR[0] = ALPHA * VAR[0] + (0.5f)*(r[0]*r[0] + e0*e0); KOR[0] = ALPHA * KOR[0] + r[0]*e0; VAR[1] = ALPHA * VAR[1] + (0.5f)*(r[1]*r[1] + e1*e1); KOR[1] = ALPHA * KOR[1] + r[1]*e1; r[1] = A * (r[0]-dr1); r[0] = A * e0; } static void reset_pred_state(pred_state *state) { state->r[0] = 0.0f; state->r[1] = 0.0f; state->KOR[0] = 0.0f; state->KOR[1] = 0.0f; state->VAR[0] = 1.0f; state->VAR[1] = 1.0f; } void pns_reset_pred_state(ic_stream *ics, pred_state *state) { int sfb, g, b, i; int offs, size; /* prediction only for long blocks */ if (ics->window_sequence == EIGHT_SHORT_SEQUENCE) return; for (g = 0; g < ics->num_window_groups; g++) { for (b = 0; b < ics->window_group_length[g]; b++) { for (sfb = 0; sfb < ics->max_sfb; sfb++) { if (is_noise(ics, g, sfb)) { offs = ics->swb_offset[sfb]; size = ics->swb_offset[sfb+1] - offs; for (i = offs; i < size; i++) reset_pred_state(&state[i]); } } } } } void reset_all_predictors(pred_state *state) { int i; for (i = 0; i < 1024; i++) reset_pred_state(&state[i]); } /* intra channel prediction */ void ic_prediction(ic_stream *ics, float *spec, pred_state *state) { int sfb, bin; if (ics->window_sequence == EIGHT_SHORT_SEQUENCE) { reset_all_predictors(state); } else { for (sfb = 0; sfb < ics->pred.limit; sfb++) { int low = ics->swb_offset[sfb]; int high = ics->swb_offset[sfb+1]; for (bin = low; bin < high; bin++) { ic_predict(&state[bin], spec[bin], &spec[bin], (ics->predictor_data_present && ics->pred.prediction_used[sfb])); } } if (ics->predictor_data_present) { if (ics->pred.predictor_reset) { for (bin = ics->pred.predictor_reset_group_number - 1; bin < 1024; bin += 30) { reset_pred_state(&state[bin]); } } } } }