ref: 3254623f0745837118e0d5d739fa6c402fd5b9d3
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 1.11 2003/06/23 15:21:19 menno Exp $ **/ #include "common.h" #include "structs.h" #ifdef MAIN_DEC #include "syntax.h" #include "ic_predict.h" #include "pns.h" static void flt_round(real_t *pf) { /* more stable version for clever compilers like gcc 3.x */ int32_t flg; uint32_t tmp, tmp1, tmp2; tmp = *(uint32_t*)pf; flg = tmp & (uint32_t)0x00008000; tmp &= (uint32_t)0xffff0000; tmp1 = tmp; /* round 1/2 lsb toward infinity */ if (flg) { tmp &= (uint32_t)0xff800000; /* extract exponent and sign */ tmp |= (uint32_t)0x00010000; /* insert 1 lsb */ tmp2 = tmp; /* add 1 lsb and elided one */ tmp &= (uint32_t)0xff800000; /* extract exponent and sign */ *pf = *(real_t*)&tmp1+*(real_t*)&tmp2-*(real_t*)&tmp;/* subtract elided one */ } else { *pf = *(real_t*)&tmp; } } static void ic_predict(pred_state *state, real_t input, real_t *output, uint8_t pred) { real_t dr1, predictedvalue; real_t e0, e1; real_t k1, k2; real_t *r; real_t *KOR; real_t *VAR; r = state->r; /* delay elements */ KOR = state->KOR; /* correlations */ VAR = state->VAR; /* variances */ if (VAR[0] <= 1) k1 = 0; else k1 = KOR[0]/VAR[0]*B; if (pred) { /* only needed for the actual predicted value, k1 is always needed */ if (VAR[1] <= 1) k2 = 0; else k2 = KOR[1]/VAR[1]*B; predictedvalue = MUL(k1, r[0]) + MUL(k2, r[1]); flt_round(&predictedvalue); *output = input + predictedvalue; } else { *output = input; } /* calculate new state data */ e0 = *output; e1 = e0 - MUL(k1, r[0]); dr1 = MUL(k1, e0); VAR[0] = MUL(ALPHA, VAR[0]) + MUL(REAL_CONST(0.5), (MUL(r[0], r[0]) + MUL(e0, e0))); KOR[0] = MUL(ALPHA, KOR[0]) + MUL(r[0], e0); VAR[1] = MUL(ALPHA, VAR[1]) + MUL(REAL_CONST(0.5), (MUL(r[1], r[1]) + MUL(e1, e1))); KOR[1] = MUL(ALPHA, KOR[1]) + MUL(r[1], e1); r[1] = MUL(A, (r[0]-dr1)); r[0] = MUL(A, e0); } static void reset_pred_state(pred_state *state) { state->r[0] = 0; state->r[1] = 0; state->KOR[0] = 0; state->KOR[1] = 0; state->VAR[0] = REAL_CONST(1.0); state->VAR[1] = REAL_CONST(1.0); } void pns_reset_pred_state(ic_stream *ics, pred_state *state) { uint8_t sfb, g, b; uint16_t i, offs, offs2; /* 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]; offs2 = ics->swb_offset[sfb+1]; for (i = offs; i < offs2; i++) reset_pred_state(&state[i]); } } } } } void reset_all_predictors(pred_state *state, uint16_t frame_len) { uint16_t i; for (i = 0; i < frame_len; i++) reset_pred_state(&state[i]); } /* intra channel prediction */ void ic_prediction(ic_stream *ics, real_t *spec, pred_state *state, uint16_t frame_len) { uint8_t sfb; uint16_t bin; if (ics->window_sequence == EIGHT_SHORT_SEQUENCE) { reset_all_predictors(state, frame_len); } else { for (sfb = 0; sfb < ics->pred.limit; sfb++) { uint16_t low = ics->swb_offset[sfb]; uint16_t 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 < frame_len; bin += 30) { reset_pred_state(&state[bin]); } } } } } #endif