/* ** FAAD2 - Freeware Advanced Audio (AAC) Decoder including SBR decoding ** Copyright (C) 2003 M. Bakker, Ahead Software AG, http://www.nero.com ** ** 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. ** ** Any non-GPL usage of this software or parts of this software is strictly ** forbidden. ** ** Commercial non-GPL licensing of this software is possible. ** For more info contact Ahead Software through Mpeg4AAClicense@nero.com. ** ** $Id: tns.c,v 1.22 2003/09/09 18:09:52 menno Exp $ **/ #include "common.h" #include "structs.h" #include "syntax.h" #include "tns.h" #ifdef _MSC_VER #pragma warning(disable:4305) #pragma warning(disable:4244) #endif static real_t tns_coef_0_3[] = { COEF_CONST(0.0), COEF_CONST(0.4338837391), COEF_CONST(0.7818314825), COEF_CONST(0.9749279122), COEF_CONST(-0.9848077530), COEF_CONST(-0.8660254038), COEF_CONST(-0.6427876097), COEF_CONST(-0.3420201433), COEF_CONST(-0.4338837391), COEF_CONST(-0.7818314825), COEF_CONST(-0.9749279122), COEF_CONST(-0.9749279122), COEF_CONST(-0.9848077530), COEF_CONST(-0.8660254038), COEF_CONST(-0.6427876097), COEF_CONST(-0.3420201433) }; static real_t tns_coef_0_4[] = { COEF_CONST(0.0), COEF_CONST(0.2079116908), COEF_CONST(0.4067366431), COEF_CONST(0.5877852523), COEF_CONST(0.7431448255), COEF_CONST(0.8660254038), COEF_CONST(0.9510565163), COEF_CONST(0.9945218954), COEF_CONST(-0.9957341763), COEF_CONST(-0.9618256432), COEF_CONST(-0.8951632914), COEF_CONST(-0.7980172273), COEF_CONST(-0.6736956436), COEF_CONST(-0.5264321629), COEF_CONST(-0.3612416662), COEF_CONST(-0.1837495178) }; static real_t tns_coef_1_3[] = { COEF_CONST(0.0), COEF_CONST(0.4338837391), COEF_CONST(-0.6427876097), COEF_CONST(-0.3420201433), COEF_CONST(0.9749279122), COEF_CONST(0.7818314825), COEF_CONST(-0.6427876097), COEF_CONST(-0.3420201433), COEF_CONST(-0.4338837391), COEF_CONST(-0.7818314825), COEF_CONST(-0.6427876097), COEF_CONST(-0.3420201433), COEF_CONST(-0.7818314825), COEF_CONST(-0.4338837391), COEF_CONST(-0.6427876097), COEF_CONST(-0.3420201433) }; static real_t tns_coef_1_4[] = { COEF_CONST(0.0), COEF_CONST(0.2079116908), COEF_CONST(0.4067366431), COEF_CONST(0.5877852523), COEF_CONST(-0.6736956436), COEF_CONST(-0.5264321629), COEF_CONST(-0.3612416662), COEF_CONST(-0.1837495178), COEF_CONST(0.9945218954), COEF_CONST(0.9510565163), COEF_CONST(0.8660254038), COEF_CONST(0.7431448255), COEF_CONST(-0.6736956436), COEF_CONST(-0.5264321629), COEF_CONST(-0.3612416662), COEF_CONST(-0.1837495178) }; /* TNS decoding for one channel and frame */ void tns_decode_frame(ic_stream *ics, tns_info *tns, uint8_t sr_index, uint8_t object_type, real_t *spec, uint16_t frame_len) { uint8_t w, f, tns_order; int8_t inc; uint16_t bottom, top, start, end, size; uint16_t nshort = frame_len/8; real_t lpc[TNS_MAX_ORDER+1]; if (!ics->tns_data_present) return; for (w = 0; w < ics->num_windows; w++) { bottom = ics->num_swb; for (f = 0; f < tns->n_filt[w]; f++) { top = bottom; bottom = max(top - tns->length[w][f], 0); tns_order = min(tns->order[w][f], TNS_MAX_ORDER); if (!tns_order) continue; tns_decode_coef(tns_order, tns->coef_res[w]+3, tns->coef_compress[w][f], tns->coef[w][f], lpc); start = ics->swb_offset[min(bottom, ics->max_sfb)]; end = ics->swb_offset[min(top, ics->max_sfb)]; if ((size = end - start) <= 0) continue; if (tns->direction[w][f]) { inc = -1; start = end - 1; } else { inc = 1; } tns_ar_filter(&spec[(w*nshort)+start], size, inc, lpc, tns_order); } } } /* TNS encoding for one channel and frame */ void tns_encode_frame(ic_stream *ics, tns_info *tns, uint8_t sr_index, uint8_t object_type, real_t *spec, uint16_t frame_len) { uint8_t w, f, tns_order; int8_t inc; uint16_t bottom, top, start, end, size; uint16_t nshort = frame_len/8; real_t lpc[TNS_MAX_ORDER+1]; if (!ics->tns_data_present) return; for (w = 0; w < ics->num_windows; w++) { bottom = ics->num_swb; for (f = 0; f < tns->n_filt[w]; f++) { top = bottom; bottom = max(top - tns->length[w][f], 0); tns_order = min(tns->order[w][f], TNS_MAX_ORDER); if (!tns_order) continue; tns_decode_coef(tns_order, tns->coef_res[w]+3, tns->coef_compress[w][f], tns->coef[w][f], lpc); start = ics->swb_offset[min(bottom, ics->max_sfb)]; end = ics->swb_offset[min(top, ics->max_sfb)]; if ((size = end - start) <= 0) continue; if (tns->direction[w][f]) { inc = -1; start = end - 1; } else { inc = 1; } tns_ma_filter(&spec[(w*nshort)+start], size, inc, lpc, tns_order); } } } /* Decoder transmitted coefficients for one TNS filter */ static void tns_decode_coef(uint8_t order, uint8_t coef_res_bits, uint8_t coef_compress, uint8_t *coef, real_t *a) { uint8_t i, m; real_t tmp2[TNS_MAX_ORDER+1], b[TNS_MAX_ORDER+1]; /* Conversion to signed integer */ for (i = 0; i < order; i++) { if (coef_compress == 0) { if (coef_res_bits == 3) { tmp2[i] = tns_coef_0_3[coef[i]]; } else { tmp2[i] = tns_coef_0_4[coef[i]]; } } else { if (coef_res_bits == 3) { tmp2[i] = tns_coef_1_3[coef[i]]; } else { tmp2[i] = tns_coef_1_4[coef[i]]; } } } /* Conversion to LPC coefficients */ a[0] = COEF_CONST(1.0); for (m = 1; m <= order; m++) { for (i = 1; i < m; i++) /* loop only while i 0; j--) state[j] = state[j-1]; state[0] = y; *spectrum = y; spectrum += inc; } } static void tns_ma_filter(real_t *spectrum, uint16_t size, int8_t inc, real_t *lpc, uint8_t order) { /* - Simple all-zero filter of order "order" defined by y(n) = x(n) + a(2)*x(n-1) + ... + a(order+1)*x(n-order) - The state variables of the filter are initialized to zero every time - The output data is written over the input data ("in-place operation") - An input vector of "size" samples is processed and the index increment to the next data sample is given by "inc" */ uint8_t j; uint16_t i; real_t y, state[TNS_MAX_ORDER]; for (i = 0; i < order; i++) state[i] = REAL_CONST(0.0); for (i = 0; i < size; i++) { y = *spectrum; for (j = 0; j < order; j++) y += MUL_R_C(state[j], lpc[j+1]); for (j = order-1; j > 0; j--) state[j] = state[j-1]; state[0] = *spectrum; *spectrum = y; spectrum += inc; } }