ref: 584e5f7e8212f70af2d8480f580ce7005a6579c5
dir: /libfaad/tns.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: tns.c,v 1.18 2002/11/28 18:48:30 menno Exp $ **/ #include "common.h" #include "structs.h" #include "syntax.h" #include "tns.h" #ifdef FIXED_POINT static real_t tns_coef_0_3[] = { 0x0, 0x6F13013, 0xC8261BA, 0xF994E02, 0xF03E3A3A, 0xF224C28C, 0xF5B72457, 0xFA8715E3, 0xF90ECFED, 0xF37D9E46, 0xF066B1FE, 0xF066B1FE, 0xF03E3A3A, 0xF224C28C, 0xF5B72457, 0xFA8715E3 }; static real_t tns_coef_0_4[] = { 0x0, 0x3539B35, 0x681FE48, 0x9679182, 0xBE3EBD4, 0xDDB3D74, 0xF378709, 0xFE98FCA, 0xF011790B, 0xF09C5CB7, 0xF1AD6942, 0xF33B524A, 0xF5388AEB, 0xF793BBDF, 0xFA385AA9, 0xFD0F5CAB }; static real_t tns_coef_1_3[] = { 0x0, 0x6F13013, 0xF5B72457, 0xFA8715E3, 0xF994E02, 0xC8261BA, 0xF5B72457, 0xFA8715E3, 0xF90ECFED, 0xF37D9E46, 0xF5B72457, 0xFA8715E3, 0xF37D9E46, 0xF90ECFED, 0xF5B72457, 0xFA8715E3 }; static real_t tns_coef_1_4[] = { 0x0, 0x3539B35, 0x681FE48, 0x9679182, 0xF5388AEB, 0xF793BBDF, 0xFA385AA9, 0xFD0F5CAB, 0xFE98FCA, 0xF378709, 0xDDB3D74, 0xBE3EBD4, 0xF5388AEB, 0xF793BBDF, 0xFA385AA9, 0xFD0F5CAB }; #else #ifdef _MSC_VER #pragma warning(disable:4305) #pragma warning(disable:4244) #endif static real_t tns_coef_0_3[] = { 0.0, 0.4338837391, 0.7818314825, 0.9749279122, -0.9848077530, -0.8660254038, -0.6427876097, -0.3420201433, -0.4338837391, -0.7818314825, -0.9749279122, -0.9749279122, -0.9848077530, -0.8660254038, -0.6427876097, -0.3420201433 }; static real_t tns_coef_0_4[] = { 0.0, 0.2079116908, 0.4067366431, 0.5877852523, 0.7431448255, 0.8660254038, 0.9510565163, 0.9945218954, -0.9957341763, -0.9618256432, -0.8951632914, -0.7980172273, -0.6736956436, -0.5264321629, -0.3612416662, -0.1837495178 }; static real_t tns_coef_1_3[] = { 0.0, 0.4338837391, -0.6427876097, -0.3420201433, 0.9749279122, 0.7818314825, -0.6427876097, -0.3420201433, -0.4338837391, -0.7818314825, -0.6427876097, -0.3420201433, -0.7818314825, -0.4338837391, -0.6427876097, -0.3420201433 }; static real_t tns_coef_1_4[] = { 0.0, 0.2079116908, 0.4067366431, 0.5877852523, -0.6736956436, -0.5264321629, -0.3612416662, -0.1837495178, 0.9945218954, 0.9510565163, 0.8660254038, 0.7431448255, -0.6736956436, -0.5264321629, -0.3612416662, -0.1837495178 }; #endif /* 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(ics, sr_index, object_type)); 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, min(tns_max_bands(ics, sr_index, object_type, frame_len), ics->max_sfb))]; end = ics->swb_offset[min(top, min(tns_max_bands(ics, sr_index, object_type, frame_len), 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(ics, sr_index, object_type)); 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, min(tns_max_bands(ics, sr_index, object_type, frame_len), ics->max_sfb))]; end = ics->swb_offset[min(top, min(tns_max_bands(ics, sr_index, object_type, frame_len), 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<m */ b[i] = a[i] + MUL_C_C(tmp2[m-1], a[m-i]); for (i = 1; i < m; i++) /* loop only while i<m */ a[i] = b[i]; a[m] = tmp2[m-1]; /* changed */ } } static void tns_ar_filter(real_t *spectrum, uint16_t size, int8_t inc, real_t *lpc, uint8_t order) { /* - Simple all-pole filter of order "order" defined by y(n) = x(n) - lpc[1]*y(n-1) - ... - lpc[order]*y(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] = 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] = 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; } } static uint8_t tns_max_bands_table[12][6] = { /* entry for each sampling rate * 1 Main/LC long window * 2 Main/LC short window * 3 SSR long window * 4 SSR short window * 5 LD 512 window * 6 LD 480 window */ { 31, 9, 28, 7, 0, 0 }, /* 96000 */ { 31, 9, 28, 7, 0, 0 }, /* 88200 */ { 34, 10, 27, 7, 0, 0 }, /* 64000 */ { 40, 14, 26, 6, 31, 31 }, /* 48000 */ { 42, 14, 26, 6, 32, 32 }, /* 44100 */ { 51, 14, 26, 6, 37, 37 }, /* 32000 */ { 46, 14, 29, 7, 31, 30 }, /* 24000 */ { 46, 14, 29, 7, 31, 30 }, /* 22050 */ { 42, 14, 23, 8, 0, 0 }, /* 16000 */ { 42, 14, 23, 8, 0, 0 }, /* 12000 */ { 42, 14, 23, 8, 0, 0 }, /* 11025 */ { 39, 14, 19, 7, 0, 0 }, /* 8000 */ }; static uint8_t tns_max_bands(ic_stream *ics, uint8_t sr_index, uint8_t object_type, uint16_t frame_len) { uint8_t i; i = (ics->window_sequence == EIGHT_SHORT_SEQUENCE) ? 1 : 0; #ifdef LD_DEC if (object_type == LD) { if (frame_len == 512) i = 4; else i = 5; } #endif return tns_max_bands_table[sr_index][i]; } static uint8_t tns_max_order(ic_stream *ics, uint8_t sr_index, uint8_t object_type) { /* Correction in 14496-3 Cor. 1 Works like MPEG2-AAC (13818-7) now For other object types (scalable) the following goes for tns max order for long windows: if (sr_index <= 5) return 12; else return 20; */ if (ics->window_sequence != EIGHT_SHORT_SEQUENCE) { switch (object_type) { case MAIN: case LTP: case ER_LTP: #ifdef LD_DEC case LD: #endif return 20; case LC: case ER_LC: case DRM_ER_LC: case SSR: return 12; } } else { return 7; } return 0; }