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270 lines
9.0 KiB
270 lines
9.0 KiB
/*
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** FAAD2 - Freeware Advanced Audio (AAC) Decoder including SBR decoding
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** Copyright (C) 2003-2005 M. Bakker, Nero AG, http://www.nero.com
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**
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** This program is free software; you can redistribute it and/or modify
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** it under the terms of the GNU General Public License as published by
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** the Free Software Foundation; either version 2 of the License, or
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** (at your option) any later version.
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**
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** This program is distributed in the hope that it will be useful,
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** but WITHOUT ANY WARRANTY; without even the implied warranty of
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** MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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** GNU General Public License for more details.
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**
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** You should have received a copy of the GNU General Public License
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** along with this program; if not, write to the Free Software
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** Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
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**
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** Any non-GPL usage of this software or parts of this software is strictly
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** forbidden.
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**
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** The "appropriate copyright message" mentioned in section 2c of the GPLv2
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** must read: "Code from FAAD2 is copyright (c) Nero AG, www.nero.com"
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**
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** Commercial non-GPL licensing of this software is possible.
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** For more info contact Nero AG through Mpeg4AAClicense@nero.com.
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**
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** $Id: pns.c,v 1.39 2010/06/04 20:47:56 menno Exp $
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**/
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#include "common.h"
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#include "structs.h"
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#include "pns.h"
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/* static function declarations */
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static void gen_rand_vector(real_t *spec, int16_t scale_factor, uint16_t size,
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uint8_t sub,
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/* RNG states */ uint32_t *__r1, uint32_t *__r2);
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#ifdef FIXED_POINT
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static real_t const pow2_table[] =
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{
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COEF_CONST(1.0),
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COEF_CONST(1.18920711500272),
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COEF_CONST(1.41421356237310),
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COEF_CONST(1.68179283050743)
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};
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// mean_energy_table[x] == sqrt(3 / x)
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static real_t const mean_energy_table[] =
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{
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COEF_CONST(0.0), // should not happen
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COEF_CONST(1.7320508075688772),
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COEF_CONST(1.224744871391589),
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COEF_CONST(1.0), // sqrt(3/3)
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COEF_CONST(0.8660254037844386),
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COEF_CONST(0.7745966692414834),
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COEF_CONST(0.7071067811865476),
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COEF_CONST(0.6546536707079771),
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COEF_CONST(0.6123724356957945),
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COEF_CONST(0.5773502691896257),
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COEF_CONST(0.5477225575051661),
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COEF_CONST(0.5222329678670935),
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COEF_CONST(0.5), // sqrt(3/12)
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COEF_CONST(0.4803844614152614),
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COEF_CONST(0.4629100498862757),
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COEF_CONST(0.4472135954999579),
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};
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#endif
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/* The function gen_rand_vector(addr, size) generates a vector of length
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<size> with signed random values of average energy MEAN_NRG per random
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value. A suitable random number generator can be realized using one
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multiplication/accumulation per random value.
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*/
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static INLINE void gen_rand_vector(real_t *spec, int16_t scale_factor, uint16_t size,
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uint8_t sub,
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/* RNG states */ uint32_t *__r1, uint32_t *__r2)
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{
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#ifndef FIXED_POINT
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uint16_t i;
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real_t energy = 0.0;
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(void)sub;
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scale_factor = min(max(scale_factor, -120), 120);
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for (i = 0; i < size; i++)
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{
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real_t tmp = (real_t)(int32_t)ne_rng(__r1, __r2);
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spec[i] = tmp;
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energy += tmp*tmp;
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}
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if (energy > 0)
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{
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real_t scale = (real_t)1.0/(real_t)sqrt(energy);
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scale *= (real_t)pow(2.0, 0.25 * scale_factor);
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for (i = 0; i < size; i++)
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{
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spec[i] *= scale;
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}
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}
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#else
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uint16_t i;
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real_t scale;
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int32_t exp, frac;
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int32_t idx, mask;
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/* IMDCT pre-scaling */
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scale_factor -= 4 * sub;
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// 52 stands for 2**13 == 8192 factor; larger factor causes overflows later (in cfft).
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scale_factor = min(max(scale_factor, -(REAL_BITS * 4)), 52);
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exp = scale_factor >> 2;
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frac = scale_factor & 3;
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/* 29 <= REAL_BITS + exp <= 0 */
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mask = (1 << (REAL_BITS + exp)) - 1;
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idx = size;
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scale = COEF_CONST(1);
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// At most 2 iterations.
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while (idx >= 16)
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{
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idx >>= 2;
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scale >>= 1;
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}
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scale = MUL_C(scale, mean_energy_table[idx]);
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if (frac)
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scale = MUL_C(scale, pow2_table[frac]);
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// scale is less than 4.0 now.
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for (i = 0; i < size; i++)
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{
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real_t tmp = (int32_t)ne_rng(__r1, __r2);
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if (tmp < 0)
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tmp = -(tmp & mask);
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else
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tmp = (tmp & mask);
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spec[i] = MUL_C(tmp, scale);
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}
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#endif
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}
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void pns_decode(ic_stream *ics_left, ic_stream *ics_right,
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real_t *spec_left, real_t *spec_right, uint16_t frame_len,
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uint8_t channel_pair, uint8_t object_type,
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/* RNG states */ uint32_t *__r1, uint32_t *__r2)
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{
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uint8_t g, sfb, b;
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uint16_t begin, end;
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uint8_t group = 0;
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uint16_t nshort = frame_len >> 3;
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uint8_t sub = 0;
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#ifdef FIXED_POINT
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/* IMDCT scaling */
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if (object_type == LD)
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{
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sub = 9 /*9*/;
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} else {
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if (ics_left->window_sequence == EIGHT_SHORT_SEQUENCE)
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sub = 7 /*7*/;
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else
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sub = 10 /*10*/;
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}
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#else
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(void)object_type;
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#endif
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for (g = 0; g < ics_left->num_window_groups; g++)
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{
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/* Do perceptual noise substitution decoding */
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for (b = 0; b < ics_left->window_group_length[g]; b++)
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{
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uint16_t base = group * nshort;
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for (sfb = 0; sfb < ics_left->max_sfb; sfb++)
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{
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uint32_t r1_dep = 0, r2_dep = 0;
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if (is_noise(ics_left, g, sfb))
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{
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#ifdef LTP_DEC
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/* Simultaneous use of LTP and PNS is not prevented in the
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syntax. If both LTP, and PNS are enabled on the same
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scalefactor band, PNS takes precedence, and no prediction
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is applied to this band.
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*/
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ics_left->ltp.long_used[sfb] = 0;
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ics_left->ltp2.long_used[sfb] = 0;
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#endif
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#ifdef MAIN_DEC
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/* For scalefactor bands coded using PNS the corresponding
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predictors are switched to "off".
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*/
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ics_left->pred.prediction_used[sfb] = 0;
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#endif
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begin = min(base + ics_left->swb_offset[sfb], ics_left->swb_offset_max);
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end = min(base + ics_left->swb_offset[sfb+1], ics_left->swb_offset_max);
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r1_dep = *__r1;
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r2_dep = *__r2;
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/* Generate random vector */
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gen_rand_vector(&spec_left[begin],
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ics_left->scale_factors[g][sfb], end - begin, sub, __r1, __r2);
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}
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/* From the spec:
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If the same scalefactor band and group is coded by perceptual noise
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substitution in both channels of a channel pair, the correlation of
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the noise signal can be controlled by means of the ms_used field: While
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the default noise generation process works independently for each channel
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(separate generation of random vectors), the same random vector is used
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for both channels if ms_used[] is set for a particular scalefactor band
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and group. In this case, no M/S stereo coding is carried out (because M/S
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stereo coding and noise substitution coding are mutually exclusive).
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If the same scalefactor band and group is coded by perceptual noise
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substitution in only one channel of a channel pair the setting of ms_used[]
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is not evaluated.
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*/
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if ((ics_right != NULL)
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&& is_noise(ics_right, g, sfb))
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{
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#ifdef LTP_DEC
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/* See comment above. */
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ics_right->ltp.long_used[sfb] = 0;
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ics_right->ltp2.long_used[sfb] = 0;
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#endif
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#ifdef MAIN_DEC
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/* See comment above. */
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ics_right->pred.prediction_used[sfb] = 0;
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#endif
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if (channel_pair && is_noise(ics_left, g, sfb) &&
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(((ics_left->ms_mask_present == 1) &&
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(ics_left->ms_used[g][sfb])) ||
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(ics_left->ms_mask_present == 2)))
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{
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/*uint16_t c;*/
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begin = min(base + ics_right->swb_offset[sfb], ics_right->swb_offset_max);
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end = min(base + ics_right->swb_offset[sfb+1], ics_right->swb_offset_max);
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/* Generate random vector dependent on left channel*/
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gen_rand_vector(&spec_right[begin],
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ics_right->scale_factors[g][sfb], end - begin, sub, &r1_dep, &r2_dep);
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} else /*if (ics_left->ms_mask_present == 0)*/ {
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begin = min(base + ics_right->swb_offset[sfb], ics_right->swb_offset_max);
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end = min(base + ics_right->swb_offset[sfb+1], ics_right->swb_offset_max);
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/* Generate random vector */
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gen_rand_vector(&spec_right[begin],
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ics_right->scale_factors[g][sfb], end - begin, sub, __r1, __r2);
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}
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}
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} /* sfb */
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group++;
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} /* b */
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} /* g */
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}
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