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Diffstat (limited to 'faad2/src/libfaad/pns.c')
| -rw-r--r-- | faad2/src/libfaad/pns.c | 271 |
1 files changed, 271 insertions, 0 deletions
diff --git a/faad2/src/libfaad/pns.c b/faad2/src/libfaad/pns.c new file mode 100644 index 0000000..fad9800 --- /dev/null +++ b/faad2/src/libfaad/pns.c @@ -0,0 +1,271 @@ +/*
+** FAAD2 - Freeware Advanced Audio (AAC) Decoder including SBR decoding
+** Copyright (C) 2003-2005 M. Bakker, Nero 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.
+**
+** The "appropriate copyright message" mentioned in section 2c of the GPLv2
+** must read: "Code from FAAD2 is copyright (c) Nero AG, www.nero.com"
+**
+** Commercial non-GPL licensing of this software is possible.
+** For more info contact Nero AG through Mpeg4AAClicense@nero.com.
+**
+** $Id: pns.c,v 1.38 2007/11/01 12:33:32 menno Exp $
+**/
+
+#include "common.h"
+#include "structs.h"
+
+#include "pns.h"
+
+
+/* static function declarations */
+static void gen_rand_vector(real_t *spec, int16_t scale_factor, uint16_t size,
+ uint8_t sub,
+ /* RNG states */ uint32_t *__r1, uint32_t *__r2);
+
+
+#ifdef FIXED_POINT
+
+#define DIV(A, B) (((int64_t)A << REAL_BITS)/B)
+
+#define step(shift) \
+ if ((0x40000000l >> shift) + root <= value) \
+ { \
+ value -= (0x40000000l >> shift) + root; \
+ root = (root >> 1) | (0x40000000l >> shift); \
+ } else { \
+ root = root >> 1; \
+ }
+
+/* fixed point square root approximation */
+/* !!!! ONLY WORKS FOR EVEN %REAL_BITS% !!!! */
+real_t fp_sqrt(real_t value)
+{
+ real_t root = 0;
+
+ step( 0); step( 2); step( 4); step( 6);
+ step( 8); step(10); step(12); step(14);
+ step(16); step(18); step(20); step(22);
+ step(24); step(26); step(28); step(30);
+
+ if (root < value)
+ ++root;
+
+ root <<= (REAL_BITS/2);
+
+ return root;
+}
+
+static real_t const pow2_table[] =
+{
+ COEF_CONST(1.0),
+ COEF_CONST(1.18920711500272),
+ COEF_CONST(1.41421356237310),
+ COEF_CONST(1.68179283050743)
+};
+#endif
+
+/* The function gen_rand_vector(addr, size) generates a vector of length
+ <size> with signed random values of average energy MEAN_NRG per random
+ value. A suitable random number generator can be realized using one
+ multiplication/accumulation per random value.
+*/
+static INLINE void gen_rand_vector(real_t *spec, int16_t scale_factor, uint16_t size,
+ uint8_t sub,
+ /* RNG states */ uint32_t *__r1, uint32_t *__r2)
+{
+#ifndef FIXED_POINT
+ uint16_t i;
+ real_t energy = 0.0;
+
+ real_t scale = (real_t)1.0/(real_t)size;
+
+ for (i = 0; i < size; i++)
+ {
+ real_t tmp = scale*(real_t)(int32_t)ne_rng(__r1, __r2);
+ spec[i] = tmp;
+ energy += tmp*tmp;
+ }
+
+ scale = (real_t)1.0/(real_t)sqrt(energy);
+ scale *= (real_t)pow(2.0, 0.25 * scale_factor);
+ for (i = 0; i < size; i++)
+ {
+ spec[i] *= scale;
+ }
+#else
+ uint16_t i;
+ real_t energy = 0, scale;
+ int32_t exp, frac;
+
+ for (i = 0; i < size; i++)
+ {
+ /* this can be replaced by a 16 bit random generator!!!! */
+ real_t tmp = (int32_t)ne_rng(__r1, __r2);
+ if (tmp < 0)
+ tmp = -(tmp & ((1<<(REAL_BITS-1))-1));
+ else
+ tmp = (tmp & ((1<<(REAL_BITS-1))-1));
+
+ energy += MUL_R(tmp,tmp);
+
+ spec[i] = tmp;
+ }
+
+ energy = fp_sqrt(energy);
+ if (energy > 0)
+ {
+ scale = DIV(REAL_CONST(1),energy);
+
+ exp = scale_factor >> 2;
+ frac = scale_factor & 3;
+
+ /* IMDCT pre-scaling */
+ exp -= sub;
+
+ if (exp < 0)
+ scale >>= -exp;
+ else
+ scale <<= exp;
+
+ if (frac)
+ scale = MUL_C(scale, pow2_table[frac]);
+
+ for (i = 0; i < size; i++)
+ {
+ spec[i] = MUL_R(spec[i], scale);
+ }
+ }
+#endif
+}
+
+void pns_decode(ic_stream *ics_left, ic_stream *ics_right,
+ real_t *spec_left, real_t *spec_right, uint16_t frame_len,
+ uint8_t channel_pair, uint8_t object_type,
+ /* RNG states */ uint32_t *__r1, uint32_t *__r2)
+{
+ uint8_t g, sfb, b;
+ uint16_t size, offs;
+
+ uint8_t group = 0;
+ uint16_t nshort = frame_len >> 3;
+
+ uint8_t sub = 0;
+
+#ifdef FIXED_POINT
+ /* IMDCT scaling */
+ if (object_type == LD)
+ {
+ sub = 9 /*9*/;
+ } else {
+ if (ics_left->window_sequence == EIGHT_SHORT_SEQUENCE)
+ sub = 7 /*7*/;
+ else
+ sub = 10 /*10*/;
+ }
+#endif
+
+ for (g = 0; g < ics_left->num_window_groups; g++)
+ {
+ /* Do perceptual noise substitution decoding */
+ for (b = 0; b < ics_left->window_group_length[g]; b++)
+ {
+ for (sfb = 0; sfb < ics_left->max_sfb; sfb++)
+ {
+ if (is_noise(ics_left, g, sfb))
+ {
+#ifdef LTP_DEC
+ /* Simultaneous use of LTP and PNS is not prevented in the
+ syntax. If both LTP, and PNS are enabled on the same
+ scalefactor band, PNS takes precedence, and no prediction
+ is applied to this band.
+ */
+ ics_left->ltp.long_used[sfb] = 0;
+ ics_left->ltp2.long_used[sfb] = 0;
+#endif
+
+#ifdef MAIN_DEC
+ /* For scalefactor bands coded using PNS the corresponding
+ predictors are switched to "off".
+ */
+ ics_left->pred.prediction_used[sfb] = 0;
+#endif
+
+ offs = ics_left->swb_offset[sfb];
+ size = min(ics_left->swb_offset[sfb+1], ics_left->swb_offset_max) - offs;
+
+ /* Generate random vector */
+ gen_rand_vector(&spec_left[(group*nshort)+offs],
+ ics_left->scale_factors[g][sfb], size, sub, __r1, __r2);
+ }
+
+/* From the spec:
+ If the same scalefactor band and group is coded by perceptual noise
+ substitution in both channels of a channel pair, the correlation of
+ the noise signal can be controlled by means of the ms_used field: While
+ the default noise generation process works independently for each channel
+ (separate generation of random vectors), the same random vector is used
+ for both channels if ms_used[] is set for a particular scalefactor band
+ and group. In this case, no M/S stereo coding is carried out (because M/S
+ stereo coding and noise substitution coding are mutually exclusive).
+ If the same scalefactor band and group is coded by perceptual noise
+ substitution in only one channel of a channel pair the setting of ms_used[]
+ is not evaluated.
+*/
+ if (channel_pair)
+ {
+ if (is_noise(ics_right, g, sfb))
+ {
+ if (((ics_left->ms_mask_present == 1) &&
+ (ics_left->ms_used[g][sfb])) ||
+ (ics_left->ms_mask_present == 2))
+ {
+ uint16_t c;
+
+ offs = ics_right->swb_offset[sfb];
+ size = min(ics_right->swb_offset[sfb+1], ics_right->swb_offset_max) - offs;
+
+ for (c = 0; c < size; c++)
+ {
+ spec_right[(group*nshort) + offs + c] =
+ spec_left[(group*nshort) + offs + c];
+ }
+ } else /*if (ics_left->ms_mask_present == 0)*/ {
+#ifdef LTP_DEC
+ ics_right->ltp.long_used[sfb] = 0;
+ ics_right->ltp2.long_used[sfb] = 0;
+#endif
+#ifdef MAIN_DEC
+ ics_right->pred.prediction_used[sfb] = 0;
+#endif
+
+ offs = ics_right->swb_offset[sfb];
+ size = min(ics_right->swb_offset[sfb+1], ics_right->swb_offset_max) - offs;
+
+ /* Generate random vector */
+ gen_rand_vector(&spec_right[(group*nshort)+offs],
+ ics_right->scale_factors[g][sfb], size, sub, __r1, __r2);
+ }
+ }
+ }
+ } /* sfb */
+ group++;
+ } /* b */
+ } /* g */
+}
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