aboutsummaryrefslogtreecommitdiffhomepage
path: root/libfaad2/lt_predict.c
blob: 835c5de210752f5a12b2793663a1b91f82e39c66 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
/*
** FAAD2 - Freeware Advanced Audio (AAC) Decoder including SBR decoding
** Copyright (C) 2003-2004 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: lt_predict.c,v 1.23 2004/09/04 14:56:28 menno Exp $
**/


#include "common.h"
#include "structs.h"

#ifdef LTP_DEC

#include <stdlib.h>
#include "syntax.h"
#include "lt_predict.h"
#include "filtbank.h"
#include "tns.h"


/* static function declarations */
static int16_t real_to_int16(real_t sig_in);


/* check if the object type is an object type that can have LTP */
uint8_t is_ltp_ot(uint8_t object_type)
{
#ifdef LTP_DEC
    if ((object_type == LTP)
#ifdef ERROR_RESILIENCE
        || (object_type == ER_LTP)
#endif
#ifdef LD_DEC
        || (object_type == LD)
#endif
#ifdef SCALABLE_DEC
        || (object_type == 6) /* TODO */
#endif
        )
    {
        return 1;
    }
#endif

    return 0;
}

ALIGN static const real_t codebook[8] =
{
    REAL_CONST(0.570829),
    REAL_CONST(0.696616),
    REAL_CONST(0.813004),
    REAL_CONST(0.911304),
    REAL_CONST(0.984900),
    REAL_CONST(1.067894),
    REAL_CONST(1.194601),
    REAL_CONST(1.369533)
};

void lt_prediction(ic_stream *ics, ltp_info *ltp, real_t *spec,
                   int16_t *lt_pred_stat, fb_info *fb, uint8_t win_shape,
                   uint8_t win_shape_prev, uint8_t sr_index,
                   uint8_t object_type, uint16_t frame_len)
{
    uint8_t sfb;
    uint16_t bin, i, num_samples;
    ALIGN real_t x_est[2048];
    ALIGN real_t X_est[2048];

    if (ics->window_sequence != EIGHT_SHORT_SEQUENCE)
    {
        if (ltp->data_present)
        {
            num_samples = frame_len << 1;

            for(i = 0; i < num_samples; i++)
            {
                /* The extra lookback M (N/2 for LD, 0 for LTP) is handled
                   in the buffer updating */

#if 0
                x_est[i] = MUL_R_C(lt_pred_stat[num_samples + i - ltp->lag],
                    codebook[ltp->coef]);
#else
                /* lt_pred_stat is a 16 bit int, multiplied with the fixed point real
                   this gives a real for x_est
                */
                x_est[i] = (real_t)lt_pred_stat[num_samples + i - ltp->lag] * codebook[ltp->coef];
#endif
            }

            filter_bank_ltp(fb, ics->window_sequence, win_shape, win_shape_prev,
                x_est, X_est, object_type, frame_len);

            tns_encode_frame(ics, &(ics->tns), sr_index, object_type, X_est,
                frame_len);

            for (sfb = 0; sfb < ltp->last_band; sfb++)
            {
                if (ltp->long_used[sfb])
                {
                    uint16_t low  = ics->swb_offset[sfb];
                    uint16_t high = ics->swb_offset[sfb+1];

                    for (bin = low; bin < high; bin++)
                    {
                        spec[bin] += X_est[bin];
                    }
                }
            }
        }
    }
}

#ifdef FIXED_POINT
static INLINE int16_t real_to_int16(real_t sig_in)
{
    if (sig_in >= 0)
    {
        sig_in += (1 << (REAL_BITS-1));
        if (sig_in >= REAL_CONST(32768))
            return 32767;
    } else {
        sig_in += -(1 << (REAL_BITS-1));
        if (sig_in <= REAL_CONST(-32768))
            return -32768;
    }

    return (sig_in >> REAL_BITS);
}
#else
static INLINE int16_t real_to_int16(real_t sig_in)
{
    if (sig_in >= 0)
    {
#ifndef HAS_LRINTF
        sig_in += 0.5f;
#endif
        if (sig_in >= 32768.0f)
            return 32767;
    } else {
#ifndef HAS_LRINTF
        sig_in += -0.5f;
#endif
        if (sig_in <= -32768.0f)
            return -32768;
    }

    return lrintf(sig_in);
}
#endif

void lt_update_state(int16_t *lt_pred_stat, real_t *time, real_t *overlap,
                     uint16_t frame_len, uint8_t object_type)
{
    uint16_t i;

    /*
     * The reference point for index i and the content of the buffer
     * lt_pred_stat are arranged so that lt_pred_stat(0 ... N/2 - 1) contains the
     * last aliased half window from the IMDCT, and lt_pred_stat(N/2 ... N-1)
     * is always all zeros. The rest of lt_pred_stat (i<0) contains the previous
     * fully reconstructed time domain samples, i.e., output of the decoder.
     *
     * These values are shifted up by N*2 to avoid (i<0)
     *
     * For the LD object type an extra 512 samples lookback is accomodated here.
     */
#ifdef LD_DEC
    if (object_type == LD)
    {
        for (i = 0; i < frame_len; i++)
        {
            lt_pred_stat[i]  /* extra 512 */  = lt_pred_stat[i + frame_len];
            lt_pred_stat[frame_len + i]       = lt_pred_stat[i + (frame_len * 2)];
            lt_pred_stat[(frame_len * 2) + i] = real_to_int16(time[i]);
            lt_pred_stat[(frame_len * 3) + i] = real_to_int16(overlap[i]);
        }
    } else {
#endif
        for (i = 0; i < frame_len; i++)
        {
            lt_pred_stat[i]                   = lt_pred_stat[i + frame_len];
            lt_pred_stat[frame_len + i]       = real_to_int16(time[i]);
            lt_pred_stat[(frame_len * 2) + i] = real_to_int16(overlap[i]);
#if 0 /* set to zero once upon initialisation */
            lt_pred_stat[(frame_len * 3) + i] = 0;
#endif
        }
#ifdef LD_DEC
    }
#endif
}

#endif