1/*
2 * gain code, gain pitch and pitch delay decoding
3 *
4 * Copyright (c) 2008 Vladimir Voroshilov
5 *
6 * This file is part of FFmpeg.
7 *
8 * FFmpeg is free software; you can redistribute it and/or
9 * modify it under the terms of the GNU Lesser General Public
10 * License as published by the Free Software Foundation; either
11 * version 2.1 of the License, or (at your option) any later version.
12 *
13 * FFmpeg is distributed in the hope that it will be useful,
14 * but WITHOUT ANY WARRANTY; without even the implied warranty of
15 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
16 * Lesser General Public License for more details.
17 *
18 * You should have received a copy of the GNU Lesser General Public
19 * License along with FFmpeg; if not, write to the Free Software
20 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
21 */
22
23#include "libavutil/common.h"
24#include "libavutil/float_dsp.h"
25#include "libavutil/libm.h"
26#include "libavutil/mathematics.h"
27#include "avcodec.h"
28#include "acelp_pitch_delay.h"
29#include "celp_math.h"
30#include "audiodsp.h"
31
32int ff_acelp_decode_8bit_to_1st_delay3(int ac_index)
33{
34    ac_index += 58;
35    if(ac_index > 254)
36        ac_index = 3 * ac_index - 510;
37    return ac_index;
38}
39
40int ff_acelp_decode_4bit_to_2nd_delay3(
41        int ac_index,
42        int pitch_delay_min)
43{
44    if(ac_index < 4)
45        return 3 * (ac_index + pitch_delay_min);
46    else if(ac_index < 12)
47        return 3 * pitch_delay_min + ac_index + 6;
48    else
49        return 3 * (ac_index + pitch_delay_min) - 18;
50}
51
52int ff_acelp_decode_5_6_bit_to_2nd_delay3(
53        int ac_index,
54        int pitch_delay_min)
55{
56        return 3 * pitch_delay_min + ac_index - 2;
57}
58
59int ff_acelp_decode_9bit_to_1st_delay6(int ac_index)
60{
61    if(ac_index < 463)
62        return ac_index + 105;
63    else
64        return 6 * (ac_index - 368);
65}
66int ff_acelp_decode_6bit_to_2nd_delay6(
67        int ac_index,
68        int pitch_delay_min)
69{
70    return 6 * pitch_delay_min + ac_index - 3;
71}
72
73void ff_acelp_update_past_gain(
74    int16_t* quant_energy,
75    int gain_corr_factor,
76    int log2_ma_pred_order,
77    int erasure)
78{
79    int i;
80    int avg_gain=quant_energy[(1 << log2_ma_pred_order) - 1]; // (5.10)
81
82    for(i=(1 << log2_ma_pred_order) - 1; i>0; i--)
83    {
84        avg_gain       += quant_energy[i-1];
85        quant_energy[i] = quant_energy[i-1];
86    }
87
88    if(erasure)
89        quant_energy[0] = FFMAX(avg_gain >> log2_ma_pred_order, -10240) - 4096; // -10 and -4 in (5.10)
90    else
91        quant_energy[0] = (6165 * ((ff_log2_q15(gain_corr_factor) >> 2) - (13 << 13))) >> 13;
92}
93
94int16_t ff_acelp_decode_gain_code(
95    AudioDSPContext *adsp,
96    int gain_corr_factor,
97    const int16_t* fc_v,
98    int mr_energy,
99    const int16_t* quant_energy,
100    const int16_t* ma_prediction_coeff,
101    int subframe_size,
102    int ma_pred_order)
103{
104    int i;
105
106    mr_energy <<= 10;
107
108    for(i=0; i<ma_pred_order; i++)
109        mr_energy += quant_energy[i] * ma_prediction_coeff[i];
110
111#ifdef G729_BITEXACT
112    mr_energy += (((-6165LL * ff_log2(dsp->scalarproduct_int16(fc_v, fc_v, subframe_size, 0))) >> 3) & ~0x3ff);
113
114    mr_energy = (5439 * (mr_energy >> 15)) >> 8;           // (0.15) = (0.15) * (7.23)
115
116    return bidir_sal(
117               ((ff_exp2(mr_energy & 0x7fff) + 16) >> 5) * (gain_corr_factor >> 1),
118               (mr_energy >> 15) - 25
119           );
120#else
121    mr_energy = gain_corr_factor * exp(M_LN10 / (20 << 23) * mr_energy) /
122                sqrt(adsp->scalarproduct_int16(fc_v, fc_v, subframe_size));
123    return mr_energy >> 12;
124#endif
125}
126
127float ff_amr_set_fixed_gain(float fixed_gain_factor, float fixed_mean_energy,
128                            float *prediction_error, float energy_mean,
129                            const float *pred_table)
130{
131    // Equations 66-69:
132    // ^g_c = ^gamma_gc * 100.05 (predicted dB + mean dB - dB of fixed vector)
133    // Note 10^(0.05 * -10log(average x2)) = 1/sqrt((average x2)).
134    float val = fixed_gain_factor *
135        exp2f(M_LOG2_10 * 0.05 *
136              (avpriv_scalarproduct_float_c(pred_table, prediction_error, 4) +
137               energy_mean)) /
138        sqrtf(fixed_mean_energy);
139
140    // update quantified prediction error energy history
141    memmove(&prediction_error[0], &prediction_error[1],
142            3 * sizeof(prediction_error[0]));
143    prediction_error[3] = 20.0 * log10f(fixed_gain_factor);
144
145    return val;
146}
147
148void ff_decode_pitch_lag(int *lag_int, int *lag_frac, int pitch_index,
149                         const int prev_lag_int, const int subframe,
150                         int third_as_first, int resolution)
151{
152    /* Note n * 10923 >> 15 is floor(x/3) for 0 <= n <= 32767 */
153    if (subframe == 0 || (subframe == 2 && third_as_first)) {
154
155        if (pitch_index < 197)
156            pitch_index += 59;
157        else
158            pitch_index = 3 * pitch_index - 335;
159
160    } else {
161        if (resolution == 4) {
162            int search_range_min = av_clip(prev_lag_int - 5, PITCH_DELAY_MIN,
163                                           PITCH_DELAY_MAX - 9);
164
165            // decoding with 4-bit resolution
166            if (pitch_index < 4) {
167                // integer only precision for [search_range_min, search_range_min+3]
168                pitch_index = 3 * (pitch_index + search_range_min) + 1;
169            } else if (pitch_index < 12) {
170                // 1/3 fractional precision for [search_range_min+3 1/3, search_range_min+5 2/3]
171                pitch_index += 3 * search_range_min + 7;
172            } else {
173                // integer only precision for [search_range_min+6, search_range_min+9]
174                pitch_index = 3 * (pitch_index + search_range_min - 6) + 1;
175            }
176        } else {
177            // decoding with 5 or 6 bit resolution, 1/3 fractional precision
178            pitch_index--;
179
180            if (resolution == 5) {
181                pitch_index += 3 * av_clip(prev_lag_int - 10, PITCH_DELAY_MIN,
182                                           PITCH_DELAY_MAX - 19);
183            } else
184                pitch_index += 3 * av_clip(prev_lag_int - 5, PITCH_DELAY_MIN,
185                                           PITCH_DELAY_MAX - 9);
186        }
187    }
188    *lag_int  = pitch_index * 10923 >> 15;
189    *lag_frac = pitch_index - 3 * *lag_int - 1;
190}
191