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 "avcodec.h"
24#include "dsputil.h"
25#include "acelp_pitch_delay.h"
26#include "celp_math.h"
27
28int ff_acelp_decode_8bit_to_1st_delay3(int ac_index)
29{
30    ac_index += 58;
31    if(ac_index > 254)
32        ac_index = 3 * ac_index - 510;
33    return ac_index;
34}
35
36int ff_acelp_decode_4bit_to_2nd_delay3(
37        int ac_index,
38        int pitch_delay_min)
39{
40    if(ac_index < 4)
41        return 3 * (ac_index + pitch_delay_min);
42    else if(ac_index < 12)
43        return 3 * pitch_delay_min + ac_index + 6;
44    else
45        return 3 * (ac_index + pitch_delay_min) - 18;
46}
47
48int ff_acelp_decode_5_6_bit_to_2nd_delay3(
49        int ac_index,
50        int pitch_delay_min)
51{
52        return 3 * pitch_delay_min + ac_index - 2;
53}
54
55int ff_acelp_decode_9bit_to_1st_delay6(int ac_index)
56{
57    if(ac_index < 463)
58        return ac_index + 105;
59    else
60        return 6 * (ac_index - 368);
61}
62int ff_acelp_decode_6bit_to_2nd_delay6(
63        int ac_index,
64        int pitch_delay_min)
65{
66    return 6 * pitch_delay_min + ac_index - 3;
67}
68
69void ff_acelp_update_past_gain(
70    int16_t* quant_energy,
71    int gain_corr_factor,
72    int log2_ma_pred_order,
73    int erasure)
74{
75    int i;
76    int avg_gain=quant_energy[(1 << log2_ma_pred_order) - 1]; // (5.10)
77
78    for(i=(1 << log2_ma_pred_order) - 1; i>0; i--)
79    {
80        avg_gain       += quant_energy[i-1];
81        quant_energy[i] = quant_energy[i-1];
82    }
83
84    if(erasure)
85        quant_energy[0] = FFMAX(avg_gain >> log2_ma_pred_order, -10240) - 4096; // -10 and -4 in (5.10)
86    else
87        quant_energy[0] = (6165 * ((ff_log2(gain_corr_factor) >> 2) - (13 << 13))) >> 13;
88}
89
90int16_t ff_acelp_decode_gain_code(
91    DSPContext *dsp,
92    int gain_corr_factor,
93    const int16_t* fc_v,
94    int mr_energy,
95    const int16_t* quant_energy,
96    const int16_t* ma_prediction_coeff,
97    int subframe_size,
98    int ma_pred_order)
99{
100    int i;
101
102    mr_energy <<= 10;
103
104    for(i=0; i<ma_pred_order; i++)
105        mr_energy += quant_energy[i] * ma_prediction_coeff[i];
106
107#ifdef G729_BITEXACT
108    mr_energy += (((-6165LL * ff_log2(dsp->scalarproduct_int16(fc_v, fc_v, subframe_size, 0))) >> 3) & ~0x3ff);
109
110    mr_energy = (5439 * (mr_energy >> 15)) >> 8;           // (0.15) = (0.15) * (7.23)
111
112    return bidir_sal(
113               ((ff_exp2(mr_energy & 0x7fff) + 16) >> 5) * (gain_corr_factor >> 1),
114               (mr_energy >> 15) - 25
115           );
116#else
117    mr_energy = gain_corr_factor * exp(M_LN10 / (20 << 23) * mr_energy) /
118                sqrt(dsp->scalarproduct_int16(fc_v, fc_v, subframe_size, 0));
119    return mr_energy >> 12;
120#endif
121}
122
123float ff_amr_set_fixed_gain(float fixed_gain_factor, float fixed_mean_energy,
124                            float *prediction_error, float energy_mean,
125                            const float *pred_table)
126{
127    // Equations 66-69:
128    // ^g_c = ^gamma_gc * 100.05 (predicted dB + mean dB - dB of fixed vector)
129    // Note 10^(0.05 * -10log(average x2)) = 1/sqrt((average x2)).
130    float val = fixed_gain_factor *
131        exp2f(M_LOG2_10 * 0.05 *
132              (ff_dot_productf(pred_table, prediction_error, 4) +
133               energy_mean)) /
134        sqrtf(fixed_mean_energy);
135
136    // update quantified prediction error energy history
137    memmove(&prediction_error[0], &prediction_error[1],
138            3 * sizeof(prediction_error[0]));
139    prediction_error[3] = 20.0 * log10f(fixed_gain_factor);
140
141    return val;
142}
143
144void ff_decode_pitch_lag(int *lag_int, int *lag_frac, int pitch_index,
145                         const int prev_lag_int, const int subframe,
146                         int third_as_first, int resolution)
147{
148    /* Note n * 10923 >> 15 is floor(x/3) for 0 <= n <= 32767 */
149    if (subframe == 0 || (subframe == 2 && third_as_first)) {
150
151        if (pitch_index < 197)
152            pitch_index += 59;
153        else
154            pitch_index = 3 * pitch_index - 335;
155
156    } else {
157        if (resolution == 4) {
158            int search_range_min = av_clip(prev_lag_int - 5, PITCH_DELAY_MIN,
159                                           PITCH_DELAY_MAX - 9);
160
161            // decoding with 4-bit resolution
162            if (pitch_index < 4) {
163                // integer only precision for [search_range_min, search_range_min+3]
164                pitch_index = 3 * (pitch_index + search_range_min) + 1;
165            } else if (pitch_index < 12) {
166                // 1/3 fractional precision for [search_range_min+3 1/3, search_range_min+5 2/3]
167                pitch_index += 3 * search_range_min + 7;
168            } else {
169                // integer only precision for [search_range_min+6, search_range_min+9]
170                pitch_index = 3 * (pitch_index + search_range_min - 6) + 1;
171            }
172        } else {
173            // decoding with 5 or 6 bit resolution, 1/3 fractional precision
174            pitch_index--;
175
176            if (resolution == 5) {
177                pitch_index += 3 * av_clip(prev_lag_int - 10, PITCH_DELAY_MIN,
178                                           PITCH_DELAY_MAX - 19);
179            } else
180                pitch_index += 3 * av_clip(prev_lag_int - 5, PITCH_DELAY_MIN,
181                                           PITCH_DELAY_MAX - 9);
182        }
183    }
184    *lag_int  = pitch_index * 10923 >> 15;
185    *lag_frac = pitch_index - 3 * *lag_int - 1;
186}
187