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/ffmath.h"
25#include "libavutil/float_dsp.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
32void ff_acelp_update_past_gain(
33    int16_t* quant_energy,
34    int gain_corr_factor,
35    int log2_ma_pred_order,
36    int erasure)
37{
38    int i;
39    int avg_gain=quant_energy[(1 << log2_ma_pred_order) - 1]; // (5.10)
40
41    for(i=(1 << log2_ma_pred_order) - 1; i>0; i--)
42    {
43        avg_gain       += quant_energy[i-1];
44        quant_energy[i] = quant_energy[i-1];
45    }
46
47    if(erasure)
48        quant_energy[0] = FFMAX(avg_gain >> log2_ma_pred_order, -10240) - 4096; // -10 and -4 in (5.10)
49    else
50        quant_energy[0] = (6165 * ((ff_log2_q15(gain_corr_factor) >> 2) - (13 << 13))) >> 13;
51}
52
53int16_t ff_acelp_decode_gain_code(
54    AudioDSPContext *adsp,
55    int gain_corr_factor,
56    const int16_t* fc_v,
57    int mr_energy,
58    const int16_t* quant_energy,
59    const int16_t* ma_prediction_coeff,
60    int subframe_size,
61    int ma_pred_order)
62{
63    int i;
64
65    mr_energy <<= 10;
66
67    for(i=0; i<ma_pred_order; i++)
68        mr_energy += quant_energy[i] * ma_prediction_coeff[i];
69
70#ifdef G729_BITEXACT
71    mr_energy += (((-6165LL * ff_log2(dsp->scalarproduct_int16(fc_v, fc_v, subframe_size, 0))) >> 3) & ~0x3ff);
72
73    mr_energy = (5439 * (mr_energy >> 15)) >> 8;           // (0.15) = (0.15) * (7.23)
74
75    return bidir_sal(
76               ((ff_exp2(mr_energy & 0x7fff) + 16) >> 5) * (gain_corr_factor >> 1),
77               (mr_energy >> 15) - 25
78           );
79#else
80    mr_energy = gain_corr_factor * ff_exp10((double)mr_energy / (20 << 23)) /
81                sqrt(adsp->scalarproduct_int16(fc_v, fc_v, subframe_size));
82    return mr_energy >> 12;
83#endif
84}
85
86float ff_amr_set_fixed_gain(float fixed_gain_factor, float fixed_mean_energy,
87                            float *prediction_error, float energy_mean,
88                            const float *pred_table)
89{
90    // Equations 66-69:
91    // ^g_c = ^gamma_gc * 100.05 (predicted dB + mean dB - dB of fixed vector)
92    // Note 10^(0.05 * -10log(average x2)) = 1/sqrt((average x2)).
93    float val = fixed_gain_factor *
94        ff_exp10(0.05 *
95              (avpriv_scalarproduct_float_c(pred_table, prediction_error, 4) +
96               energy_mean)) /
97        sqrtf(fixed_mean_energy ? fixed_mean_energy : 1.0);
98
99    // update quantified prediction error energy history
100    memmove(&prediction_error[0], &prediction_error[1],
101            3 * sizeof(prediction_error[0]));
102    prediction_error[3] = 20.0 * log10f(fixed_gain_factor);
103
104    return val;
105}
106
107void ff_decode_pitch_lag(int *lag_int, int *lag_frac, int pitch_index,
108                         const int prev_lag_int, const int subframe,
109                         int third_as_first, int resolution)
110{
111    /* Note n * 10923 >> 15 is floor(x/3) for 0 <= n <= 32767 */
112    if (subframe == 0 || (subframe == 2 && third_as_first)) {
113
114        if (pitch_index < 197)
115            pitch_index += 59;
116        else
117            pitch_index = 3 * pitch_index - 335;
118
119    } else {
120        if (resolution == 4) {
121            int search_range_min = av_clip(prev_lag_int - 5, PITCH_DELAY_MIN,
122                                           PITCH_DELAY_MAX - 9);
123
124            // decoding with 4-bit resolution
125            if (pitch_index < 4) {
126                // integer only precision for [search_range_min, search_range_min+3]
127                pitch_index = 3 * (pitch_index + search_range_min) + 1;
128            } else if (pitch_index < 12) {
129                // 1/3 fractional precision for [search_range_min+3 1/3, search_range_min+5 2/3]
130                pitch_index += 3 * search_range_min + 7;
131            } else {
132                // integer only precision for [search_range_min+6, search_range_min+9]
133                pitch_index = 3 * (pitch_index + search_range_min - 6) + 1;
134            }
135        } else {
136            // decoding with 5 or 6 bit resolution, 1/3 fractional precision
137            pitch_index--;
138
139            if (resolution == 5) {
140                pitch_index += 3 * av_clip(prev_lag_int - 10, PITCH_DELAY_MIN,
141                                           PITCH_DELAY_MAX - 19);
142            } else
143                pitch_index += 3 * av_clip(prev_lag_int - 5, PITCH_DELAY_MIN,
144                                           PITCH_DELAY_MAX - 9);
145        }
146    }
147    *lag_int  = pitch_index * 10923 >> 15;
148    *lag_frac = pitch_index - 3 * *lag_int - 1;
149}
150