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
ff_acelp_update_past_gain(int16_t * quant_energy,int gain_corr_factor,int log2_ma_pred_order,int erasure)32 void 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
ff_acelp_decode_gain_code(AudioDSPContext * adsp,int gain_corr_factor,const int16_t * fc_v,int mr_energy,const int16_t * quant_energy,const int16_t * ma_prediction_coeff,int subframe_size,int ma_pred_order)53 int16_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
ff_amr_set_fixed_gain(float fixed_gain_factor,float fixed_mean_energy,float * prediction_error,float energy_mean,const float * pred_table)86 float 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
ff_decode_pitch_lag(int * lag_int,int * lag_frac,int pitch_index,const int prev_lag_int,const int subframe,int third_as_first,int resolution)107 void 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