x86: proresdsp: improve SIGNEXTEND macro comments
[ffmpeg.git] / libavcodec / acelp_pitch_delay.c
1 /*
2  * gain code, gain pitch and pitch delay decoding
3  *
4  * Copyright (c) 2008 Vladimir Voroshilov
5  *
6  * This file is part of Libav.
7  *
8  * Libav 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  * Libav 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 Libav; 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/mathematics.h"
24 #include "avcodec.h"
25 #include "dsputil.h"
26 #include "acelp_pitch_delay.h"
27 #include "celp_math.h"
28
29 int ff_acelp_decode_8bit_to_1st_delay3(int ac_index)
30 {
31     ac_index += 58;
32     if(ac_index > 254)
33         ac_index = 3 * ac_index - 510;
34     return ac_index;
35 }
36
37 int ff_acelp_decode_4bit_to_2nd_delay3(
38         int ac_index,
39         int pitch_delay_min)
40 {
41     if(ac_index < 4)
42         return 3 * (ac_index + pitch_delay_min);
43     else if(ac_index < 12)
44         return 3 * pitch_delay_min + ac_index + 6;
45     else
46         return 3 * (ac_index + pitch_delay_min) - 18;
47 }
48
49 int ff_acelp_decode_5_6_bit_to_2nd_delay3(
50         int ac_index,
51         int pitch_delay_min)
52 {
53         return 3 * pitch_delay_min + ac_index - 2;
54 }
55
56 int ff_acelp_decode_9bit_to_1st_delay6(int ac_index)
57 {
58     if(ac_index < 463)
59         return ac_index + 105;
60     else
61         return 6 * (ac_index - 368);
62 }
63 int ff_acelp_decode_6bit_to_2nd_delay6(
64         int ac_index,
65         int pitch_delay_min)
66 {
67     return 6 * pitch_delay_min + ac_index - 3;
68 }
69
70 void ff_acelp_update_past_gain(
71     int16_t* quant_energy,
72     int gain_corr_factor,
73     int log2_ma_pred_order,
74     int erasure)
75 {
76     int i;
77     int avg_gain=quant_energy[(1 << log2_ma_pred_order) - 1]; // (5.10)
78
79     for(i=(1 << log2_ma_pred_order) - 1; i>0; i--)
80     {
81         avg_gain       += quant_energy[i-1];
82         quant_energy[i] = quant_energy[i-1];
83     }
84
85     if(erasure)
86         quant_energy[0] = FFMAX(avg_gain >> log2_ma_pred_order, -10240) - 4096; // -10 and -4 in (5.10)
87     else
88         quant_energy[0] = (6165 * ((ff_log2(gain_corr_factor) >> 2) - (13 << 13))) >> 13;
89 }
90
91 int16_t ff_acelp_decode_gain_code(
92     DSPContext *dsp,
93     int gain_corr_factor,
94     const int16_t* fc_v,
95     int mr_energy,
96     const int16_t* quant_energy,
97     const int16_t* ma_prediction_coeff,
98     int subframe_size,
99     int ma_pred_order)
100 {
101     int i;
102
103     mr_energy <<= 10;
104
105     for(i=0; i<ma_pred_order; i++)
106         mr_energy += quant_energy[i] * ma_prediction_coeff[i];
107
108     mr_energy = gain_corr_factor * exp(M_LN10 / (20 << 23) * mr_energy) /
109                 sqrt(dsp->scalarproduct_int16(fc_v, fc_v, subframe_size));
110     return mr_energy >> 12;
111 }
112
113 float ff_amr_set_fixed_gain(float fixed_gain_factor, float fixed_mean_energy,
114                             float *prediction_error, float energy_mean,
115                             const float *pred_table)
116 {
117     // Equations 66-69:
118     // ^g_c = ^gamma_gc * 100.05 (predicted dB + mean dB - dB of fixed vector)
119     // Note 10^(0.05 * -10log(average x2)) = 1/sqrt((average x2)).
120     float val = fixed_gain_factor *
121         exp2f(M_LOG2_10 * 0.05 *
122               (ff_dot_productf(pred_table, prediction_error, 4) +
123                energy_mean)) /
124         sqrtf(fixed_mean_energy);
125
126     // update quantified prediction error energy history
127     memmove(&prediction_error[0], &prediction_error[1],
128             3 * sizeof(prediction_error[0]));
129     prediction_error[3] = 20.0 * log10f(fixed_gain_factor);
130
131     return val;
132 }
133
134 void ff_decode_pitch_lag(int *lag_int, int *lag_frac, int pitch_index,
135                          const int prev_lag_int, const int subframe,
136                          int third_as_first, int resolution)
137 {
138     /* Note n * 10923 >> 15 is floor(x/3) for 0 <= n <= 32767 */
139     if (subframe == 0 || (subframe == 2 && third_as_first)) {
140
141         if (pitch_index < 197)
142             pitch_index += 59;
143         else
144             pitch_index = 3 * pitch_index - 335;
145
146     } else {
147         if (resolution == 4) {
148             int search_range_min = av_clip(prev_lag_int - 5, PITCH_DELAY_MIN,
149                                            PITCH_DELAY_MAX - 9);
150
151             // decoding with 4-bit resolution
152             if (pitch_index < 4) {
153                 // integer only precision for [search_range_min, search_range_min+3]
154                 pitch_index = 3 * (pitch_index + search_range_min) + 1;
155             } else if (pitch_index < 12) {
156                 // 1/3 fractional precision for [search_range_min+3 1/3, search_range_min+5 2/3]
157                 pitch_index += 3 * search_range_min + 7;
158             } else {
159                 // integer only precision for [search_range_min+6, search_range_min+9]
160                 pitch_index = 3 * (pitch_index + search_range_min - 6) + 1;
161             }
162         } else {
163             // decoding with 5 or 6 bit resolution, 1/3 fractional precision
164             pitch_index--;
165
166             if (resolution == 5) {
167                 pitch_index += 3 * av_clip(prev_lag_int - 10, PITCH_DELAY_MIN,
168                                            PITCH_DELAY_MAX - 19);
169             } else
170                 pitch_index += 3 * av_clip(prev_lag_int - 5, PITCH_DELAY_MIN,
171                                            PITCH_DELAY_MAX - 9);
172         }
173     }
174     *lag_int  = pitch_index * 10923 >> 15;
175     *lag_frac = pitch_index - 3 * *lag_int - 1;
176 }