2 * gain code, gain pitch and pitch delay decoding
4 * Copyright (c) 2008 Vladimir Voroshilov
6 * This file is part of FFmpeg.
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.
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.
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
23 #include "libavutil/common.h"
24 #include "libavutil/float_dsp.h"
25 #include "libavutil/libm.h"
26 #include "libavutil/mathematics.h"
28 #include "acelp_pitch_delay.h"
29 #include "celp_math.h"
32 int ff_acelp_decode_8bit_to_1st_delay3(int ac_index
)
36 ac_index
= 3 * ac_index
- 510;
40 int ff_acelp_decode_4bit_to_2nd_delay3(
45 return 3 * (ac_index
+ pitch_delay_min
);
46 else if(ac_index
< 12)
47 return 3 * pitch_delay_min
+ ac_index
+ 6;
49 return 3 * (ac_index
+ pitch_delay_min
) - 18;
52 int ff_acelp_decode_5_6_bit_to_2nd_delay3(
56 return 3 * pitch_delay_min
+ ac_index
- 2;
59 int ff_acelp_decode_9bit_to_1st_delay6(int ac_index
)
62 return ac_index
+ 105;
64 return 6 * (ac_index
- 368);
66 int ff_acelp_decode_6bit_to_2nd_delay6(
70 return 6 * pitch_delay_min
+ ac_index
- 3;
73 void ff_acelp_update_past_gain(
74 int16_t* quant_energy
,
76 int log2_ma_pred_order
,
80 int avg_gain
=quant_energy
[(1 << log2_ma_pred_order
) - 1]; // (5.10)
82 for(i
=(1 << log2_ma_pred_order
) - 1; i
>0; i
--)
84 avg_gain
+= quant_energy
[i
-1];
85 quant_energy
[i
] = quant_energy
[i
-1];
89 quant_energy
[0] = FFMAX(avg_gain
>> log2_ma_pred_order
, -10240) - 4096; // -10 and -4 in (5.10)
91 quant_energy
[0] = (6165 * ((ff_log2_q15(gain_corr_factor
) >> 2) - (13 << 13))) >> 13;
94 int16_t ff_acelp_decode_gain_code(
95 AudioDSPContext
*adsp
,
99 const int16_t* quant_energy
,
100 const int16_t* ma_prediction_coeff
,
108 for(i
=0; i
<ma_pred_order
; i
++)
109 mr_energy
+= quant_energy
[i
] * ma_prediction_coeff
[i
];
112 mr_energy
+= (((-6165LL * ff_log2(dsp
->scalarproduct_int16(fc_v
, fc_v
, subframe_size
, 0))) >> 3) & ~0x3ff);
114 mr_energy
= (5439 * (mr_energy
>> 15)) >> 8; // (0.15) = (0.15) * (7.23)
117 ((ff_exp2(mr_energy
& 0x7fff) + 16) >> 5) * (gain_corr_factor
>> 1),
118 (mr_energy
>> 15) - 25
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;
127 float 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
)
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) +
138 sqrtf(fixed_mean_energy
);
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
);
148 void 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
)
152 /* Note n * 10923 >> 15 is floor(x/3) for 0 <= n <= 32767 */
153 if (subframe
== 0 || (subframe
== 2 && third_as_first
)) {
155 if (pitch_index
< 197)
158 pitch_index
= 3 * pitch_index
- 335;
161 if (resolution
== 4) {
162 int search_range_min
= av_clip(prev_lag_int
- 5, PITCH_DELAY_MIN
,
163 PITCH_DELAY_MAX
- 9);
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;
173 // integer only precision for [search_range_min+6, search_range_min+9]
174 pitch_index
= 3 * (pitch_index
+ search_range_min
- 6) + 1;
177 // decoding with 5 or 6 bit resolution, 1/3 fractional precision
180 if (resolution
== 5) {
181 pitch_index
+= 3 * av_clip(prev_lag_int
- 10, PITCH_DELAY_MIN
,
182 PITCH_DELAY_MAX
- 19);
184 pitch_index
+= 3 * av_clip(prev_lag_int
- 5, PITCH_DELAY_MIN
,
185 PITCH_DELAY_MAX
- 9);
188 *lag_int
= pitch_index
* 10923 >> 15;
189 *lag_frac
= pitch_index
- 3 * *lag_int
- 1;