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
25 #include "acelp_pitch_delay.h"
26 #include "celp_math.h"
28 int ff_acelp_decode_8bit_to_1st_delay3(int ac_index)
32 ac_index = 3 * ac_index - 510;
36 int ff_acelp_decode_4bit_to_2nd_delay3(
41 return 3 * (ac_index + pitch_delay_min);
42 else if(ac_index < 12)
43 return 3 * pitch_delay_min + ac_index + 6;
45 return 3 * (ac_index + pitch_delay_min) - 18;
48 int ff_acelp_decode_5_6_bit_to_2nd_delay3(
52 return 3 * pitch_delay_min + ac_index - 2;
55 int ff_acelp_decode_9bit_to_1st_delay6(int ac_index)
58 return ac_index + 105;
60 return 6 * (ac_index - 368);
62 int ff_acelp_decode_6bit_to_2nd_delay6(
66 return 6 * pitch_delay_min + ac_index - 3;
69 void ff_acelp_update_past_gain(
70 int16_t* quant_energy,
72 int log2_ma_pred_order,
76 int avg_gain=quant_energy[(1 << log2_ma_pred_order) - 1]; // (5.10)
78 for(i=(1 << log2_ma_pred_order) - 1; i>0; i--)
80 avg_gain += quant_energy[i-1];
81 quant_energy[i] = quant_energy[i-1];
85 quant_energy[0] = FFMAX(avg_gain >> log2_ma_pred_order, -10240) - 4096; // -10 and -4 in (5.10)
87 quant_energy[0] = (6165 * ((ff_log2(gain_corr_factor) >> 2) - (13 << 13))) >> 13;
90 int16_t ff_acelp_decode_gain_code(
95 const int16_t* quant_energy,
96 const int16_t* ma_prediction_coeff,
104 for(i=0; i<ma_pred_order; i++)
105 mr_energy += quant_energy[i] * ma_prediction_coeff[i];
108 mr_energy += (((-6165LL * ff_log2(dsp->scalarproduct_int16(fc_v, fc_v, subframe_size, 0))) >> 3) & ~0x3ff);
110 mr_energy = (5439 * (mr_energy >> 15)) >> 8; // (0.15) = (0.15) * (7.23)
113 ((ff_exp2(mr_energy & 0x7fff) + 16) >> 5) * (gain_corr_factor >> 1),
114 (mr_energy >> 15) - 25
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;
123 float 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)
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(log2f(10.0) * 0.05 *
132 (ff_dot_productf(pred_table, prediction_error, 4) +
134 sqrtf(fixed_mean_energy);
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);