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/internal.h"
26 #include "libavutil/libm.h"
27 #include "libavutil/mathematics.h"
29 #include "acelp_pitch_delay.h"
30 #include "celp_math.h"
33 int ff_acelp_decode_8bit_to_1st_delay3(int ac_index)
37 ac_index = 3 * ac_index - 510;
41 int ff_acelp_decode_4bit_to_2nd_delay3(
46 return 3 * (ac_index + pitch_delay_min);
47 else if(ac_index < 12)
48 return 3 * pitch_delay_min + ac_index + 6;
50 return 3 * (ac_index + pitch_delay_min) - 18;
53 int ff_acelp_decode_5_6_bit_to_2nd_delay3(
57 return 3 * pitch_delay_min + ac_index - 2;
60 int ff_acelp_decode_9bit_to_1st_delay6(int ac_index)
63 return ac_index + 105;
65 return 6 * (ac_index - 368);
67 int ff_acelp_decode_6bit_to_2nd_delay6(
71 return 6 * pitch_delay_min + ac_index - 3;
74 void ff_acelp_update_past_gain(
75 int16_t* quant_energy,
77 int log2_ma_pred_order,
81 int avg_gain=quant_energy[(1 << log2_ma_pred_order) - 1]; // (5.10)
83 for(i=(1 << log2_ma_pred_order) - 1; i>0; i--)
85 avg_gain += quant_energy[i-1];
86 quant_energy[i] = quant_energy[i-1];
90 quant_energy[0] = FFMAX(avg_gain >> log2_ma_pred_order, -10240) - 4096; // -10 and -4 in (5.10)
92 quant_energy[0] = (6165 * ((ff_log2_q15(gain_corr_factor) >> 2) - (13 << 13))) >> 13;
95 int16_t ff_acelp_decode_gain_code(
96 AudioDSPContext *adsp,
100 const int16_t* quant_energy,
101 const int16_t* ma_prediction_coeff,
109 for(i=0; i<ma_pred_order; i++)
110 mr_energy += quant_energy[i] * ma_prediction_coeff[i];
113 mr_energy += (((-6165LL * ff_log2(dsp->scalarproduct_int16(fc_v, fc_v, subframe_size, 0))) >> 3) & ~0x3ff);
115 mr_energy = (5439 * (mr_energy >> 15)) >> 8; // (0.15) = (0.15) * (7.23)
118 ((ff_exp2(mr_energy & 0x7fff) + 16) >> 5) * (gain_corr_factor >> 1),
119 (mr_energy >> 15) - 25
122 mr_energy = gain_corr_factor * exp(M_LN10 / (20 << 23) * mr_energy) /
123 sqrt(adsp->scalarproduct_int16(fc_v, fc_v, subframe_size));
124 return mr_energy >> 12;
128 float ff_amr_set_fixed_gain(float fixed_gain_factor, float fixed_mean_energy,
129 float *prediction_error, float energy_mean,
130 const float *pred_table)
133 // ^g_c = ^gamma_gc * 100.05 (predicted dB + mean dB - dB of fixed vector)
134 // Note 10^(0.05 * -10log(average x2)) = 1/sqrt((average x2)).
135 float val = fixed_gain_factor *
137 (avpriv_scalarproduct_float_c(pred_table, prediction_error, 4) +
139 sqrtf(fixed_mean_energy);
141 // update quantified prediction error energy history
142 memmove(&prediction_error[0], &prediction_error[1],
143 3 * sizeof(prediction_error[0]));
144 prediction_error[3] = 20.0 * log10f(fixed_gain_factor);
149 void ff_decode_pitch_lag(int *lag_int, int *lag_frac, int pitch_index,
150 const int prev_lag_int, const int subframe,
151 int third_as_first, int resolution)
153 /* Note n * 10923 >> 15 is floor(x/3) for 0 <= n <= 32767 */
154 if (subframe == 0 || (subframe == 2 && third_as_first)) {
156 if (pitch_index < 197)
159 pitch_index = 3 * pitch_index - 335;
162 if (resolution == 4) {
163 int search_range_min = av_clip(prev_lag_int - 5, PITCH_DELAY_MIN,
164 PITCH_DELAY_MAX - 9);
166 // decoding with 4-bit resolution
167 if (pitch_index < 4) {
168 // integer only precision for [search_range_min, search_range_min+3]
169 pitch_index = 3 * (pitch_index + search_range_min) + 1;
170 } else if (pitch_index < 12) {
171 // 1/3 fractional precision for [search_range_min+3 1/3, search_range_min+5 2/3]
172 pitch_index += 3 * search_range_min + 7;
174 // integer only precision for [search_range_min+6, search_range_min+9]
175 pitch_index = 3 * (pitch_index + search_range_min - 6) + 1;
178 // decoding with 5 or 6 bit resolution, 1/3 fractional precision
181 if (resolution == 5) {
182 pitch_index += 3 * av_clip(prev_lag_int - 10, PITCH_DELAY_MIN,
183 PITCH_DELAY_MAX - 19);
185 pitch_index += 3 * av_clip(prev_lag_int - 5, PITCH_DELAY_MIN,
186 PITCH_DELAY_MAX - 9);
189 *lag_int = pitch_index * 10923 >> 15;
190 *lag_frac = pitch_index - 3 * *lag_int - 1;