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/*
* gain code, gain pitch and pitch delay decoding
*
* Copyright (c) 2008 Vladimir Voroshilov
*
* This file is part of Libav.
*
* Libav is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public
* License as published by the Free Software Foundation; either
* version 2.1 of the License, or (at your option) any later version.
*
* Libav is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public
* License along with Libav; if not, write to the Free Software
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
*/
#include "libavutil/common.h"
#include "libavutil/mathematics.h"
#include "avcodec.h"
#include "dsputil.h"
#include "acelp_pitch_delay.h"
int ff_acelp_decode_8bit_to_1st_delay3(int ac_index)
{
ac_index += 58;
if(ac_index > 254)
ac_index = 3 * ac_index - 510;
return ac_index;
}
int ff_acelp_decode_4bit_to_2nd_delay3(
int ac_index,
int pitch_delay_min)
{
if(ac_index < 4)
return 3 * (ac_index + pitch_delay_min);
else if(ac_index < 12)
return 3 * pitch_delay_min + ac_index + 6;
else
return 3 * (ac_index + pitch_delay_min) - 18;
}
int ff_acelp_decode_5_6_bit_to_2nd_delay3(
int ac_index,
int pitch_delay_min)
{
return 3 * pitch_delay_min + ac_index - 2;
}
int ff_acelp_decode_9bit_to_1st_delay6(int ac_index)
{
if(ac_index < 463)
return ac_index + 105;
else
return 6 * (ac_index - 368);
}
int ff_acelp_decode_6bit_to_2nd_delay6(
int ac_index,
int pitch_delay_min)
{
return 6 * pitch_delay_min + ac_index - 3;
}
void ff_acelp_update_past_gain(
int16_t* quant_energy,
int gain_corr_factor,
int log2_ma_pred_order,
int erasure)
{
int i;
int avg_gain=quant_energy[(1 << log2_ma_pred_order) - 1]; // (5.10)
for(i=(1 << log2_ma_pred_order) - 1; i>0; i--)
{
avg_gain += quant_energy[i-1];
quant_energy[i] = quant_energy[i-1];
}
if(erasure)
quant_energy[0] = FFMAX(avg_gain >> log2_ma_pred_order, -10240) - 4096; // -10 and -4 in (5.10)
else
quant_energy[0] = (6165 * ((ff_log2(gain_corr_factor) >> 2) - (13 << 13))) >> 13;
}
int16_t ff_acelp_decode_gain_code(
DSPContext *dsp,
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)
{
int i;
mr_energy <<= 10;
for(i=0; i<ma_pred_order; i++)
mr_energy += quant_energy[i] * ma_prediction_coeff[i];
mr_energy = gain_corr_factor * exp(M_LN10 / (20 << 23) * mr_energy) /
sqrt(dsp->scalarproduct_int16(fc_v, fc_v, subframe_size));
return mr_energy >> 12;
}
float ff_amr_set_fixed_gain(float fixed_gain_factor, float fixed_mean_energy,
float *prediction_error, float energy_mean,
const float *pred_table)
{
// Equations 66-69:
// ^g_c = ^gamma_gc * 100.05 (predicted dB + mean dB - dB of fixed vector)
// Note 10^(0.05 * -10log(average x2)) = 1/sqrt((average x2)).
float val = fixed_gain_factor *
exp2f(M_LOG2_10 * 0.05 *
(ff_scalarproduct_float_c(pred_table, prediction_error, 4) +
energy_mean)) /
sqrtf(fixed_mean_energy);
// update quantified prediction error energy history
memmove(&prediction_error[0], &prediction_error[1],
3 * sizeof(prediction_error[0]));
prediction_error[3] = 20.0 * log10f(fixed_gain_factor);
return val;
}
void 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)
{
/* Note n * 10923 >> 15 is floor(x/3) for 0 <= n <= 32767 */
if (subframe == 0 || (subframe == 2 && third_as_first)) {
if (pitch_index < 197)
pitch_index += 59;
else
pitch_index = 3 * pitch_index - 335;
} else {
if (resolution == 4) {
int search_range_min = av_clip(prev_lag_int - 5, PITCH_DELAY_MIN,
PITCH_DELAY_MAX - 9);
// decoding with 4-bit resolution
if (pitch_index < 4) {
// integer only precision for [search_range_min, search_range_min+3]
pitch_index = 3 * (pitch_index + search_range_min) + 1;
} else if (pitch_index < 12) {
// 1/3 fractional precision for [search_range_min+3 1/3, search_range_min+5 2/3]
pitch_index += 3 * search_range_min + 7;
} else {
// integer only precision for [search_range_min+6, search_range_min+9]
pitch_index = 3 * (pitch_index + search_range_min - 6) + 1;
}
} else {
// decoding with 5 or 6 bit resolution, 1/3 fractional precision
pitch_index--;
if (resolution == 5) {
pitch_index += 3 * av_clip(prev_lag_int - 10, PITCH_DELAY_MIN,
PITCH_DELAY_MAX - 19);
} else
pitch_index += 3 * av_clip(prev_lag_int - 5, PITCH_DELAY_MIN,
PITCH_DELAY_MAX - 9);
}
}
*lag_int = pitch_index * 10923 >> 15;
*lag_frac = pitch_index - 3 * *lag_int - 1;
}
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