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/* |
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* gain code, gain pitch and pitch delay decoding |
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* |
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* Copyright (c) 2008 Vladimir Voroshilov |
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* |
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* This file is part of FFmpeg. |
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* |
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* FFmpeg is free software; you can redistribute it and/or |
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* modify it under the terms of the GNU Lesser General Public |
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* License as published by the Free Software Foundation; either |
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* version 2.1 of the License, or (at your option) any later version. |
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* |
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* FFmpeg is distributed in the hope that it will be useful, |
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* but WITHOUT ANY WARRANTY; without even the implied warranty of |
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU |
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* Lesser General Public License for more details. |
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* |
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* You should have received a copy of the GNU Lesser General Public |
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* License along with FFmpeg; if not, write to the Free Software |
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* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA |
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*/ |
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#include "libavutil/common.h" |
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#include "libavutil/ffmath.h" |
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#include "libavutil/float_dsp.h" |
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#include "libavutil/mathematics.h" |
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#include "avcodec.h" |
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#include "acelp_pitch_delay.h" |
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#include "celp_math.h" |
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#include "audiodsp.h" |
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void ff_acelp_update_past_gain( |
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int16_t* quant_energy, |
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int gain_corr_factor, |
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int log2_ma_pred_order, |
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int erasure) |
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{ |
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int i; |
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int avg_gain=quant_energy[(1 << log2_ma_pred_order) - 1]; // (5.10) |
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for(i=(1 << log2_ma_pred_order) - 1; i>0; i--) |
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{ |
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avg_gain += quant_energy[i-1]; |
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quant_energy[i] = quant_energy[i-1]; |
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} |
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if(erasure) |
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quant_energy[0] = FFMAX(avg_gain >> log2_ma_pred_order, -10240) - 4096; // -10 and -4 in (5.10) |
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else |
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quant_energy[0] = (6165 * ((ff_log2_q15(gain_corr_factor) >> 2) - (13 << 13))) >> 13; |
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} |
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int16_t ff_acelp_decode_gain_code( |
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AudioDSPContext *adsp, |
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int gain_corr_factor, |
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const int16_t* fc_v, |
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int mr_energy, |
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const int16_t* quant_energy, |
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const int16_t* ma_prediction_coeff, |
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int subframe_size, |
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int ma_pred_order) |
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{ |
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int i; |
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mr_energy <<= 10; |
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for(i=0; i<ma_pred_order; i++) |
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mr_energy += quant_energy[i] * ma_prediction_coeff[i]; |
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#ifdef G729_BITEXACT |
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mr_energy += (((-6165LL * ff_log2(dsp->scalarproduct_int16(fc_v, fc_v, subframe_size, 0))) >> 3) & ~0x3ff); |
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mr_energy = (5439 * (mr_energy >> 15)) >> 8; // (0.15) = (0.15) * (7.23) |
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return bidir_sal( |
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((ff_exp2(mr_energy & 0x7fff) + 16) >> 5) * (gain_corr_factor >> 1), |
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(mr_energy >> 15) - 25 |
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); |
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#else |
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mr_energy = gain_corr_factor * ff_exp10((double)mr_energy / (20 << 23)) / |
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sqrt(adsp->scalarproduct_int16(fc_v, fc_v, subframe_size)); |
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return mr_energy >> 12; |
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#endif |
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} |
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float ff_amr_set_fixed_gain(float fixed_gain_factor, float fixed_mean_energy, |
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float *prediction_error, float energy_mean, |
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const float *pred_table) |
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{ |
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// Equations 66-69: |
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// ^g_c = ^gamma_gc * 100.05 (predicted dB + mean dB - dB of fixed vector) |
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// Note 10^(0.05 * -10log(average x2)) = 1/sqrt((average x2)). |
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float val = fixed_gain_factor * |
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ff_exp10(0.05 * |
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(avpriv_scalarproduct_float_c(pred_table, prediction_error, 4) + |
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energy_mean)) / |
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✓✗ |
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sqrtf(fixed_mean_energy ? fixed_mean_energy : 1.0); |
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// update quantified prediction error energy history |
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memmove(&prediction_error[0], &prediction_error[1], |
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3 * sizeof(prediction_error[0])); |
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prediction_error[3] = 20.0 * log10f(fixed_gain_factor); |
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return val; |
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} |
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void ff_decode_pitch_lag(int *lag_int, int *lag_frac, int pitch_index, |
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const int prev_lag_int, const int subframe, |
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int third_as_first, int resolution) |
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{ |
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/* Note n * 10923 >> 15 is floor(x/3) for 0 <= n <= 32767 */ |
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✓✓✓✓
✓✓ |
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if (subframe == 0 || (subframe == 2 && third_as_first)) { |
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✓✓ |
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if (pitch_index < 197) |
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pitch_index += 59; |
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else |
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pitch_index = 3 * pitch_index - 335; |
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} else { |
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✓✓ |
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if (resolution == 4) { |
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int search_range_min = av_clip(prev_lag_int - 5, PITCH_DELAY_MIN, |
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PITCH_DELAY_MAX - 9); |
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// decoding with 4-bit resolution |
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✓✓ |
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if (pitch_index < 4) { |
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// integer only precision for [search_range_min, search_range_min+3] |
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pitch_index = 3 * (pitch_index + search_range_min) + 1; |
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✓✓ |
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} else if (pitch_index < 12) { |
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// 1/3 fractional precision for [search_range_min+3 1/3, search_range_min+5 2/3] |
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pitch_index += 3 * search_range_min + 7; |
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} else { |
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// integer only precision for [search_range_min+6, search_range_min+9] |
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pitch_index = 3 * (pitch_index + search_range_min - 6) + 1; |
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} |
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} else { |
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// decoding with 5 or 6 bit resolution, 1/3 fractional precision |
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pitch_index--; |
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✓✓ |
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if (resolution == 5) { |
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pitch_index += 3 * av_clip(prev_lag_int - 10, PITCH_DELAY_MIN, |
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PITCH_DELAY_MAX - 19); |
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} else |
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pitch_index += 3 * av_clip(prev_lag_int - 5, PITCH_DELAY_MIN, |
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PITCH_DELAY_MAX - 9); |
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} |
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} |
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*lag_int = pitch_index * 10923 >> 15; |
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*lag_frac = pitch_index - 3 * *lag_int - 1; |
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} |