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ffmpeg / libavcodec / acelp_pitch_delay.c @ 2912e87a

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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 Libav.
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 *
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 * Libav 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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 * Libav 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 Libav; 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 "avcodec.h"
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#include "dsputil.h"
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#include "acelp_pitch_delay.h"
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#include "celp_math.h"
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int ff_acelp_decode_8bit_to_1st_delay3(int ac_index)
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{
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    ac_index += 58;
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    if(ac_index > 254)
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        ac_index = 3 * ac_index - 510;
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    return ac_index;
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}
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int ff_acelp_decode_4bit_to_2nd_delay3(
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        int ac_index,
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        int pitch_delay_min)
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{
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    if(ac_index < 4)
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        return 3 * (ac_index + pitch_delay_min);
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    else if(ac_index < 12)
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        return 3 * pitch_delay_min + ac_index + 6;
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    else
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        return 3 * (ac_index + pitch_delay_min) - 18;
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}
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int ff_acelp_decode_5_6_bit_to_2nd_delay3(
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        int ac_index,
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        int pitch_delay_min)
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{
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        return 3 * pitch_delay_min + ac_index - 2;
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}
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int ff_acelp_decode_9bit_to_1st_delay6(int ac_index)
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{
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    if(ac_index < 463)
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        return ac_index + 105;
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    else
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        return 6 * (ac_index - 368);
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}
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int ff_acelp_decode_6bit_to_2nd_delay6(
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        int ac_index,
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        int pitch_delay_min)
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{
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    return 6 * pitch_delay_min + ac_index - 3;
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}
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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(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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    DSPContext *dsp,
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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 * exp(M_LN10 / (20 << 23) * mr_energy) /
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                sqrt(dsp->scalarproduct_int16(fc_v, fc_v, subframe_size, 0));
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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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        exp2f(M_LOG2_10 * 0.05 *
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              (ff_dot_productf(pred_table, prediction_error, 4) +
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               energy_mean)) /
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        sqrtf(fixed_mean_energy);
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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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    if (subframe == 0 || (subframe == 2 && third_as_first)) {
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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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        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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            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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            } 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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            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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}