PeerStreamer

/*

 * 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 "avcodec.h"

#include "dsputil.h"

#include "acelp_pitch_delay.h"

#include "celp_math.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];

#ifdef G729_BITEXACT

    mr_energy += (((-6165LL * ff_log2(dsp->scalarproduct_int16(fc_v, fc_v, subframe_size, 0))) >> 3) & ~0x3ff);

    mr_energy = (5439 * (mr_energy >> 15)) >> 8;           // (0.15) = (0.15) * (7.23)

    return bidir_sal(

               ((ff_exp2(mr_energy & 0x7fff) + 16) >> 5) * (gain_corr_factor >> 1),

               (mr_energy >> 15) - 25

           );

#else

    mr_energy = gain_corr_factor * exp(M_LN10 / (20 << 23) * mr_energy) /

                sqrt(dsp->scalarproduct_int16(fc_v, fc_v, subframe_size, 0));

    return mr_energy >> 12;

#endif

}

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_dot_productf(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;

}