/*
  * gain code, gain pitch and pitch delay decoding
  *
  * Copyright (c) 2008 Vladimir Voroshilov
  *
  * This file is part of FFmpeg.
  *
  * FFmpeg 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.
  *
  * FFmpeg 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 FFmpeg; if not, write to the Free Software
  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
  */
 

 #ifndef AVCODEC_ACELP_PITCH_DELAY_H
 #define AVCODEC_ACELP_PITCH_DELAY_H

 
 #include <stdint.h>

 #include "dsputil.h"

 
 #define PITCH_DELAY_MIN             20
 #define PITCH_DELAY_MAX             143
 
 /**

  * @brief Decode pitch delay of the first subframe encoded by 8 bits with 1/3

  *        resolution.

  * @param ac_index adaptive codebook index (8 bits)

  *

  * @return pitch delay in 1/3 units

  *
  * Pitch delay is coded:
  *    with 1/3 resolution, 19  < pitch_delay <  85
  *    integers only,       85 <= pitch_delay <= 143
  */
 int ff_acelp_decode_8bit_to_1st_delay3(int ac_index);
 
 /**

  * @brief Decode pitch delay of the second subframe encoded by 5 or 6 bits

  *        with 1/3 precision.

  * @param ac_index adaptive codebook index (5 or 6 bits)
  * @param pitch_delay_min lower bound (integer) of pitch delay interval

  *                      for second subframe
  *

  * @return pitch delay in 1/3 units

  *
  * Pitch delay is coded:
  *    with 1/3 resolution, -6 < pitch_delay - int(prev_pitch_delay) < 5
  *

  * @remark The routine is used in G.729 @@8k, AMR @@10.2k, AMR @@7.95k,

  *         AMR @@7.4k for the second subframe.

  */
 int ff_acelp_decode_5_6_bit_to_2nd_delay3(
         int ac_index,
         int pitch_delay_min);
 
 /**

  * @brief Decode pitch delay with 1/3 precision.
  * @param ac_index adaptive codebook index (4 bits)
  * @param pitch_delay_min lower bound (integer) of pitch delay interval for

  *                      second subframe
  *

  * @return pitch delay in 1/3 units

  *
  * Pitch delay is coded:
  *    integers only,          -6  < pitch_delay - int(prev_pitch_delay) <= -2
  *    with 1/3 resolution,    -2  < pitch_delay - int(prev_pitch_delay) <  1
  *    integers only,           1 <= pitch_delay - int(prev_pitch_delay) <  5
  *

  * @remark The routine is used in G.729 @@6.4k, AMR @@6.7k, AMR @@5.9k,

  *         AMR @@5.15k, AMR @@4.75k for the second subframe.

  */
 int ff_acelp_decode_4bit_to_2nd_delay3(
         int ac_index,
         int pitch_delay_min);
 
 /**

  * @brief Decode pitch delay of the first subframe encoded by 9 bits

  *        with 1/6 precision.

  * @param ac_index adaptive codebook index (9 bits)

  *

  * @return pitch delay in 1/6 units

  *
  * Pitch delay is coded:
  *    with 1/6 resolution,  17  < pitch_delay <  95
  *    integers only,        95 <= pitch_delay <= 143
  *

  * @remark The routine is used in AMR @@12.2k for the first and third subframes.

  */
 int ff_acelp_decode_9bit_to_1st_delay6(int ac_index);
 
 /**

  * @brief Decode pitch delay of the second subframe encoded by 6 bits

  *        with 1/6 precision.

  * @param ac_index adaptive codebook index (6 bits)
  * @param pitch_delay_min lower bound (integer) of pitch delay interval for

  *                      second subframe
  *

  * @return pitch delay in 1/6 units

  *
  * Pitch delay is coded:
  *    with 1/6 resolution, -6 < pitch_delay - int(prev_pitch_delay) < 5
  *

  * @remark The routine is used in AMR @@12.2k for the second and fourth subframes.

  */
 int ff_acelp_decode_6bit_to_2nd_delay6(
         int ac_index,
         int pitch_delay_min);
 
 /**

  * @brief Update past quantized energies
  * @param[in,out]  quant_energy  past quantized energies (5.10)
  * @param gain_corr_factor gain correction factor
  * @param log2_ma_pred_order log2() of MA prediction order
  * @param erasure frame erasure flag

  *
  * If frame erasure flag is not equal to zero, memory is updated with
  * averaged energy, attenuated by 4dB:
  *     max(avg(quant_energy[i])-4, -14), i=0,ma_pred_order
  *
  * In normal mode memory is updated with
  *     Er - Ep = 20 * log10(gain_corr_factor)
  *

  * @remark The routine is used in G.729 and AMR (all modes).

  */
 void ff_acelp_update_past_gain(
         int16_t* quant_energy,
         int gain_corr_factor,
         int log2_ma_pred_order,
         int erasure);
 
 /**

  * @brief Decode the adaptive codebook gain and add

  *        correction (4.1.5 and 3.9.1 of G.729).

  * @param dsp initialized dsputil context
  * @param gain_corr_factor gain correction factor (2.13)
  * @param fc_v fixed-codebook vector (2.13)
  * @param mr_energy mean innovation energy and fixed-point correction (7.13)
  * @param[in,out]  quant_energy  past quantized energies (5.10)
  * @param subframe_size length of subframe

  *

  * @return quantized fixed-codebook gain (14.1)

  *
  * The routine implements equations 69, 66 and 71 of the G.729 specification (3.9.1)
  *
  *    Em   - mean innovation energy (dB, constant, depends on decoding algorithm)
  *    Ep   - mean-removed predicted energy (dB)
  *    Er   - mean-removed innovation energy (dB)
  *    Ei   - mean energy of the fixed-codebook contribution (dB)
  *    N    - subframe_size
  *    M    - MA (Moving Average) prediction order
  *    gc   - fixed-codebook gain
  *    gc_p - predicted fixed-codebook gain
  *
  *    Fixed codebook gain is computed using predicted gain gc_p and
  *    correction factor gain_corr_factor as shown below:
  *
  *        gc = gc_p * gain_corr_factor
  *
  *    The predicted fixed codebook gain gc_p is found by predicting
  *    the energy of the fixed-codebook contribution from the energy
  *    of previous fixed-codebook contributions.
  *
  *        mean = 1/N * sum(i,0,N){ fc_v[i] * fc_v[i] }
  *
  *        Ei = 10log(mean)
  *
  *        Er = 10log(1/N * gc^2 * mean) - Em = 20log(gc) + Ei - Em
  *
  *    Replacing Er with Ep and gc with gc_p we will receive:
  *
  *        Ep = 10log(1/N * gc_p^2 * mean) - Em = 20log(gc_p) + Ei - Em
  *
  *    and from above:
  *
  *        gc_p = 10^((Ep - Ei + Em) / 20)
  *
  *    Ep is predicted using past energies and prediction coefficients:
  *
  *        Ep = sum(i,0,M){ ma_prediction_coeff[i] * quant_energy[i] }
  *
  *    gc_p in fixed-point arithmetic is calculated as following:
  *
  *        mean = 1/N * sum(i,0,N){ (fc_v[i] / 2^13) * (fc_v[i] / 2^13) } =
  *        = 1/N * sum(i,0,N) { fc_v[i] * fc_v[i] } / 2^26
  *
  *        Ei = 10log(mean) = -10log(N) - 10log(2^26) +
  *        + 10log(sum(i,0,N) { fc_v[i] * fc_v[i] })
  *
  *        Ep - Ei + Em = Ep + Em + 10log(N) + 10log(2^26) -
  *        - 10log(sum(i,0,N) { fc_v[i] * fc_v[i] }) =
  *        = Ep + mr_energy - 10log(sum(i,0,N) { fc_v[i] * fc_v[i] })
  *
  *        gc_p = 10 ^ ((Ep - Ei + Em) / 20) =
  *        = 2 ^ (3.3219 * (Ep - Ei + Em) / 20) = 2 ^ (0.166 * (Ep - Ei + Em))
  *
  *    where
  *
  *        mr_energy = Em + 10log(N) + 10log(2^26)
  *

  * @remark The routine is used in G.729 and AMR (all modes).

  */
 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 max_pred_order);
 

 /**
  * Calculate fixed gain (part of section 6.1.3 of AMR spec)
  *
  * @param fixed_gain_factor gain correction factor

  * @param fixed_mean_energy mean decoded algebraic codebook vector energy

  * @param prediction_error vector of the quantified predictor errors of
  *        the four previous subframes. It is updated by this function.
  * @param energy_mean desired mean innovation energy
  * @param pred_table table of four moving average coefficients
  */
 float ff_amr_set_fixed_gain(float fixed_gain_factor, float fixed_mean_energy,
                             float *prediction_error, float energy_mean,
                             const float *pred_table);
 

 
 /**
  * Decode the adaptive codebook index to the integer and fractional parts
  * of the pitch lag for one subframe at 1/3 fractional precision.
  *
  * The choice of pitch lag is described in 3GPP TS 26.090 section 5.6.1.
  *
  * @param lag_int             integer part of pitch lag of the current subframe
  * @param lag_frac            fractional part of pitch lag of the current subframe
  * @param pitch_index         parsed adaptive codebook (pitch) index
  * @param prev_lag_int        integer part of pitch lag for the previous subframe
  * @param subframe            current subframe number
  * @param third_as_first      treat the third frame the same way as the first
  */
 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);
 

 #endif /* AVCODEC_ACELP_PITCH_DELAY_H */