/*
  * G.729, G729 Annex D postfilter
  * 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 FFMPEG_G729POSTFILTER_H
 #define FFMPEG_G729POSTFILTER_H
 
 #include <stdint.h>
 
 /**
  * tilt compensation factor (G.729, k1>0)
  * 0.2 in Q15
  */
 #define G729_TILT_FACTOR_PLUS       6554
 
 /**
  * tilt compensation factor (G.729, k1<0)
  * 0.9 in Q15
  */
 #define G729_TILT_FACTOR_MINUS     29491
 
 /* 4.2.2 */
 #define FORMANT_PP_FACTOR_NUM  18022             //0.55 in Q15
 #define FORMANT_PP_FACTOR_DEN  22938             //0.70 in Q15
 
 /**

  * gain adjustment factor (G.729, 4.2.4)
  * 0.9875 in Q15
  */
 #define G729_AGC_FACTOR            32358
 #define G729_AGC_FAC1 (32768-G729_AGC_FACTOR)
 
 /**

  * 1.0 / (1.0 + 0.5) in Q15
  * where 0.5 is the minimum value of
  * weight factor, controlling amount of long-term postfiltering
  */
 #define MIN_LT_FILT_FACTOR_A       21845
 
 /**
  * Short interpolation filter length
  */
 #define SHORT_INT_FILT_LEN         2
 
 /**
  * Long interpolation filter length
  */
 #define LONG_INT_FILT_LEN          8
 
 /**
  * Number of analyzed fractional pitch delays in second stage of long-term
  * postfilter
  */
 #define ANALYZED_FRAC_DELAYS       7
 
 /**
  * Amount of past residual signal data stored in buffer
  */
 #define RES_PREV_DATA_SIZE (PITCH_DELAY_MAX + LONG_INT_FILT_LEN + 1)
 
 /**
  * \brief Signal postfiltering (4.2)
  * \param dsp initialized DSP context
  * \param ht_prev_data [in/out] (Q12) pointer to variable receiving tilt
  *                     compensation filter data from previous subframe
  * \param voicing [in/out] (Q0) pointer to variable receiving voicing decision
  * \param lp_filter_coeffs (Q12) LP filter coefficients
  * \param pitch_delay_int integer part of the pitch delay
  * \param residual [in/out] (Q0) residual signal buffer (used in long-term postfilter)
  * \param res_filter_data [in/out] (Q0) speech data of previous subframe
  * \param pos_filter_data [in/out] (Q0) previous speech data for short-term postfilter
  * \param speech [in/out] (Q0) signal buffer
  * \param subframe_size size of subframe
  *
  * Filtering has the following  stages:
  *   Long-term postfilter (4.2.1)
  *   Short-term postfilter (4.2.2).
  *   Tilt-compensation (4.2.3)
  */

 void ff_g729_postfilter(DSPContext *dsp, int16_t* ht_prev_data, int* voicing,

                      const int16_t *lp_filter_coeffs, int pitch_delay_int,
                      int16_t* residual, int16_t* res_filter_data,
                      int16_t* pos_filter_data, int16_t *speech,
                      int subframe_size);
 

 /**
  * \brief Adaptive gain control (4.2.4)
  * \param gain_before (Q0) gain of speech before applying postfilters
  * \param gain_after  (Q0) gain of speech after applying postfilters
  * \param speech [in/out] (Q0) signal buffer
  * \param subframe_size length of subframe
  * \param gain_prev (Q12) previous value of gain coefficient
  *
  * \return (Q12) last value of gain coefficient
  */

 int16_t ff_g729_adaptive_gain_control(int gain_before, int gain_after, int16_t *speech,

                                    int subframe_size, int16_t gain_prev);
 

 #endif // FFMPEG_G729POSTFILTER_H