libavcodec/g729postfilter.h

   1 /*
   2  * G.729, G729 Annex D postfilter
   3  * Copyright (c) 2008 Vladimir Voroshilov
   4  *
   5  * This file is part of FFmpeg.
   6  *
   7  * FFmpeg is free software; you can redistribute it and/or
   8  * modify it under the terms of the GNU Lesser General Public
   9  * License as published by the Free Software Foundation; either
  10  * version 2.1 of the License, or (at your option) any later version.
  11  *
  12  * FFmpeg is distributed in the hope that it will be useful,
  13  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  14  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  15  * Lesser General Public License for more details.
  16  *
  17  * You should have received a copy of the GNU Lesser General Public
  18  * License along with FFmpeg; if not, write to the Free Software
  19  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
  20  */
  21 #ifndef AVCODEC_G729POSTFILTER_H
  22 #define AVCODEC_G729POSTFILTER_H
  23
  24 #include <stdint.h>
  25 #include "acelp_pitch_delay.h"
  26 #include "audiodsp.h"
  27
  28 /**
  29  * tilt compensation factor (G.729, k1>0)
  30  * 0.2 in Q15
  31  */
  32 #define G729_TILT_FACTOR_PLUS       6554
  33
  34 /**
  35  * tilt compensation factor (G.729, k1<0)
  36  * 0.9 in Q15
  37  */
  38 #define G729_TILT_FACTOR_MINUS     29491
  39
  40 /* 4.2.2 */
  41 #define FORMANT_PP_FACTOR_NUM  18022             //0.55 in Q15
  42 #define FORMANT_PP_FACTOR_DEN  22938             //0.70 in Q15
  43
  44 /**
  45  * gain adjustment factor (G.729, 4.2.4)
  46  * 0.9875 in Q15
  47  */
  48 #define G729_AGC_FACTOR            32358
  49 #define G729_AGC_FAC1 (32768-G729_AGC_FACTOR)
  50
  51 /**
  52  * 1.0 / (1.0 + 0.5) in Q15
  53  * where 0.5 is the minimum value of
  54  * weight factor, controlling amount of long-term postfiltering
  55  */
  56 #define MIN_LT_FILT_FACTOR_A       21845
  57
  58 /**
  59  * Short interpolation filter length
  60  */
  61 #define SHORT_INT_FILT_LEN         2
  62
  63 /**
  64  * Long interpolation filter length
  65  */
  66 #define LONG_INT_FILT_LEN          8
  67
  68 /**
  69  * Number of analyzed fractional pitch delays in second stage of long-term
  70  * postfilter
  71  */
  72 #define ANALYZED_FRAC_DELAYS       7
  73
  74 /**
  75  * Amount of past residual signal data stored in buffer
  76  */
  77 #define RES_PREV_DATA_SIZE (PITCH_DELAY_MAX + LONG_INT_FILT_LEN + 1)
  78
  79 /**
  80  * \brief Signal postfiltering (4.2)
  81  * \param dsp initialized DSP context
  82  * \param[in,out] ht_prev_data  (Q12) pointer to variable receiving tilt
  83  *                     compensation filter data from previous subframe
  84  * \param[in,out] voicing  (Q0) pointer to variable receiving voicing decision
  85  * \param lp_filter_coeffs (Q12) LP filter coefficients
  86  * \param pitch_delay_int integer part of the pitch delay
  87  * \param[in,out] residual  (Q0) residual signal buffer (used in long-term postfilter)
  88  * \param[in,out] res_filter_data  (Q0) speech data of previous subframe
  89  * \param[in,out] pos_filter_data  (Q0) previous speech data for short-term postfilter
  90  * \param[in,out] speech  (Q0) signal buffer
  91  * \param subframe_size size of subframe
  92  *
  93  * Filtering has the following  stages:
  94  *   Long-term postfilter (4.2.1)
  95  *   Short-term postfilter (4.2.2).
  96  *   Tilt-compensation (4.2.3)
  97  */
  98 void ff_g729_postfilter(AudioDSPContext *adsp, int16_t* ht_prev_data, int* voicing,
  99                      const int16_t *lp_filter_coeffs, int pitch_delay_int,
 100                      int16_t* residual, int16_t* res_filter_data,
 101                      int16_t* pos_filter_data, int16_t *speech,
 102                      int subframe_size);
 103
 104 /**
 105  * \brief Adaptive gain control (4.2.4)
 106  * \param gain_before (Q0) gain of speech before applying postfilters
 107  * \param gain_after  (Q0) gain of speech after applying postfilters
 108  * \param[in,out] speech  (Q0) signal buffer
 109  * \param subframe_size length of subframe
 110  * \param gain_prev (Q12) previous value of gain coefficient
 111  *
 112  * \return (Q12) last value of gain coefficient
 113  */
 114 int16_t ff_g729_adaptive_gain_control(int gain_before, int gain_after, int16_t *speech,
 115                                    int subframe_size, int16_t gain_prev);
 116
 117 #endif // AVCODEC_G729POSTFILTER_H