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 "audiodsp.h" 26 27 /** 28 * tilt compensation factor (G.729, k1>0) 29 * 0.2 in Q15 30 */ 31 #define G729_TILT_FACTOR_PLUS 6554 32 33 /** 34 * tilt compensation factor (G.729, k1<0) 35 * 0.9 in Q15 36 */ 37 #define G729_TILT_FACTOR_MINUS 29491 38 39 /* 4.2.2 */ 40 #define FORMANT_PP_FACTOR_NUM 18022 //0.55 in Q15 41 #define FORMANT_PP_FACTOR_DEN 22938 //0.70 in Q15 42 43 /** 44 * gain adjustment factor (G.729, 4.2.4) 45 * 0.9875 in Q15 46 */ 47 #define G729_AGC_FACTOR 32358 48 #define G729_AGC_FAC1 (32768-G729_AGC_FACTOR) 49 50 /** 51 * 1.0 / (1.0 + 0.5) in Q15 52 * where 0.5 is the minimum value of 53 * weight factor, controlling amount of long-term postfiltering 54 */ 55 #define MIN_LT_FILT_FACTOR_A 21845 56 57 /** 58 * Short interpolation filter length 59 */ 60 #define SHORT_INT_FILT_LEN 2 61 62 /** 63 * Long interpolation filter length 64 */ 65 #define LONG_INT_FILT_LEN 8 66 67 /** 68 * Number of analyzed fractional pitch delays in second stage of long-term 69 * postfilter 70 */ 71 #define ANALYZED_FRAC_DELAYS 7 72 73 /** 74 * Amount of past residual signal data stored in buffer 75 */ 76 #define RES_PREV_DATA_SIZE (PITCH_DELAY_MAX + LONG_INT_FILT_LEN + 1) 77 78 /** 79 * \brief Signal postfiltering (4.2) 80 * \param dsp initialized DSP context 81 * \param ht_prev_data [in/out] (Q12) pointer to variable receiving tilt 82 * compensation filter data from previous subframe 83 * \param voicing [in/out] (Q0) pointer to variable receiving voicing decision 84 * \param lp_filter_coeffs (Q12) LP filter coefficients 85 * \param pitch_delay_int integer part of the pitch delay 86 * \param residual [in/out] (Q0) residual signal buffer (used in long-term postfilter) 87 * \param res_filter_data [in/out] (Q0) speech data of previous subframe 88 * \param pos_filter_data [in/out] (Q0) previous speech data for short-term postfilter 89 * \param speech [in/out] (Q0) signal buffer 90 * \param subframe_size size of subframe 91 * 92 * Filtering has the following stages: 93 * Long-term postfilter (4.2.1) 94 * Short-term postfilter (4.2.2). 95 * Tilt-compensation (4.2.3) 96 */ 97 void ff_g729_postfilter(AudioDSPContext *adsp, int16_t* ht_prev_data, int* voicing, 98 const int16_t *lp_filter_coeffs, int pitch_delay_int, 99 int16_t* residual, int16_t* res_filter_data, 100 int16_t* pos_filter_data, int16_t *speech, 101 int subframe_size); 102 103 /** 104 * \brief Adaptive gain control (4.2.4) 105 * \param gain_before (Q0) gain of speech before applying postfilters 106 * \param gain_after (Q0) gain of speech after applying postfilters 107 * \param speech [in/out] (Q0) signal buffer 108 * \param subframe_size length of subframe 109 * \param gain_prev (Q12) previous value of gain coefficient 110 * 111 * \return (Q12) last value of gain coefficient 112 */ 113 int16_t ff_g729_adaptive_gain_control(int gain_before, int gain_after, int16_t *speech, 114 int subframe_size, int16_t gain_prev); 115 116 #endif // AVCODEC_G729POSTFILTER_H 117