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 ht_prev_data [in/out] (Q12) pointer to variable receiving tilt 83 * compensation filter data from previous subframe 84 * \param voicing [in/out] (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 residual [in/out] (Q0) residual signal buffer (used in long-term postfilter) 88 * \param res_filter_data [in/out] (Q0) speech data of previous subframe 89 * \param pos_filter_data [in/out] (Q0) previous speech data for short-term postfilter 90 * \param speech [in/out] (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 speech [in/out] (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 118