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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