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g729postfilter.h
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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 FFMPEG_G729POSTFILTER_H
22 #define FFMPEG_G729POSTFILTER_H
23 
24 #include <stdint.h>
25 #include "dsputil.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(DSPContext *dsp, 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 // FFMPEG_G729POSTFILTER_H