2 * G.729, G729 Annex D postfilter
3 * Copyright (c) 2008 Vladimir Voroshilov
5 * This file is part of FFmpeg.
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
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15 * Lesser General Public License for more details.
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
21 #ifndef AVCODEC_G729POSTFILTER_H
22 #define AVCODEC_G729POSTFILTER_H
28 * tilt compensation factor (G.729, k1>0)
31 #define G729_TILT_FACTOR_PLUS 6554
34 * tilt compensation factor (G.729, k1<0)
37 #define G729_TILT_FACTOR_MINUS 29491
40 #define FORMANT_PP_FACTOR_NUM 18022 //0.55 in Q15
41 #define FORMANT_PP_FACTOR_DEN 22938 //0.70 in Q15
44 * gain adjustment factor (G.729, 4.2.4)
47 #define G729_AGC_FACTOR 32358
48 #define G729_AGC_FAC1 (32768-G729_AGC_FACTOR)
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
55 #define MIN_LT_FILT_FACTOR_A 21845
58 * Short interpolation filter length
60 #define SHORT_INT_FILT_LEN 2
63 * Long interpolation filter length
65 #define LONG_INT_FILT_LEN 8
68 * Number of analyzed fractional pitch delays in second stage of long-term
71 #define ANALYZED_FRAC_DELAYS 7
74 * Amount of past residual signal data stored in buffer
76 #define RES_PREV_DATA_SIZE (PITCH_DELAY_MAX + LONG_INT_FILT_LEN + 1)
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
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)
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,
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
111 * \return (Q12) last value of gain coefficient
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);
116 #endif // AVCODEC_G729POSTFILTER_H