| /* |
| * G.729, G729 Annex D postfilter |
| * Copyright (c) 2008 Vladimir Voroshilov |
| * |
| * This file is part of FFmpeg. |
| * |
| * FFmpeg is free software; you can redistribute it and/or |
| * modify it under the terms of the GNU Lesser General Public |
| * License as published by the Free Software Foundation; either |
| * version 2.1 of the License, or (at your option) any later version. |
| * |
| * FFmpeg is distributed in the hope that it will be useful, |
| * but WITHOUT ANY WARRANTY; without even the implied warranty of |
| * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU |
| * Lesser General Public License for more details. |
| * |
| * You should have received a copy of the GNU Lesser General Public |
| * License along with FFmpeg; if not, write to the Free Software |
| * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA |
| */ |
| #ifndef AVCODEC_G729POSTFILTER_H |
| #define AVCODEC_G729POSTFILTER_H |
| |
| #include <stdint.h> |
| #include "audiodsp.h" |
| |
| /** |
| * tilt compensation factor (G.729, k1>0) |
| * 0.2 in Q15 |
| */ |
| #define G729_TILT_FACTOR_PLUS 6554 |
| |
| /** |
| * tilt compensation factor (G.729, k1<0) |
| * 0.9 in Q15 |
| */ |
| #define G729_TILT_FACTOR_MINUS 29491 |
| |
| /* 4.2.2 */ |
| #define FORMANT_PP_FACTOR_NUM 18022 //0.55 in Q15 |
| #define FORMANT_PP_FACTOR_DEN 22938 //0.70 in Q15 |
| |
| /** |
| * gain adjustment factor (G.729, 4.2.4) |
| * 0.9875 in Q15 |
| */ |
| #define G729_AGC_FACTOR 32358 |
| #define G729_AGC_FAC1 (32768-G729_AGC_FACTOR) |
| |
| /** |
| * 1.0 / (1.0 + 0.5) in Q15 |
| * where 0.5 is the minimum value of |
| * weight factor, controlling amount of long-term postfiltering |
| */ |
| #define MIN_LT_FILT_FACTOR_A 21845 |
| |
| /** |
| * Short interpolation filter length |
| */ |
| #define SHORT_INT_FILT_LEN 2 |
| |
| /** |
| * Long interpolation filter length |
| */ |
| #define LONG_INT_FILT_LEN 8 |
| |
| /** |
| * Number of analyzed fractional pitch delays in second stage of long-term |
| * postfilter |
| */ |
| #define ANALYZED_FRAC_DELAYS 7 |
| |
| /** |
| * Amount of past residual signal data stored in buffer |
| */ |
| #define RES_PREV_DATA_SIZE (PITCH_DELAY_MAX + LONG_INT_FILT_LEN + 1) |
| |
| /** |
| * \brief Signal postfiltering (4.2) |
| * \param dsp initialized DSP context |
| * \param ht_prev_data [in/out] (Q12) pointer to variable receiving tilt |
| * compensation filter data from previous subframe |
| * \param voicing [in/out] (Q0) pointer to variable receiving voicing decision |
| * \param lp_filter_coeffs (Q12) LP filter coefficients |
| * \param pitch_delay_int integer part of the pitch delay |
| * \param residual [in/out] (Q0) residual signal buffer (used in long-term postfilter) |
| * \param res_filter_data [in/out] (Q0) speech data of previous subframe |
| * \param pos_filter_data [in/out] (Q0) previous speech data for short-term postfilter |
| * \param speech [in/out] (Q0) signal buffer |
| * \param subframe_size size of subframe |
| * |
| * Filtering has the following stages: |
| * Long-term postfilter (4.2.1) |
| * Short-term postfilter (4.2.2). |
| * Tilt-compensation (4.2.3) |
| */ |
| void ff_g729_postfilter(AudioDSPContext *adsp, int16_t* ht_prev_data, int* voicing, |
| const int16_t *lp_filter_coeffs, int pitch_delay_int, |
| int16_t* residual, int16_t* res_filter_data, |
| int16_t* pos_filter_data, int16_t *speech, |
| int subframe_size); |
| |
| /** |
| * \brief Adaptive gain control (4.2.4) |
| * \param gain_before (Q0) gain of speech before applying postfilters |
| * \param gain_after (Q0) gain of speech after applying postfilters |
| * \param speech [in/out] (Q0) signal buffer |
| * \param subframe_size length of subframe |
| * \param gain_prev (Q12) previous value of gain coefficient |
| * |
| * \return (Q12) last value of gain coefficient |
| */ |
| int16_t ff_g729_adaptive_gain_control(int gain_before, int gain_after, int16_t *speech, |
| int subframe_size, int16_t gain_prev); |
| |
| #endif // AVCODEC_G729POSTFILTER_H |
