/* * 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 FFMPEG_G729POSTFILTER_H #define FFMPEG_G729POSTFILTER_H #include <stdint.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(DSPContext *dsp, 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 // FFMPEG_G729POSTFILTER_H