yading@10: /*
yading@10:  * G.729, G729 Annex D postfilter
yading@10:  * Copyright (c) 2008 Vladimir Voroshilov
yading@10:  *
yading@10:  * This file is part of FFmpeg.
yading@10:  *
yading@10:  * FFmpeg is free software; you can redistribute it and/or
yading@10:  * modify it under the terms of the GNU Lesser General Public
yading@10:  * License as published by the Free Software Foundation; either
yading@10:  * version 2.1 of the License, or (at your option) any later version.
yading@10:  *
yading@10:  * FFmpeg is distributed in the hope that it will be useful,
yading@10:  * but WITHOUT ANY WARRANTY; without even the implied warranty of
yading@10:  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
yading@10:  * Lesser General Public License for more details.
yading@10:  *
yading@10:  * You should have received a copy of the GNU Lesser General Public
yading@10:  * License along with FFmpeg; if not, write to the Free Software
yading@10:  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
yading@10:  */
yading@10: #ifndef FFMPEG_G729POSTFILTER_H
yading@10: #define FFMPEG_G729POSTFILTER_H
yading@10: 
yading@10: #include <stdint.h>
yading@10: #include "dsputil.h"
yading@10: 
yading@10: /**
yading@10:  * tilt compensation factor (G.729, k1>0)
yading@10:  * 0.2 in Q15
yading@10:  */
yading@10: #define G729_TILT_FACTOR_PLUS       6554
yading@10: 
yading@10: /**
yading@10:  * tilt compensation factor (G.729, k1<0)
yading@10:  * 0.9 in Q15
yading@10:  */
yading@10: #define G729_TILT_FACTOR_MINUS     29491
yading@10: 
yading@10: /* 4.2.2 */
yading@10: #define FORMANT_PP_FACTOR_NUM  18022             //0.55 in Q15
yading@10: #define FORMANT_PP_FACTOR_DEN  22938             //0.70 in Q15
yading@10: 
yading@10: /**
yading@10:  * gain adjustment factor (G.729, 4.2.4)
yading@10:  * 0.9875 in Q15
yading@10:  */
yading@10: #define G729_AGC_FACTOR            32358
yading@10: #define G729_AGC_FAC1 (32768-G729_AGC_FACTOR)
yading@10: 
yading@10: /**
yading@10:  * 1.0 / (1.0 + 0.5) in Q15
yading@10:  * where 0.5 is the minimum value of
yading@10:  * weight factor, controlling amount of long-term postfiltering
yading@10:  */
yading@10: #define MIN_LT_FILT_FACTOR_A       21845
yading@10: 
yading@10: /**
yading@10:  * Short interpolation filter length
yading@10:  */
yading@10: #define SHORT_INT_FILT_LEN         2
yading@10: 
yading@10: /**
yading@10:  * Long interpolation filter length
yading@10:  */
yading@10: #define LONG_INT_FILT_LEN          8
yading@10: 
yading@10: /**
yading@10:  * Number of analyzed fractional pitch delays in second stage of long-term
yading@10:  * postfilter
yading@10:  */
yading@10: #define ANALYZED_FRAC_DELAYS       7
yading@10: 
yading@10: /**
yading@10:  * Amount of past residual signal data stored in buffer
yading@10:  */
yading@10: #define RES_PREV_DATA_SIZE (PITCH_DELAY_MAX + LONG_INT_FILT_LEN + 1)
yading@10: 
yading@10: /**
yading@10:  * \brief Signal postfiltering (4.2)
yading@10:  * \param dsp initialized DSP context
yading@10:  * \param ht_prev_data [in/out] (Q12) pointer to variable receiving tilt
yading@10:  *                     compensation filter data from previous subframe
yading@10:  * \param voicing [in/out] (Q0) pointer to variable receiving voicing decision
yading@10:  * \param lp_filter_coeffs (Q12) LP filter coefficients
yading@10:  * \param pitch_delay_int integer part of the pitch delay
yading@10:  * \param residual [in/out] (Q0) residual signal buffer (used in long-term postfilter)
yading@10:  * \param res_filter_data [in/out] (Q0) speech data of previous subframe
yading@10:  * \param pos_filter_data [in/out] (Q0) previous speech data for short-term postfilter
yading@10:  * \param speech [in/out] (Q0) signal buffer
yading@10:  * \param subframe_size size of subframe
yading@10:  *
yading@10:  * Filtering has the following  stages:
yading@10:  *   Long-term postfilter (4.2.1)
yading@10:  *   Short-term postfilter (4.2.2).
yading@10:  *   Tilt-compensation (4.2.3)
yading@10:  */
yading@10: void ff_g729_postfilter(DSPContext *dsp, int16_t* ht_prev_data, int* voicing,
yading@10:                      const int16_t *lp_filter_coeffs, int pitch_delay_int,
yading@10:                      int16_t* residual, int16_t* res_filter_data,
yading@10:                      int16_t* pos_filter_data, int16_t *speech,
yading@10:                      int subframe_size);
yading@10: 
yading@10: /**
yading@10:  * \brief Adaptive gain control (4.2.4)
yading@10:  * \param gain_before (Q0) gain of speech before applying postfilters
yading@10:  * \param gain_after  (Q0) gain of speech after applying postfilters
yading@10:  * \param speech [in/out] (Q0) signal buffer
yading@10:  * \param subframe_size length of subframe
yading@10:  * \param gain_prev (Q12) previous value of gain coefficient
yading@10:  *
yading@10:  * \return (Q12) last value of gain coefficient
yading@10:  */
yading@10: int16_t ff_g729_adaptive_gain_control(int gain_before, int gain_after, int16_t *speech,
yading@10:                                    int subframe_size, int16_t gain_prev);
yading@10: 
yading@10: #endif // FFMPEG_G729POSTFILTER_H