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