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Diffstat (limited to 'libavcodec/g729postfilter.h')
-rw-r--r-- | libavcodec/g729postfilter.h | 116 |
1 files changed, 116 insertions, 0 deletions
diff --git a/libavcodec/g729postfilter.h b/libavcodec/g729postfilter.h new file mode 100644 index 0000000..5c2aaf2 --- /dev/null +++ b/libavcodec/g729postfilter.h @@ -0,0 +1,116 @@ +/* + * 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 |