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/*
* AAC encoder TNS
* Copyright (C) 2015 Rostislav Pehlivanov
*
* 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
*/
/**
* @file
* AAC encoder temporal noise shaping
* @author Rostislav Pehlivanov ( atomnuker gmail com )
*/
#ifndef AVCODEC_AACENC_TNS_H
#define AVCODEC_AACENC_TNS_H
#include "aacenc.h"
/* Could be set to 3 to save an additional bit at the cost of little quality */
#define TNS_Q_BITS 4
/* Coefficient resolution in short windows */
#define TNS_Q_BITS_SHORT 3
/* TNS will only be used if the LPC gain is within these margins */
#define TNS_GAIN_THRESHOLD_LOW 1.437f
#define TNS_GAIN_THRESHOLD_HIGH 21.19f
/* If the energy ratio between the low SFBs vs the high SFBs is not between
* those two values, use 2 filters instead */
#define TNS_E_RATIO_LOW 0.77
#define TNS_E_RATIO_HIGH 1.23
/* Do not use TNS if the psy band spread is below this value */
#define TNS_SPREAD_THRESHOLD 0.5f
void ff_aac_encode_tns_info(AACEncContext *s, SingleChannelElement *sce);
void ff_aac_apply_tns(AACEncContext *s, SingleChannelElement *sce);
void ff_aac_search_for_tns(AACEncContext *s, SingleChannelElement *sce);
#endif /* AVCODEC_AACENC_TNS_H */
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