3 * Copyright (C) 2015 Rostislav Pehlivanov
5 * This file is part of FFmpeg.
7 * FFmpeg is free software; you can redistribute it and/or
8 * modify it under the terms of the GNU Lesser General Public
9 * License as published by the Free Software Foundation; either
10 * version 2.1 of the License, or (at your option) any later version.
12 * FFmpeg is distributed in the hope that it will be useful,
13 * but WITHOUT ANY WARRANTY; without even the implied warranty of
14 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
15 * Lesser General Public License for more details.
17 * You should have received a copy of the GNU Lesser General Public
18 * License along with FFmpeg; if not, write to the Free Software
19 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
24 * AAC encoder temporal noise shaping
25 * @author Rostislav Pehlivanov ( atomnuker gmail com )
28 #ifndef AVCODEC_AACENC_TNS_H
29 #define AVCODEC_AACENC_TNS_H
33 /* Could be set to 3 to save an additional bit at the cost of little quality */
36 /* Coefficient resolution in short windows */
37 #define TNS_Q_BITS_SHORT 3
39 /* TNS will only be used if the LPC gain is within these margins */
40 #define TNS_GAIN_THRESHOLD_LOW 1.437f
41 #define TNS_GAIN_THRESHOLD_HIGH 21.19f
43 /* If the energy ratio between the low SFBs vs the high SFBs is not between
44 * those two values, use 2 filters instead */
45 #define TNS_E_RATIO_LOW 0.77
46 #define TNS_E_RATIO_HIGH 1.23
48 /* Do not use TNS if the psy band spread is below this value */
49 #define TNS_SPREAD_THRESHOLD 0.5f
51 void ff_aac_encode_tns_info(AACEncContext *s, SingleChannelElement *sce);
52 void ff_aac_apply_tns(AACEncContext *s, SingleChannelElement *sce);
53 void ff_aac_search_for_tns(AACEncContext *s, SingleChannelElement *sce);
55 #endif /* AVCODEC_AACENC_TNS_H */