adx: calculate correct LPC coeffs
[libav.git] / libavcodec / adx.h
1 /*
2 * ADX ADPCM codecs
3 * Copyright (c) 2001,2003 BERO
4 *
5 * This file is part of Libav.
6 *
7 * Libav 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.
11 *
12 * Libav 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.
16 *
17 * You should have received a copy of the GNU Lesser General Public
18 * License along with Libav; if not, write to the Free Software
19 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
20 */
21
22 /**
23 * @file
24 * SEGA CRI adx codecs.
25 *
26 * Reference documents:
27 * http://ku-www.ss.titech.ac.jp/~yatsushi/adx.html
28 * adx2wav & wav2adx http://www.geocities.co.jp/Playtown/2004/
29 */
30
31 #ifndef AVCODEC_ADX_H
32 #define AVCODEC_ADX_H
33
34 typedef struct {
35 int s1,s2;
36 } ADXChannelState;
37
38 typedef struct {
39 int channels;
40 ADXChannelState prev[2];
41 int header_parsed;
42 unsigned char dec_temp[18*2];
43 int in_temp;
44 int cutoff;
45 int coeff[2];
46 } ADXContext;
47
48 #define COEFF_BITS 12
49
50 /**
51 * Calculate LPC coefficients based on cutoff frequency and sample rate.
52 *
53 * @param cutoff cutoff frequency
54 * @param sample_rate sample rate
55 * @param bits number of bits used to quantize coefficients
56 * @param[out] coeff 2 quantized LPC coefficients
57 */
58 void ff_adx_calculate_coeffs(int cutoff, int sample_rate, int bits, int *coeff);
59
60 #endif /* AVCODEC_ADX_H */