1/*
2 * MLP codec common header file
3 * Copyright (c) 2007-2008 Ian Caulfield
4 *
5 * This file is part of FFmpeg.
6 *
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.
11 *
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.
16 *
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
20 */
21
22#ifndef AVCODEC_MLP_H
23#define AVCODEC_MLP_H
24
25#include <stdint.h>
26
27#include "avcodec.h"
28
29/** Last possible matrix channel for each codec */
30#define MAX_MATRIX_CHANNEL_MLP      5
31#define MAX_MATRIX_CHANNEL_TRUEHD   7
32/** Maximum number of channels in a valid stream.
33 *  MLP   : 5.1 + 2 noise channels -> 8 channels
34 *  TrueHD: 7.1                    -> 8 channels
35 */
36#define MAX_CHANNELS                8
37
38/** Maximum number of matrices used in decoding; most streams have one matrix
39 *  per output channel, but some rematrix a channel (usually 0) more than once.
40 */
41#define MAX_MATRICES_MLP            6
42#define MAX_MATRICES_TRUEHD         8
43#define MAX_MATRICES                8
44
45/** Maximum number of substreams that can be decoded.
46 *  MLP's limit is 2. TrueHD supports at least up to 3.
47 */
48#define MAX_SUBSTREAMS      3
49
50/** which multiple of 48000 the maximum sample rate is */
51#define MAX_RATEFACTOR      4
52/** maximum sample frequency seen in files */
53#define MAX_SAMPLERATE      (MAX_RATEFACTOR * 48000)
54
55/** maximum number of audio samples within one access unit */
56#define MAX_BLOCKSIZE       (40 * MAX_RATEFACTOR)
57/** next power of two greater than MAX_BLOCKSIZE */
58#define MAX_BLOCKSIZE_POW2  (64 * MAX_RATEFACTOR)
59
60/** number of allowed filters */
61#define NUM_FILTERS         2
62
63/** The maximum number of taps in IIR and FIR filters. */
64#define MAX_FIR_ORDER       8
65#define MAX_IIR_ORDER       4
66
67/** Code that signals end of a stream. */
68#define END_OF_STREAM       0xd234d234
69
70#define FIR 0
71#define IIR 1
72
73/** filter data */
74typedef struct {
75    uint8_t     order; ///< number of taps in filter
76    uint8_t     shift; ///< Right shift to apply to output of filter.
77
78    int32_t     state[MAX_FIR_ORDER];
79} FilterParams;
80
81/** sample data coding information */
82typedef struct {
83    FilterParams filter_params[NUM_FILTERS];
84    int32_t     coeff[NUM_FILTERS][MAX_FIR_ORDER];
85
86    int16_t     huff_offset;      ///< Offset to apply to residual values.
87    int32_t     sign_huff_offset; ///< sign/rounding-corrected version of huff_offset
88    uint8_t     codebook;         ///< Which VLC codebook to use to read residuals.
89    uint8_t     huff_lsbs;        ///< Size of residual suffix not encoded using VLC.
90} ChannelParams;
91
92/** Tables defining the Huffman codes.
93 *  There are three entropy coding methods used in MLP (four if you count
94 *  "none" as a method). These use the same sequences for codes starting with
95 *  00 or 01, but have different codes starting with 1.
96 */
97extern const uint8_t ff_mlp_huffman_tables[3][18][2];
98
99/** MLP uses checksums that seem to be based on the standard CRC algorithm, but
100 *  are not (in implementation terms, the table lookup and XOR are reversed).
101 *  We can implement this behavior using a standard av_crc on all but the
102 *  last element, then XOR that with the last element.
103 */
104uint8_t  ff_mlp_checksum8 (const uint8_t *buf, unsigned int buf_size);
105uint16_t ff_mlp_checksum16(const uint8_t *buf, unsigned int buf_size);
106
107/** Calculate an 8-bit checksum over a restart header -- a non-multiple-of-8
108 *  number of bits, starting two bits into the first byte of buf.
109 */
110uint8_t ff_mlp_restart_checksum(const uint8_t *buf, unsigned int bit_size);
111
112/** XOR together all the bytes of a buffer.
113 *  Does this belong in dspcontext?
114 */
115uint8_t ff_mlp_calculate_parity(const uint8_t *buf, unsigned int buf_size);
116
117void ff_mlp_init_crc(void);
118
119/** XOR four bytes into one. */
120static inline uint8_t xor_32_to_8(uint32_t value)
121{
122    value ^= value >> 16;
123    value ^= value >>  8;
124    return value;
125}
126
127#endif /* AVCODEC_MLP_H */
128