FFmpeg
mlp.h
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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 "libavutil/channel_layout.h"
28 
29 #define SYNC_MLP 0xbb
30 #define SYNC_TRUEHD 0xba
31 
32 /** Last possible matrix channel for each codec */
33 #define MAX_MATRIX_CHANNEL_MLP 5
34 #define MAX_MATRIX_CHANNEL_TRUEHD 7
35 /** Maximum number of channels in a valid stream.
36  * MLP : 5.1 + 2 noise channels -> 8 channels
37  * TrueHD: 7.1 -> 8 channels
38  */
39 #define MAX_CHANNELS 8
40 
41 /** Maximum number of matrices used in decoding; most streams have one matrix
42  * per output channel, but some rematrix a channel (usually 0) more than once.
43  */
44 #define MAX_MATRICES_MLP 6
45 #define MAX_MATRICES_TRUEHD 8
46 #define MAX_MATRICES 8
47 
48 /** Maximum number of substreams that can be decoded.
49  * MLP's limit is 2. TrueHD supports at least up to 3.
50  */
51 #define MAX_SUBSTREAMS 4
52 
53 /** which multiple of 48000 the maximum sample rate is */
54 #define MAX_RATEFACTOR 4
55 /** maximum sample frequency seen in files */
56 #define MAX_SAMPLERATE (MAX_RATEFACTOR * 48000)
57 
58 /** maximum number of audio samples within one access unit */
59 #define MAX_BLOCKSIZE (40 * MAX_RATEFACTOR)
60 /** next power of two greater than MAX_BLOCKSIZE */
61 #define MAX_BLOCKSIZE_POW2 (64 * MAX_RATEFACTOR)
62 
63 /** number of allowed filters */
64 #define NUM_FILTERS 2
65 
66 /** The maximum number of taps in IIR and FIR filters. */
67 #define MAX_FIR_ORDER 8
68 #define MAX_IIR_ORDER 4
69 
70 /** Code that signals end of a stream. */
71 #define END_OF_STREAM 0xd234d234
72 
73 #define PARAM_BLOCKSIZE (1 << 7)
74 #define PARAM_MATRIX (1 << 6)
75 #define PARAM_OUTSHIFT (1 << 5)
76 #define PARAM_QUANTSTEP (1 << 4)
77 #define PARAM_FIR (1 << 3)
78 #define PARAM_IIR (1 << 2)
79 #define PARAM_HUFFOFFSET (1 << 1)
80 #define PARAM_PRESENCE (1 << 0)
81 
82 #define FIR 0
83 #define IIR 1
84 
85 /** filter data */
86 typedef struct FilterParams {
87  uint8_t order; ///< number of taps in filter
88  uint8_t shift; ///< Right shift to apply to output of filter.
89 
90  int32_t state[MAX_FIR_ORDER];
91 
92  int coeff_bits;
93  int coeff_shift;
94 } FilterParams;
95 
96 /** sample data coding information */
97 typedef struct ChannelParams {
98  FilterParams filter_params[NUM_FILTERS];
99  int32_t coeff[NUM_FILTERS][MAX_FIR_ORDER];
100 
101  int16_t huff_offset; ///< Offset to apply to residual values.
102  int32_t sign_huff_offset; ///< sign/rounding-corrected version of huff_offset
103  uint8_t codebook; ///< Which VLC codebook to use to read residuals.
104  uint8_t huff_lsbs; ///< Size of residual suffix not encoded using VLC.
105 } ChannelParams;
106 
107 /** Tables defining the Huffman codes.
108  * There are three entropy coding methods used in MLP (four if you count
109  * "none" as a method). These use the same sequences for codes starting with
110  * 00 or 01, but have different codes starting with 1.
111  */
112 extern const uint8_t ff_mlp_huffman_tables[3][18][2];
113 
114 typedef struct {
115  uint8_t channel_occupancy;
116  uint8_t group1_channels;
117  uint8_t group2_channels;
118  uint8_t summary_info;
119 } ChannelInformation;
120 
121 /** Tables defining channel information.
122  *
123  * Possible channel arrangements are:
124  *
125  * (Group 1) C
126  * (Group 1) L, R
127  * (Group 1) Lf, Rf / (Group 2) S
128  * (Group 1) Lf, Rf / (Group 2) Ls, Rs
129  * (Group 1) Lf, Rf / (Group 2) LFE
130  * (Group 1) Lf, Rf / (Group 2) LFE, S
131  * (Group 1) Lf, Rf / (Group 2) LFE, Ls, Rs
132  * (Group 1) Lf, Rf / (Group 2) C
133  * (Group 1) Lf, Rf / (Group 2) C, S
134  * (Group 1) Lf, Rf / (Group 2) C, Ls, Rs
135  * (Group 1) Lf, Rf / (Group 2) C, LFE
136  * (Group 1) Lf, Rf / (Group 2) C, LFE, S
137  * (Group 1) Lf, Rf / (Group 2) C, LFE, Ls, Rs
138  * (Group 1) Lf, Rf C / (Group 2) S
139  * (Group 1) Lf, Rf C / (Group 2) Ls, Rs
140  * (Group 1) Lf, Rf C / (Group 2) LFE
141  * (Group 1) Lf, Rf C / (Group 2) LFE, S
142  * (Group 1) Lf, Rf C / (Group 2) LFE, Ls, Rs
143  * (Group 1) Lf, Rf Ls Rs / (Group 2) LFE
144  * (Group 1) Lf, Rf Ls Rs / (Group 2) C
145  * (Group 1) Lf, Rf, Ls, Rs / (Group 2) C, LFE
146  */
147 extern const ChannelInformation ff_mlp_ch_info[21];
148 
149 extern const AVChannelLayout ff_mlp_ch_layouts[12];
150 
151 /** MLP uses checksums that seem to be based on the standard CRC algorithm, but
152  * are not (in implementation terms, the table lookup and XOR are reversed).
153  * We can implement this behavior using a standard av_crc on all but the
154  * last element, then XOR that with the last element.
155  */
156 uint8_t ff_mlp_checksum8 (const uint8_t *buf, unsigned int buf_size);
157 uint16_t ff_mlp_checksum16(const uint8_t *buf, unsigned int buf_size);
158 
159 /** Calculate an 8-bit checksum over a restart header -- a non-multiple-of-8
160  * number of bits, starting two bits into the first byte of buf.
161  */
162 uint8_t ff_mlp_restart_checksum(const uint8_t *buf, unsigned int bit_size);
163 
164 /** XOR together all the bytes of a buffer.
165  * Does this belong in dspcontext?
166  */
167 uint8_t ff_mlp_calculate_parity(const uint8_t *buf, unsigned int buf_size);
168 
169 void ff_mlp_init_crc(void);
170 
171 /** XOR four bytes into one. */
172 static inline uint8_t xor_32_to_8(uint32_t value)
173 {
174  value ^= value >> 16;
175  value ^= value >> 8;
176  return value;
177 }
178 
179 typedef enum THDChannelModifier {
180  THD_CH_MODIFIER_NOTINDICATED = 0x0,
181  THD_CH_MODIFIER_STEREO = 0x0, // Stereo (not Dolby Surround)
182  THD_CH_MODIFIER_LTRT = 0x1, // Dolby Surround
183  THD_CH_MODIFIER_LBINRBIN = 0x2, // Dolby Headphone
184  THD_CH_MODIFIER_MONO = 0x3, // Mono or Dual Mono
185  THD_CH_MODIFIER_NOTSURROUNDEX = 0x1, // Not Dolby Digital EX
186  THD_CH_MODIFIER_SURROUNDEX = 0x2, // Dolby Digital EX
187 } THDChannelModifier;
188 
189 #endif /* AVCODEC_MLP_H */
ChannelInformation::summary_info
uint8_t summary_info
Definition: mlp.h:118
THD_CH_MODIFIER_NOTINDICATED
@ THD_CH_MODIFIER_NOTINDICATED
Definition: mlp.h:180
ff_mlp_huffman_tables
const uint8_t ff_mlp_huffman_tables[3][18][2]
Tables defining the Huffman codes.
Definition: mlp.c:30
ChannelParams::codebook
uint8_t codebook
Which VLC codebook to use to read residuals.
Definition: mlp.h:103
xor_32_to_8
static uint8_t xor_32_to_8(uint32_t value)
XOR four bytes into one.
Definition: mlp.h:172
THD_CH_MODIFIER_SURROUNDEX
@ THD_CH_MODIFIER_SURROUNDEX
Definition: mlp.h:186
ff_mlp_checksum8
uint8_t ff_mlp_checksum8(const uint8_t *buf, unsigned int buf_size)
MLP uses checksums that seem to be based on the standard CRC algorithm, but are not (in implementatio...
Definition: mlp.c:98
ChannelInformation::group2_channels
uint8_t group2_channels
Definition: mlp.h:117
ff_mlp_ch_info
const ChannelInformation ff_mlp_ch_info[21]
Tables defining channel information.
Definition: mlp.c:46
ChannelParams::filter_params
FilterParams filter_params[NUM_FILTERS]
Definition: mlp.h:98
ChannelParams::huff_lsbs
uint8_t huff_lsbs
Size of residual suffix not encoded using VLC.
Definition: mlp.h:104
ChannelInformation
Definition: mlp.h:114
ff_mlp_checksum16
uint16_t ff_mlp_checksum16(const uint8_t *buf, unsigned int buf_size)
Definition: mlp.c:89
ff_mlp_ch_layouts
const AVChannelLayout ff_mlp_ch_layouts[12]
Definition: mlp.c:60
ChannelInformation::group1_channels
uint8_t group1_channels
Definition: mlp.h:116
THD_CH_MODIFIER_LTRT
@ THD_CH_MODIFIER_LTRT
Definition: mlp.h:182
ff_mlp_init_crc
void ff_mlp_init_crc(void)
Definition: mlp.c:83
ChannelParams::coeff
int32_t coeff[NUM_FILTERS][MAX_FIR_ORDER]
Definition: mlp.h:99
THDChannelModifier
THDChannelModifier
Definition: mlp.h:179
THD_CH_MODIFIER_LBINRBIN
@ THD_CH_MODIFIER_LBINRBIN
Definition: mlp.h:183
FilterParams::coeff_shift
int coeff_shift
Definition: mlp.h:93
FilterParams
filter data
Definition: mlp.h:86
AVChannelLayout
An AVChannelLayout holds information about the channel layout of audio data.
Definition: channel_layout.h:318
FilterParams::coeff_bits
int coeff_bits
Definition: mlp.h:92
NUM_FILTERS
#define NUM_FILTERS
number of allowed filters
Definition: mlp.h:64
FilterParams::order
uint8_t order
number of taps in filter
Definition: mlp.h:87
ChannelParams::huff_offset
int16_t huff_offset
Offset to apply to residual values.
Definition: mlp.h:101
MAX_FIR_ORDER
#define MAX_FIR_ORDER
The maximum number of taps in IIR and FIR filters.
Definition: mlp.h:67
value
it s the only field you need to keep assuming you have a context There is some magic you don t need to care about around this just let it vf default value
Definition: writing_filters.txt:86
ChannelParams
sample data coding information
Definition: mlp.h:97
ChannelParams::sign_huff_offset
int32_t sign_huff_offset
sign/rounding-corrected version of huff_offset
Definition: mlp.h:102
ChannelInformation::channel_occupancy
uint8_t channel_occupancy
Definition: mlp.h:115
FilterParams::state
int32_t state[MAX_FIR_ORDER]
Definition: mlp.h:90
THD_CH_MODIFIER_STEREO
@ THD_CH_MODIFIER_STEREO
Definition: mlp.h:181
channel_layout.h
THD_CH_MODIFIER_NOTSURROUNDEX
@ THD_CH_MODIFIER_NOTSURROUNDEX
Definition: mlp.h:185
ff_mlp_calculate_parity
uint8_t ff_mlp_calculate_parity(const uint8_t *buf, unsigned int buf_size)
XOR together all the bytes of a buffer.
Definition: mlp.c:124
int32_t
int32_t
Definition: audioconvert.c:56
FilterParams::shift
uint8_t shift
Right shift to apply to output of filter.
Definition: mlp.h:88
ff_mlp_restart_checksum
uint8_t ff_mlp_restart_checksum(const uint8_t *buf, unsigned int bit_size)
Calculate an 8-bit checksum over a restart header – a non-multiple-of-8 number of bits,...
Definition: mlp.c:105
THD_CH_MODIFIER_MONO
@ THD_CH_MODIFIER_MONO
Definition: mlp.h:184
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