FFmpeg
mlp.h
Go to the documentation of this file.
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 4
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 */
74 typedef struct FilterParams {
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 
80  int coeff_bits;
81  int coeff_shift;
82 } FilterParams;
83 
84 /** sample data coding information */
85 typedef struct ChannelParams {
86  FilterParams filter_params[NUM_FILTERS];
87  int32_t coeff[NUM_FILTERS][MAX_FIR_ORDER];
88 
89  int16_t huff_offset; ///< Offset to apply to residual values.
90  int32_t sign_huff_offset; ///< sign/rounding-corrected version of huff_offset
91  uint8_t codebook; ///< Which VLC codebook to use to read residuals.
92  uint8_t huff_lsbs; ///< Size of residual suffix not encoded using VLC.
93 } ChannelParams;
94 
95 /** Tables defining the Huffman codes.
96  * There are three entropy coding methods used in MLP (four if you count
97  * "none" as a method). These use the same sequences for codes starting with
98  * 00 or 01, but have different codes starting with 1.
99  */
100 extern const uint8_t ff_mlp_huffman_tables[3][18][2];
101 
102 typedef struct {
103  uint8_t channel_occupancy;
104  uint8_t group1_channels;
105  uint8_t group2_channels;
106  uint8_t summary_info;
107 } ChannelInformation;
108 
109 /** Tables defining channel information.
110  *
111  * Possible channel arrangements are:
112  *
113  * (Group 1) C
114  * (Group 1) L, R
115  * (Group 1) Lf, Rf / (Group 2) S
116  * (Group 1) Lf, Rf / (Group 2) Ls, Rs
117  * (Group 1) Lf, Rf / (Group 2) LFE
118  * (Group 1) Lf, Rf / (Group 2) LFE, S
119  * (Group 1) Lf, Rf / (Group 2) LFE, Ls, Rs
120  * (Group 1) Lf, Rf / (Group 2) C
121  * (Group 1) Lf, Rf / (Group 2) C, S
122  * (Group 1) Lf, Rf / (Group 2) C, Ls, Rs
123  * (Group 1) Lf, Rf / (Group 2) C, LFE
124  * (Group 1) Lf, Rf / (Group 2) C, LFE, S
125  * (Group 1) Lf, Rf / (Group 2) C, LFE, Ls, Rs
126  * (Group 1) Lf, Rf C / (Group 2) S
127  * (Group 1) Lf, Rf C / (Group 2) Ls, Rs
128  * (Group 1) Lf, Rf C / (Group 2) LFE
129  * (Group 1) Lf, Rf C / (Group 2) LFE, S
130  * (Group 1) Lf, Rf C / (Group 2) LFE, Ls, Rs
131  * (Group 1) Lf, Rf Ls Rs / (Group 2) LFE
132  * (Group 1) Lf, Rf Ls Rs / (Group 2) C
133  * (Group 1) Lf, Rf, Ls, Rs / (Group 2) C, LFE
134  */
135 extern const ChannelInformation ff_mlp_ch_info[21];
136 
137 extern const uint64_t ff_mlp_channel_layouts[12];
138 
139 /** MLP uses checksums that seem to be based on the standard CRC algorithm, but
140  * are not (in implementation terms, the table lookup and XOR are reversed).
141  * We can implement this behavior using a standard av_crc on all but the
142  * last element, then XOR that with the last element.
143  */
144 uint8_t ff_mlp_checksum8 (const uint8_t *buf, unsigned int buf_size);
145 uint16_t ff_mlp_checksum16(const uint8_t *buf, unsigned int buf_size);
146 
147 /** Calculate an 8-bit checksum over a restart header -- a non-multiple-of-8
148  * number of bits, starting two bits into the first byte of buf.
149  */
150 uint8_t ff_mlp_restart_checksum(const uint8_t *buf, unsigned int bit_size);
151 
152 /** XOR together all the bytes of a buffer.
153  * Does this belong in dspcontext?
154  */
155 uint8_t ff_mlp_calculate_parity(const uint8_t *buf, unsigned int buf_size);
156 
157 void ff_mlp_init_crc(void);
158 
159 /** XOR four bytes into one. */
160 static inline uint8_t xor_32_to_8(uint32_t value)
161 {
162  value ^= value >> 16;
163  value ^= value >> 8;
164  return value;
165 }
166 
167 typedef enum THDChannelModifier {
168  THD_CH_MODIFIER_NOTINDICATED = 0x0,
169  THD_CH_MODIFIER_STEREO = 0x0, // Stereo (not Dolby Surround)
170  THD_CH_MODIFIER_LTRT = 0x1, // Dolby Surround
171  THD_CH_MODIFIER_LBINRBIN = 0x2, // Dolby Headphone
172  THD_CH_MODIFIER_MONO = 0x3, // Mono or Dual Mono
173  THD_CH_MODIFIER_NOTSURROUNDEX = 0x1, // Not Dolby Digital EX
174  THD_CH_MODIFIER_SURROUNDEX = 0x2, // Dolby Digital EX
175 } THDChannelModifier;
176 
177 #endif /* AVCODEC_MLP_H */
ChannelInformation::summary_info
uint8_t summary_info
Definition: mlp.h:106
THD_CH_MODIFIER_NOTINDICATED
@ THD_CH_MODIFIER_NOTINDICATED
Definition: mlp.h:168
ff_mlp_huffman_tables
const uint8_t ff_mlp_huffman_tables[3][18][2]
Tables defining the Huffman codes.
Definition: mlp.c:28
ChannelParams::codebook
uint8_t codebook
Which VLC codebook to use to read residuals.
Definition: mlp.h:91
xor_32_to_8
static uint8_t xor_32_to_8(uint32_t value)
XOR four bytes into one.
Definition: mlp.h:160
THD_CH_MODIFIER_SURROUNDEX
@ THD_CH_MODIFIER_SURROUNDEX
Definition: mlp.h:174
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:94
ChannelInformation::group2_channels
uint8_t group2_channels
Definition: mlp.h:105
ff_mlp_ch_info
const ChannelInformation ff_mlp_ch_info[21]
Tables defining channel information.
Definition: mlp.c:44
ChannelParams::filter_params
FilterParams filter_params[NUM_FILTERS]
Definition: mlp.h:86
ChannelParams::huff_lsbs
uint8_t huff_lsbs
Size of residual suffix not encoded using VLC.
Definition: mlp.h:92
ChannelInformation
Definition: mlp.h:102
ff_mlp_checksum16
uint16_t ff_mlp_checksum16(const uint8_t *buf, unsigned int buf_size)
Definition: mlp.c:85
buf
void * buf
Definition: avisynth_c.h:766
ChannelInformation::group1_channels
uint8_t group1_channels
Definition: mlp.h:104
THD_CH_MODIFIER_LTRT
@ THD_CH_MODIFIER_LTRT
Definition: mlp.h:170
ff_mlp_init_crc
void ff_mlp_init_crc(void)
Definition: mlp.c:75
int32_t
int32_t
Definition: audio_convert.c:194
ChannelParams::coeff
int32_t coeff[NUM_FILTERS][MAX_FIR_ORDER]
Definition: mlp.h:87
THDChannelModifier
THDChannelModifier
Definition: mlp.h:167
THD_CH_MODIFIER_LBINRBIN
@ THD_CH_MODIFIER_LBINRBIN
Definition: mlp.h:171
FilterParams::coeff_shift
int coeff_shift
Definition: mlp.h:81
FilterParams
filter data
Definition: mlp.h:74
FilterParams::coeff_bits
int coeff_bits
Definition: mlp.h:80
NUM_FILTERS
#define NUM_FILTERS
number of allowed filters
Definition: mlp.h:61
FilterParams::order
uint8_t order
number of taps in filter
Definition: mlp.h:75
ChannelParams::huff_offset
int16_t huff_offset
Offset to apply to residual values.
Definition: mlp.h:89
MAX_FIR_ORDER
#define MAX_FIR_ORDER
The maximum number of taps in IIR and FIR filters.
Definition: mlp.h:64
ff_mlp_channel_layouts
const uint64_t ff_mlp_channel_layouts[12]
Definition: mlp.c:58
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
uint8_t
uint8_t
Definition: audio_convert.c:194
ChannelParams
sample data coding information
Definition: mlp.h:85
ChannelParams::sign_huff_offset
int32_t sign_huff_offset
sign/rounding-corrected version of huff_offset
Definition: mlp.h:90
avcodec.h
ChannelInformation::channel_occupancy
uint8_t channel_occupancy
Definition: mlp.h:103
FilterParams::state
int32_t state[MAX_FIR_ORDER]
Definition: mlp.h:78
THD_CH_MODIFIER_STEREO
@ THD_CH_MODIFIER_STEREO
Definition: mlp.h:169
THD_CH_MODIFIER_NOTSURROUNDEX
@ THD_CH_MODIFIER_NOTSURROUNDEX
Definition: mlp.h:173
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:120
FilterParams::shift
uint8_t shift
Right shift to apply to output of filter.
Definition: mlp.h:76
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:101
THD_CH_MODIFIER_MONO
@ THD_CH_MODIFIER_MONO
Definition: mlp.h:172
Generated on Wed Aug 24 2022 21:26:50 for FFmpeg by   doxygen 1.8.17