Libav
cabac.c
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1 /*
2  * H.26L/H.264/AVC/JVT/14496-10/... encoder/decoder
3  * Copyright (c) 2003 Michael Niedermayer <michaelni@gmx.at>
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 
27 #include <string.h>
28 
29 #include "libavutil/common.h"
30 
31 #include "cabac.h"
32 #include "cabac_functions.h"
33 
34 const uint8_t ff_h264_cabac_tables[512 + 4*2*64 + 4*64 + 63] = {
35  9,8,7,7,6,6,6,6,5,5,5,5,5,5,5,5,
36  4,4,4,4,4,4,4,4,4,4,4,4,4,4,4,4,
37  3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,
38  3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,
39  2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,
40  2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,
41  2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,
42  2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,
43  1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,
44  1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,
45  1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,
46  1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,
47  0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,
48  0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,
49  0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,
50  0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,
51  0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,
52  0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,
53  0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,
54  0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,
55  // LPS range
56  -128, -128, -128, -128, -128, -128, 123, 123,
57  116, 116, 111, 111, 105, 105, 100, 100,
58  95, 95, 90, 90, 85, 85, 81, 81,
59  77, 77, 73, 73, 69, 69, 66, 66,
60  62, 62, 59, 59, 56, 56, 53, 53,
61  51, 51, 48, 48, 46, 46, 43, 43,
62  41, 41, 39, 39, 37, 37, 35, 35,
63  33, 33, 32, 32, 30, 30, 29, 29,
64  27, 27, 26, 26, 24, 24, 23, 23,
65  22, 22, 21, 21, 20, 20, 19, 19,
66  18, 18, 17, 17, 16, 16, 15, 15,
67  14, 14, 14, 14, 13, 13, 12, 12,
68  12, 12, 11, 11, 11, 11, 10, 10,
69  10, 10, 9, 9, 9, 9, 8, 8,
70  8, 8, 7, 7, 7, 7, 7, 7,
71  6, 6, 6, 6, 6, 6, 2, 2,
72  -80, -80, -89, -89, -98, -98, -106, -106,
73  -114, -114, -121, -121, -128, -128, 122, 122,
74  116, 116, 110, 110, 104, 104, 99, 99,
75  94, 94, 89, 89, 85, 85, 80, 80,
76  76, 76, 72, 72, 69, 69, 65, 65,
77  62, 62, 59, 59, 56, 56, 53, 53,
78  50, 50, 48, 48, 45, 45, 43, 43,
79  41, 41, 39, 39, 37, 37, 35, 35,
80  33, 33, 31, 31, 30, 30, 28, 28,
81  27, 27, 26, 26, 24, 24, 23, 23,
82  22, 22, 21, 21, 20, 20, 19, 19,
83  18, 18, 17, 17, 16, 16, 15, 15,
84  14, 14, 14, 14, 13, 13, 12, 12,
85  12, 12, 11, 11, 11, 11, 10, 10,
86  9, 9, 9, 9, 9, 9, 8, 8,
87  8, 8, 7, 7, 7, 7, 2, 2,
88  -48, -48, -59, -59, -69, -69, -78, -78,
89  -87, -87, -96, -96, -104, -104, -112, -112,
90  -119, -119, -126, -126, 123, 123, 117, 117,
91  111, 111, 105, 105, 100, 100, 95, 95,
92  90, 90, 86, 86, 81, 81, 77, 77,
93  73, 73, 69, 69, 66, 66, 63, 63,
94  59, 59, 56, 56, 54, 54, 51, 51,
95  48, 48, 46, 46, 43, 43, 41, 41,
96  39, 39, 37, 37, 35, 35, 33, 33,
97  32, 32, 30, 30, 29, 29, 27, 27,
98  26, 26, 25, 25, 23, 23, 22, 22,
99  21, 21, 20, 20, 19, 19, 18, 18,
100  17, 17, 16, 16, 15, 15, 15, 15,
101  14, 14, 13, 13, 12, 12, 12, 12,
102  11, 11, 11, 11, 10, 10, 10, 10,
103  9, 9, 9, 9, 8, 8, 2, 2,
104  -16, -16, -29, -29, -40, -40, -51, -51,
105  -61, -61, -71, -71, -81, -81, -90, -90,
106  -98, -98, -106, -106, -114, -114, -121, -121,
107  -128, -128, 122, 122, 116, 116, 110, 110,
108  104, 104, 99, 99, 94, 94, 89, 89,
109  85, 85, 80, 80, 76, 76, 72, 72,
110  69, 69, 65, 65, 62, 62, 59, 59,
111  56, 56, 53, 53, 50, 50, 48, 48,
112  45, 45, 43, 43, 41, 41, 39, 39,
113  37, 37, 35, 35, 33, 33, 31, 31,
114  30, 30, 28, 28, 27, 27, 25, 25,
115  24, 24, 23, 23, 22, 22, 21, 21,
116  20, 20, 19, 19, 18, 18, 17, 17,
117  16, 16, 15, 15, 14, 14, 14, 14,
118  13, 13, 12, 12, 12, 12, 11, 11,
119  11, 11, 10, 10, 9, 9, 2, 2,
120  // mlps state
121  127, 126, 77, 76, 77, 76, 75, 74,
122  75, 74, 75, 74, 73, 72, 73, 72,
123  73, 72, 71, 70, 71, 70, 71, 70,
124  69, 68, 69, 68, 67, 66, 67, 66,
125  67, 66, 65, 64, 65, 64, 63, 62,
126  61, 60, 61, 60, 61, 60, 59, 58,
127  59, 58, 57, 56, 55, 54, 55, 54,
128  53, 52, 53, 52, 51, 50, 49, 48,
129  49, 48, 47, 46, 45, 44, 45, 44,
130  43, 42, 43, 42, 39, 38, 39, 38,
131  37, 36, 37, 36, 33, 32, 33, 32,
132  31, 30, 31, 30, 27, 26, 27, 26,
133  25, 24, 23, 22, 23, 22, 19, 18,
134  19, 18, 17, 16, 15, 14, 13, 12,
135  11, 10, 9, 8, 9, 8, 5, 4,
136  5, 4, 3, 2, 1, 0, 0, 1,
137  2, 3, 4, 5, 6, 7, 8, 9,
138  10, 11, 12, 13, 14, 15, 16, 17,
139  18, 19, 20, 21, 22, 23, 24, 25,
140  26, 27, 28, 29, 30, 31, 32, 33,
141  34, 35, 36, 37, 38, 39, 40, 41,
142  42, 43, 44, 45, 46, 47, 48, 49,
143  50, 51, 52, 53, 54, 55, 56, 57,
144  58, 59, 60, 61, 62, 63, 64, 65,
145  66, 67, 68, 69, 70, 71, 72, 73,
146  74, 75, 76, 77, 78, 79, 80, 81,
147  82, 83, 84, 85, 86, 87, 88, 89,
148  90, 91, 92, 93, 94, 95, 96, 97,
149  98, 99, 100, 101, 102, 103, 104, 105,
150  106, 107, 108, 109, 110, 111, 112, 113,
151  114, 115, 116, 117, 118, 119, 120, 121,
152  122, 123, 124, 125, 124, 125, 126, 127,
153  // last_coeff_flag_offset_8x8
154  0, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1,
155  2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2,
156  3, 3, 3, 3, 3, 3, 3, 3, 4, 4, 4, 4, 4, 4, 4, 4,
157  5, 5, 5, 5, 6, 6, 6, 6, 7, 7, 7, 7, 8, 8, 8
158 };
159 
163 void ff_init_cabac_decoder(CABACContext *c, const uint8_t *buf, int buf_size){
164  c->bytestream_start=
165  c->bytestream= buf;
166  c->bytestream_end= buf + buf_size;
167 
168 #if CABAC_BITS == 16
169  c->low = (*c->bytestream++)<<18;
170  c->low+= (*c->bytestream++)<<10;
171 #else
172  c->low = (*c->bytestream++)<<10;
173 #endif
174  c->low+= ((*c->bytestream++)<<2) + 2;
175  c->range= 0x1FE;
176 }
const uint8_t * bytestream_end
Definition: cabac.h:48
const uint8_t * bytestream
Definition: cabac.h:47
uint8_t
const uint8_t * bytestream_start
Definition: cabac.h:46
Context Adaptive Binary Arithmetic Coder inline functions.
int range
Definition: cabac.h:45
const uint8_t ff_h264_cabac_tables[512+4 *2 *64+4 *64+63]
Definition: cabac.c:34
int low
Definition: cabac.h:44
common internal and external API header
void ff_init_cabac_decoder(CABACContext *c, const uint8_t *buf, int buf_size)
Definition: cabac.c:163
Context Adaptive Binary Arithmetic Coder.