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 #include "get_bits.h"
31 #include "cabac.h"
32 #include "cabac_functions.h"
33 
34 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 };
56 
57 static const uint8_t lps_range[64][4]= {
58 {128,176,208,240}, {128,167,197,227}, {128,158,187,216}, {123,150,178,205},
59 {116,142,169,195}, {111,135,160,185}, {105,128,152,175}, {100,122,144,166},
60 { 95,116,137,158}, { 90,110,130,150}, { 85,104,123,142}, { 81, 99,117,135},
61 { 77, 94,111,128}, { 73, 89,105,122}, { 69, 85,100,116}, { 66, 80, 95,110},
62 { 62, 76, 90,104}, { 59, 72, 86, 99}, { 56, 69, 81, 94}, { 53, 65, 77, 89},
63 { 51, 62, 73, 85}, { 48, 59, 69, 80}, { 46, 56, 66, 76}, { 43, 53, 63, 72},
64 { 41, 50, 59, 69}, { 39, 48, 56, 65}, { 37, 45, 54, 62}, { 35, 43, 51, 59},
65 { 33, 41, 48, 56}, { 32, 39, 46, 53}, { 30, 37, 43, 50}, { 29, 35, 41, 48},
66 { 27, 33, 39, 45}, { 26, 31, 37, 43}, { 24, 30, 35, 41}, { 23, 28, 33, 39},
67 { 22, 27, 32, 37}, { 21, 26, 30, 35}, { 20, 24, 29, 33}, { 19, 23, 27, 31},
68 { 18, 22, 26, 30}, { 17, 21, 25, 28}, { 16, 20, 23, 27}, { 15, 19, 22, 25},
69 { 14, 18, 21, 24}, { 14, 17, 20, 23}, { 13, 16, 19, 22}, { 12, 15, 18, 21},
70 { 12, 14, 17, 20}, { 11, 14, 16, 19}, { 11, 13, 15, 18}, { 10, 12, 15, 17},
71 { 10, 12, 14, 16}, { 9, 11, 13, 15}, { 9, 11, 12, 14}, { 8, 10, 12, 14},
72 { 8, 9, 11, 13}, { 7, 9, 11, 12}, { 7, 9, 10, 12}, { 7, 8, 10, 11},
73 { 6, 8, 9, 11}, { 6, 7, 9, 10}, { 6, 7, 8, 9}, { 2, 2, 2, 2},
74 };
75 
76 static uint8_t h264_mps_state[2 * 64];
77 
78 static const uint8_t mps_state[64]= {
79  1, 2, 3, 4, 5, 6, 7, 8,
80  9,10,11,12,13,14,15,16,
81  17,18,19,20,21,22,23,24,
82  25,26,27,28,29,30,31,32,
83  33,34,35,36,37,38,39,40,
84  41,42,43,44,45,46,47,48,
85  49,50,51,52,53,54,55,56,
86  57,58,59,60,61,62,62,63,
87 };
88 
89 static const uint8_t lps_state[64]= {
90  0, 0, 1, 2, 2, 4, 4, 5,
91  6, 7, 8, 9, 9,11,11,12,
92  13,13,15,15,16,16,18,18,
93  19,19,21,21,22,22,23,24,
94  24,25,26,26,27,27,28,29,
95  29,30,30,30,31,32,32,33,
96  33,33,34,34,35,35,35,36,
97  36,36,37,37,37,38,38,63,
98 };
99 
101  0, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1,
102  2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2,
103  3, 3, 3, 3, 3, 3, 3, 3, 4, 4, 4, 4, 4, 4, 4, 4,
104  5, 5, 5, 5, 6, 6, 6, 6, 7, 7, 7, 7, 8, 8, 8
105 };
106 
111 void ff_init_cabac_encoder(CABACContext *c, uint8_t *buf, int buf_size){
112  init_put_bits(&c->pb, buf, buf_size);
113 
114  c->low= 0;
115  c->range= 0x1FE;
116  c->outstanding_count= 0;
117  c->pb.bit_left++; //avoids firstBitFlag
118 }
119 
124 void ff_init_cabac_decoder(CABACContext *c, const uint8_t *buf, int buf_size){
125  c->bytestream_start=
126  c->bytestream= buf;
127  c->bytestream_end= buf + buf_size;
128 
129 #if CABAC_BITS == 16
130  c->low = (*c->bytestream++)<<18;
131  c->low+= (*c->bytestream++)<<10;
132 #else
133  c->low = (*c->bytestream++)<<10;
134 #endif
135  c->low+= ((*c->bytestream++)<<2) + 2;
136  c->range= 0x1FE;
137 }
138 
140  int i, j;
141 
142  for(i=0; i<64; i++){
143  for(j=0; j<4; j++){ //FIXME check if this is worth the 1 shift we save
144  ff_h264_lps_range[j*2*64+2*i+0]=
145  ff_h264_lps_range[j*2*64+2*i+1]= lps_range[i][j];
146  }
147 
148  ff_h264_mlps_state[128+2*i+0]=
149  h264_mps_state[2 * i + 0] = 2 * mps_state[i] + 0;
150  ff_h264_mlps_state[128+2*i+1]=
151  h264_mps_state[2 * i + 1] = 2 * mps_state[i] + 1;
152 
153  if( i ){
154  ff_h264_mlps_state[128-2*i-1]= 2*lps_state[i]+0;
155  ff_h264_mlps_state[128-2*i-2]= 2*lps_state[i]+1;
156  }else{
157  ff_h264_mlps_state[128-2*i-1]= 1;
158  ff_h264_mlps_state[128-2*i-2]= 0;
159  }
160  }
161  for(i=0; i< 63; i++){
163  }
164 }