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 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/**
23 * @file libavcodec/cabac.c
24 * Context Adaptive Binary Arithmetic Coder.
25 */
26
27#include <string.h>
28
29#include "libavutil/common.h"
30#include "bitstream.h"
31#include "cabac.h"
32
33static const uint8_t lps_range[64][4]= {
34{128,176,208,240}, {128,167,197,227}, {128,158,187,216}, {123,150,178,205},
35{116,142,169,195}, {111,135,160,185}, {105,128,152,175}, {100,122,144,166},
36{ 95,116,137,158}, { 90,110,130,150}, { 85,104,123,142}, { 81, 99,117,135},
37{ 77, 94,111,128}, { 73, 89,105,122}, { 69, 85,100,116}, { 66, 80, 95,110},
38{ 62, 76, 90,104}, { 59, 72, 86, 99}, { 56, 69, 81, 94}, { 53, 65, 77, 89},
39{ 51, 62, 73, 85}, { 48, 59, 69, 80}, { 46, 56, 66, 76}, { 43, 53, 63, 72},
40{ 41, 50, 59, 69}, { 39, 48, 56, 65}, { 37, 45, 54, 62}, { 35, 43, 51, 59},
41{ 33, 41, 48, 56}, { 32, 39, 46, 53}, { 30, 37, 43, 50}, { 29, 35, 41, 48},
42{ 27, 33, 39, 45}, { 26, 31, 37, 43}, { 24, 30, 35, 41}, { 23, 28, 33, 39},
43{ 22, 27, 32, 37}, { 21, 26, 30, 35}, { 20, 24, 29, 33}, { 19, 23, 27, 31},
44{ 18, 22, 26, 30}, { 17, 21, 25, 28}, { 16, 20, 23, 27}, { 15, 19, 22, 25},
45{ 14, 18, 21, 24}, { 14, 17, 20, 23}, { 13, 16, 19, 22}, { 12, 15, 18, 21},
46{ 12, 14, 17, 20}, { 11, 14, 16, 19}, { 11, 13, 15, 18}, { 10, 12, 15, 17},
47{ 10, 12, 14, 16}, {  9, 11, 13, 15}, {  9, 11, 12, 14}, {  8, 10, 12, 14},
48{  8,  9, 11, 13}, {  7,  9, 11, 12}, {  7,  9, 10, 12}, {  7,  8, 10, 11},
49{  6,  8,  9, 11}, {  6,  7,  9, 10}, {  6,  7,  8,  9}, {  2,  2,  2,  2},
50};
51
52uint8_t ff_h264_mlps_state[4*64];
53uint8_t ff_h264_lps_range[4*2*64];
54uint8_t ff_h264_lps_state[2*64];
55uint8_t ff_h264_mps_state[2*64];
56
57static const uint8_t mps_state[64]= {
58  1, 2, 3, 4, 5, 6, 7, 8,
59  9,10,11,12,13,14,15,16,
60 17,18,19,20,21,22,23,24,
61 25,26,27,28,29,30,31,32,
62 33,34,35,36,37,38,39,40,
63 41,42,43,44,45,46,47,48,
64 49,50,51,52,53,54,55,56,
65 57,58,59,60,61,62,62,63,
66};
67
68static const uint8_t lps_state[64]= {
69  0, 0, 1, 2, 2, 4, 4, 5,
70  6, 7, 8, 9, 9,11,11,12,
71 13,13,15,15,16,16,18,18,
72 19,19,21,21,22,22,23,24,
73 24,25,26,26,27,27,28,29,
74 29,30,30,30,31,32,32,33,
75 33,33,34,34,35,35,35,36,
76 36,36,37,37,37,38,38,63,
77};
78#if 0
79const uint8_t ff_h264_norm_shift_old[128]= {
80 7,6,5,5,4,4,4,4,3,3,3,3,3,3,3,3,
81 2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,
82 1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,
83 1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,
84 0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,
85 0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,
86 0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,
87 0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,
88};
89#endif
90const uint8_t ff_h264_norm_shift[512]= {
91 9,8,7,7,6,6,6,6,5,5,5,5,5,5,5,5,
92 4,4,4,4,4,4,4,4,4,4,4,4,4,4,4,4,
93 3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,
94 3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,
95 2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,
96 2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,
97 2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,
98 2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,
99 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,
100 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,
101 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,
102 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,
103 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,
104 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,
105 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,
106 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,
107 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,
108 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,
109 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,
110 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,
111};
112
113/**
114 *
115 * @param buf_size size of buf in bits
116 */
117void ff_init_cabac_encoder(CABACContext *c, uint8_t *buf, int buf_size){
118    init_put_bits(&c->pb, buf, buf_size);
119
120    c->low= 0;
121    c->range= 0x1FE;
122    c->outstanding_count= 0;
123#ifdef STRICT_LIMITS
124    c->sym_count =0;
125#endif
126
127    c->pb.bit_left++; //avoids firstBitFlag
128}
129
130/**
131 *
132 * @param buf_size size of buf in bits
133 */
134void ff_init_cabac_decoder(CABACContext *c, const uint8_t *buf, int buf_size){
135    c->bytestream_start=
136    c->bytestream= buf;
137    c->bytestream_end= buf + buf_size;
138
139#if CABAC_BITS == 16
140    c->low =  (*c->bytestream++)<<18;
141    c->low+=  (*c->bytestream++)<<10;
142#else
143    c->low =  (*c->bytestream++)<<10;
144#endif
145    c->low+= ((*c->bytestream++)<<2) + 2;
146    c->range= 0x1FE;
147}
148
149void ff_init_cabac_states(CABACContext *c){
150    int i, j;
151
152    for(i=0; i<64; i++){
153        for(j=0; j<4; j++){ //FIXME check if this is worth the 1 shift we save
154            ff_h264_lps_range[j*2*64+2*i+0]=
155            ff_h264_lps_range[j*2*64+2*i+1]= lps_range[i][j];
156        }
157
158        ff_h264_mlps_state[128+2*i+0]=
159        ff_h264_mps_state[2*i+0]= 2*mps_state[i]+0;
160        ff_h264_mlps_state[128+2*i+1]=
161        ff_h264_mps_state[2*i+1]= 2*mps_state[i]+1;
162
163        if( i ){
164#ifdef BRANCHLESS_CABAC_DECODER
165            ff_h264_mlps_state[128-2*i-1]= 2*lps_state[i]+0;
166            ff_h264_mlps_state[128-2*i-2]= 2*lps_state[i]+1;
167        }else{
168            ff_h264_mlps_state[128-2*i-1]= 1;
169            ff_h264_mlps_state[128-2*i-2]= 0;
170#else
171            ff_h264_lps_state[2*i+0]= 2*lps_state[i]+0;
172            ff_h264_lps_state[2*i+1]= 2*lps_state[i]+1;
173        }else{
174            ff_h264_lps_state[2*i+0]= 1;
175            ff_h264_lps_state[2*i+1]= 0;
176#endif
177        }
178    }
179}
180
181#ifdef TEST
182#undef random
183#define SIZE 10240
184
185#include "avcodec.h"
186#include "cabac.h"
187
188int main(void){
189    CABACContext c;
190    uint8_t b[9*SIZE];
191    uint8_t r[9*SIZE];
192    int i;
193    uint8_t state[10]= {0};
194
195    ff_init_cabac_encoder(&c, b, SIZE);
196    ff_init_cabac_states(&c);
197
198    for(i=0; i<SIZE; i++){
199        r[i]= random()%7;
200    }
201
202    for(i=0; i<SIZE; i++){
203START_TIMER
204        put_cabac_bypass(&c, r[i]&1);
205STOP_TIMER("put_cabac_bypass")
206    }
207
208    for(i=0; i<SIZE; i++){
209START_TIMER
210        put_cabac(&c, state, r[i]&1);
211STOP_TIMER("put_cabac")
212    }
213
214    for(i=0; i<SIZE; i++){
215START_TIMER
216        put_cabac_u(&c, state, r[i], 6, 3, i&1);
217STOP_TIMER("put_cabac_u")
218    }
219
220    for(i=0; i<SIZE; i++){
221START_TIMER
222        put_cabac_ueg(&c, state, r[i], 3, 0, 1, 2);
223STOP_TIMER("put_cabac_ueg")
224    }
225
226    put_cabac_terminate(&c, 1);
227
228    ff_init_cabac_decoder(&c, b, SIZE);
229
230    memset(state, 0, sizeof(state));
231
232    for(i=0; i<SIZE; i++){
233START_TIMER
234        if( (r[i]&1) != get_cabac_bypass(&c) )
235            av_log(NULL, AV_LOG_ERROR, "CABAC bypass failure at %d\n", i);
236STOP_TIMER("get_cabac_bypass")
237    }
238
239    for(i=0; i<SIZE; i++){
240START_TIMER
241        if( (r[i]&1) != get_cabac(&c, state) )
242            av_log(NULL, AV_LOG_ERROR, "CABAC failure at %d\n", i);
243STOP_TIMER("get_cabac")
244    }
245#if 0
246    for(i=0; i<SIZE; i++){
247START_TIMER
248        if( r[i] != get_cabac_u(&c, state, (i&1) ? 6 : 7, 3, i&1) )
249            av_log(NULL, AV_LOG_ERROR, "CABAC unary (truncated) binarization failure at %d\n", i);
250STOP_TIMER("get_cabac_u")
251    }
252
253    for(i=0; i<SIZE; i++){
254START_TIMER
255        if( r[i] != get_cabac_ueg(&c, state, 3, 0, 1, 2))
256            av_log(NULL, AV_LOG_ERROR, "CABAC unary (truncated) binarization failure at %d\n", i);
257STOP_TIMER("get_cabac_ueg")
258    }
259#endif
260    if(!get_cabac_terminate(&c))
261        av_log(NULL, AV_LOG_ERROR, "where's the Terminator?\n");
262
263    return 0;
264}
265
266#endif /* TEST */
267