2 * H.26L/H.264/AVC/JVT/14496-10/... encoder/decoder
3 * Copyright (c) 2003 Michael Niedermayer <michaelni@gmx.at>
5 * This file is part of FFmpeg.
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.
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.
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
24 * Context Adaptive Binary Arithmetic Coder.
29 #include "libavutil/common.h"
32 #include "cabac_functions.h"
34 static const uint8_t lps_range[64][4]= {
35 {128,176,208,240}, {128,167,197,227}, {128,158,187,216}, {123,150,178,205},
36 {116,142,169,195}, {111,135,160,185}, {105,128,152,175}, {100,122,144,166},
37 { 95,116,137,158}, { 90,110,130,150}, { 85,104,123,142}, { 81, 99,117,135},
38 { 77, 94,111,128}, { 73, 89,105,122}, { 69, 85,100,116}, { 66, 80, 95,110},
39 { 62, 76, 90,104}, { 59, 72, 86, 99}, { 56, 69, 81, 94}, { 53, 65, 77, 89},
40 { 51, 62, 73, 85}, { 48, 59, 69, 80}, { 46, 56, 66, 76}, { 43, 53, 63, 72},
41 { 41, 50, 59, 69}, { 39, 48, 56, 65}, { 37, 45, 54, 62}, { 35, 43, 51, 59},
42 { 33, 41, 48, 56}, { 32, 39, 46, 53}, { 30, 37, 43, 50}, { 29, 35, 41, 48},
43 { 27, 33, 39, 45}, { 26, 31, 37, 43}, { 24, 30, 35, 41}, { 23, 28, 33, 39},
44 { 22, 27, 32, 37}, { 21, 26, 30, 35}, { 20, 24, 29, 33}, { 19, 23, 27, 31},
45 { 18, 22, 26, 30}, { 17, 21, 25, 28}, { 16, 20, 23, 27}, { 15, 19, 22, 25},
46 { 14, 18, 21, 24}, { 14, 17, 20, 23}, { 13, 16, 19, 22}, { 12, 15, 18, 21},
47 { 12, 14, 17, 20}, { 11, 14, 16, 19}, { 11, 13, 15, 18}, { 10, 12, 15, 17},
48 { 10, 12, 14, 16}, { 9, 11, 13, 15}, { 9, 11, 12, 14}, { 8, 10, 12, 14},
49 { 8, 9, 11, 13}, { 7, 9, 11, 12}, { 7, 9, 10, 12}, { 7, 8, 10, 11},
50 { 6, 8, 9, 11}, { 6, 7, 9, 10}, { 6, 7, 8, 9}, { 2, 2, 2, 2},
53 uint8_t ff_h264_mlps_state[4*64];
54 uint8_t ff_h264_lps_range[4*2*64];
55 static uint8_t h264_mps_state[2 * 64];
57 static 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,
68 static 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,
79 const uint8_t ff_h264_norm_shift[512]= {
80 9,8,7,7,6,6,6,6,5,5,5,5,5,5,5,5,
81 4,4,4,4,4,4,4,4,4,4,4,4,4,4,4,4,
82 3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,
83 3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,
84 2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,
85 2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,
86 2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,
87 2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,
88 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,
89 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,
90 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,
91 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,
92 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,
93 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,
94 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,
95 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,
96 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,
97 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,
98 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,
99 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 * @param buf_size size of buf in bits
106 void ff_init_cabac_encoder(CABACContext *c, uint8_t *buf, int buf_size){
107 init_put_bits(&c->pb, buf, buf_size);
111 c->outstanding_count= 0;
112 c->pb.bit_left++; //avoids firstBitFlag
117 * @param buf_size size of buf in bits
119 void ff_init_cabac_decoder(CABACContext *c, const uint8_t *buf, int buf_size){
122 c->bytestream_end= buf + buf_size;
125 c->low = (*c->bytestream++)<<18;
126 c->low+= (*c->bytestream++)<<10;
128 c->low = (*c->bytestream++)<<10;
130 c->low+= ((*c->bytestream++)<<2) + 2;
134 void ff_init_cabac_states(CABACContext *c){
138 for(j=0; j<4; j++){ //FIXME check if this is worth the 1 shift we save
139 ff_h264_lps_range[j*2*64+2*i+0]=
140 ff_h264_lps_range[j*2*64+2*i+1]= lps_range[i][j];
143 ff_h264_mlps_state[128+2*i+0]=
144 h264_mps_state[2 * i + 0] = 2 * mps_state[i] + 0;
145 ff_h264_mlps_state[128+2*i+1]=
146 h264_mps_state[2 * i + 1] = 2 * mps_state[i] + 1;
149 ff_h264_lps_state[2*i+0]=
150 ff_h264_mlps_state[128-2*i-1]= 2*lps_state[i]+0;
151 ff_h264_lps_state[2*i+1]=
152 ff_h264_mlps_state[128-2*i-2]= 2*lps_state[i]+1;
154 ff_h264_lps_state[2*i+0]=
155 ff_h264_mlps_state[128-2*i-1]= 1;
156 ff_h264_lps_state[2*i+1]=
157 ff_h264_mlps_state[128-2*i-2]= 0;
165 #include "libavutil/lfg.h"
169 static inline void put_cabac_bit(CABACContext *c, int b){
170 put_bits(&c->pb, 1, b);
171 for(;c->outstanding_count; c->outstanding_count--){
172 put_bits(&c->pb, 1, 1-b);
176 static inline void renorm_cabac_encoder(CABACContext *c){
177 while(c->range < 0x100){
181 }else if(c->low<0x200){
182 c->outstanding_count++;
194 static void put_cabac(CABACContext *c, uint8_t * const state, int bit){
195 int RangeLPS= ff_h264_lps_range[2*(c->range&0xC0) + *state];
197 if(bit == ((*state)&1)){
198 c->range -= RangeLPS;
199 *state = h264_mps_state[*state];
201 c->low += c->range - RangeLPS;
205 renorm_cabac_encoder(c);
209 * @param bit 0 -> write zero bit, !=0 write one bit
211 static void put_cabac_bypass(CABACContext *c, int bit){
220 }else if(c->low<0x400){
221 c->outstanding_count++;
231 * @return the number of bytes written
233 static int put_cabac_terminate(CABACContext *c, int bit){
237 renorm_cabac_encoder(c);
242 renorm_cabac_encoder(c);
244 assert(c->low <= 0x1FF);
245 put_cabac_bit(c, c->low>>9);
246 put_bits(&c->pb, 2, ((c->low>>7)&3)|1);
248 flush_put_bits(&c->pb); //FIXME FIXME FIXME XXX wrong
251 return (put_bits_count(&c->pb)+7)>>3;
259 uint8_t state[10]= {0};
262 av_lfg_init(&prng, 1);
263 ff_init_cabac_encoder(&c, b, SIZE);
264 ff_init_cabac_states(&c);
266 for(i=0; i<SIZE; i++){
267 if(2*i<SIZE) r[i] = av_lfg_get(&prng) % 7;
268 else r[i] = (i>>8)&1;
271 for(i=0; i<SIZE; i++){
273 put_cabac_bypass(&c, r[i]&1);
274 STOP_TIMER("put_cabac_bypass")
277 for(i=0; i<SIZE; i++){
279 put_cabac(&c, state, r[i]&1);
280 STOP_TIMER("put_cabac")
283 put_cabac_terminate(&c, 1);
285 ff_init_cabac_decoder(&c, b, SIZE);
287 memset(state, 0, sizeof(state));
289 for(i=0; i<SIZE; i++){
291 if( (r[i]&1) != get_cabac_bypass(&c) )
292 av_log(NULL, AV_LOG_ERROR, "CABAC bypass failure at %d\n", i);
293 STOP_TIMER("get_cabac_bypass")
296 for(i=0; i<SIZE; i++){
298 if( (r[i]&1) != get_cabac(&c, state) )
299 av_log(NULL, AV_LOG_ERROR, "CABAC failure at %d\n", i);
300 STOP_TIMER("get_cabac")
302 if(!get_cabac_terminate(&c))
303 av_log(NULL, AV_LOG_ERROR, "where's the Terminator?\n");