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 22/** 23 * @file 24 * Context Adaptive Binary Arithmetic Coder. 25 */ 26 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 34static 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}, 51}; 52 53uint8_t ff_h264_mlps_state[4*64]; 54uint8_t ff_h264_lps_range[4*2*64]; 55static uint8_t 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 79const 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, 100}; 101 102/** 103 * 104 * @param buf_size size of buf in bits 105 */ 106void ff_init_cabac_encoder(CABACContext *c, uint8_t *buf, int buf_size){ 107 init_put_bits(&c->pb, buf, buf_size); 108 109 c->low= 0; 110 c->range= 0x1FE; 111 c->outstanding_count= 0; 112 c->pb.bit_left++; //avoids firstBitFlag 113} 114 115/** 116 * 117 * @param buf_size size of buf in bits 118 */ 119void ff_init_cabac_decoder(CABACContext *c, const uint8_t *buf, int buf_size){ 120 c->bytestream_start= 121 c->bytestream= buf; 122 c->bytestream_end= buf + buf_size; 123 124#if CABAC_BITS == 16 125 c->low = (*c->bytestream++)<<18; 126 c->low+= (*c->bytestream++)<<10; 127#else 128 c->low = (*c->bytestream++)<<10; 129#endif 130 c->low+= ((*c->bytestream++)<<2) + 2; 131 c->range= 0x1FE; 132} 133 134void ff_init_cabac_states(CABACContext *c){ 135 int i, j; 136 137 for(i=0; i<64; i++){ 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]; 141 } 142 143 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; 147 148 if( i ){ 149 ff_h264_mlps_state[128-2*i-1]= 2*lps_state[i]+0; 150 ff_h264_mlps_state[128-2*i-2]= 2*lps_state[i]+1; 151 }else{ 152 ff_h264_mlps_state[128-2*i-1]= 1; 153 ff_h264_mlps_state[128-2*i-2]= 0; 154 } 155 } 156} 157 158#ifdef TEST 159#define SIZE 10240 160 161#include "libavutil/lfg.h" 162#include "avcodec.h" 163#include "cabac.h" 164 165static inline void put_cabac_bit(CABACContext *c, int b){ 166 put_bits(&c->pb, 1, b); 167 for(;c->outstanding_count; c->outstanding_count--){ 168 put_bits(&c->pb, 1, 1-b); 169 } 170} 171 172static inline void renorm_cabac_encoder(CABACContext *c){ 173 while(c->range < 0x100){ 174 //FIXME optimize 175 if(c->low<0x100){ 176 put_cabac_bit(c, 0); 177 }else if(c->low<0x200){ 178 c->outstanding_count++; 179 c->low -= 0x100; 180 }else{ 181 put_cabac_bit(c, 1); 182 c->low -= 0x200; 183 } 184 185 c->range+= c->range; 186 c->low += c->low; 187 } 188} 189 190static void put_cabac(CABACContext *c, uint8_t * const state, int bit){ 191 int RangeLPS= ff_h264_lps_range[2*(c->range&0xC0) + *state]; 192 193 if(bit == ((*state)&1)){ 194 c->range -= RangeLPS; 195 *state = h264_mps_state[*state]; 196 }else{ 197 c->low += c->range - RangeLPS; 198 c->range = RangeLPS; 199 } 200 201 renorm_cabac_encoder(c); 202} 203 204/** 205 * @param bit 0 -> write zero bit, !=0 write one bit 206 */ 207static void put_cabac_bypass(CABACContext *c, int bit){ 208 c->low += c->low; 209 210 if(bit){ 211 c->low += c->range; 212 } 213//FIXME optimize 214 if(c->low<0x200){ 215 put_cabac_bit(c, 0); 216 }else if(c->low<0x400){ 217 c->outstanding_count++; 218 c->low -= 0x200; 219 }else{ 220 put_cabac_bit(c, 1); 221 c->low -= 0x400; 222 } 223} 224 225/** 226 * 227 * @return the number of bytes written 228 */ 229static int put_cabac_terminate(CABACContext *c, int bit){ 230 c->range -= 2; 231 232 if(!bit){ 233 renorm_cabac_encoder(c); 234 }else{ 235 c->low += c->range; 236 c->range= 2; 237 238 renorm_cabac_encoder(c); 239 240 assert(c->low <= 0x1FF); 241 put_cabac_bit(c, c->low>>9); 242 put_bits(&c->pb, 2, ((c->low>>7)&3)|1); 243 244 flush_put_bits(&c->pb); //FIXME FIXME FIXME XXX wrong 245 } 246 247 return (put_bits_count(&c->pb)+7)>>3; 248} 249 250int main(void){ 251 CABACContext c; 252 uint8_t b[9*SIZE]; 253 uint8_t r[9*SIZE]; 254 int i; 255 uint8_t state[10]= {0}; 256 AVLFG prng; 257 258 av_lfg_init(&prng, 1); 259 ff_init_cabac_encoder(&c, b, SIZE); 260 ff_init_cabac_states(&c); 261 262 for(i=0; i<SIZE; i++){ 263 r[i] = av_lfg_get(&prng) % 7; 264 } 265 266 for(i=0; i<SIZE; i++){ 267START_TIMER 268 put_cabac_bypass(&c, r[i]&1); 269STOP_TIMER("put_cabac_bypass") 270 } 271 272 for(i=0; i<SIZE; i++){ 273START_TIMER 274 put_cabac(&c, state, r[i]&1); 275STOP_TIMER("put_cabac") 276 } 277 278 put_cabac_terminate(&c, 1); 279 280 ff_init_cabac_decoder(&c, b, SIZE); 281 282 memset(state, 0, sizeof(state)); 283 284 for(i=0; i<SIZE; i++){ 285START_TIMER 286 if( (r[i]&1) != get_cabac_bypass(&c) ) 287 av_log(NULL, AV_LOG_ERROR, "CABAC bypass failure at %d\n", i); 288STOP_TIMER("get_cabac_bypass") 289 } 290 291 for(i=0; i<SIZE; i++){ 292START_TIMER 293 if( (r[i]&1) != get_cabac(&c, state) ) 294 av_log(NULL, AV_LOG_ERROR, "CABAC failure at %d\n", i); 295STOP_TIMER("get_cabac") 296 } 297 if(!get_cabac_terminate(&c)) 298 av_log(NULL, AV_LOG_ERROR, "where's the Terminator?\n"); 299 300 return 0; 301} 302 303#endif /* TEST */ 304