libavcodec/cabac.c

   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 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
  33 static 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
  52 uint8_t ff_h264_mlps_state[4*64];
  53 uint8_t ff_h264_lps_range[4*2*64];
  54 uint8_t ff_h264_lps_state[2*64];
  55 uint8_t ff_h264_mps_state[2*64];
  56
  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,
  66 };
  67
  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,
  77 };
  78 #if 0
  79 const 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
  90 const 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  */
 117 void 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  */
 134 void 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
 149 void 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
 188 int 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++){
 203 START_TIMER
 204         put_cabac_bypass(&c, r[i]&1);
 205 STOP_TIMER("put_cabac_bypass")
 206     }
 207
 208     for(i=0; i<SIZE; i++){
 209 START_TIMER
 210         put_cabac(&c, state, r[i]&1);
 211 STOP_TIMER("put_cabac")
 212     }
 213
 214     for(i=0; i<SIZE; i++){
 215 START_TIMER
 216         put_cabac_u(&c, state, r[i], 6, 3, i&1);
 217 STOP_TIMER("put_cabac_u")
 218     }
 219
 220     for(i=0; i<SIZE; i++){
 221 START_TIMER
 222         put_cabac_ueg(&c, state, r[i], 3, 0, 1, 2);
 223 STOP_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++){
 233 START_TIMER
 234         if( (r[i]&1) != get_cabac_bypass(&c) )
 235             av_log(NULL, AV_LOG_ERROR, "CABAC bypass failure at %d\n", i);
 236 STOP_TIMER("get_cabac_bypass")
 237     }
 238
 239     for(i=0; i<SIZE; i++){
 240 START_TIMER
 241         if( (r[i]&1) != get_cabac(&c, state) )
 242             av_log(NULL, AV_LOG_ERROR, "CABAC failure at %d\n", i);
 243 STOP_TIMER("get_cabac")
 244     }
 245 #if 0
 246     for(i=0; i<SIZE; i++){
 247 START_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);
 250 STOP_TIMER("get_cabac_u")
 251     }
 252
 253     for(i=0; i<SIZE; i++){
 254 START_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);
 257 STOP_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 */