• Main Page
  • Related Pages
  • Modules
  • Data Structures
  • Files
  • File List
  • Globals

libavcodec/cabac.c

Go to the documentation of this file.
00001 /*
00002  * H.26L/H.264/AVC/JVT/14496-10/... encoder/decoder
00003  * Copyright (c) 2003 Michael Niedermayer <michaelni@gmx.at>
00004  *
00005  * This file is part of FFmpeg.
00006  *
00007  * FFmpeg is free software; you can redistribute it and/or
00008  * modify it under the terms of the GNU Lesser General Public
00009  * License as published by the Free Software Foundation; either
00010  * version 2.1 of the License, or (at your option) any later version.
00011  *
00012  * FFmpeg is distributed in the hope that it will be useful,
00013  * but WITHOUT ANY WARRANTY; without even the implied warranty of
00014  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
00015  * Lesser General Public License for more details.
00016  *
00017  * You should have received a copy of the GNU Lesser General Public
00018  * License along with FFmpeg; if not, write to the Free Software
00019  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
00020  */
00021 
00027 #include <string.h>
00028 
00029 #include "libavutil/common.h"
00030 #include "get_bits.h"
00031 #include "cabac.h"
00032 
00033 static const uint8_t lps_range[64][4]= {
00034 {128,176,208,240}, {128,167,197,227}, {128,158,187,216}, {123,150,178,205},
00035 {116,142,169,195}, {111,135,160,185}, {105,128,152,175}, {100,122,144,166},
00036 { 95,116,137,158}, { 90,110,130,150}, { 85,104,123,142}, { 81, 99,117,135},
00037 { 77, 94,111,128}, { 73, 89,105,122}, { 69, 85,100,116}, { 66, 80, 95,110},
00038 { 62, 76, 90,104}, { 59, 72, 86, 99}, { 56, 69, 81, 94}, { 53, 65, 77, 89},
00039 { 51, 62, 73, 85}, { 48, 59, 69, 80}, { 46, 56, 66, 76}, { 43, 53, 63, 72},
00040 { 41, 50, 59, 69}, { 39, 48, 56, 65}, { 37, 45, 54, 62}, { 35, 43, 51, 59},
00041 { 33, 41, 48, 56}, { 32, 39, 46, 53}, { 30, 37, 43, 50}, { 29, 35, 41, 48},
00042 { 27, 33, 39, 45}, { 26, 31, 37, 43}, { 24, 30, 35, 41}, { 23, 28, 33, 39},
00043 { 22, 27, 32, 37}, { 21, 26, 30, 35}, { 20, 24, 29, 33}, { 19, 23, 27, 31},
00044 { 18, 22, 26, 30}, { 17, 21, 25, 28}, { 16, 20, 23, 27}, { 15, 19, 22, 25},
00045 { 14, 18, 21, 24}, { 14, 17, 20, 23}, { 13, 16, 19, 22}, { 12, 15, 18, 21},
00046 { 12, 14, 17, 20}, { 11, 14, 16, 19}, { 11, 13, 15, 18}, { 10, 12, 15, 17},
00047 { 10, 12, 14, 16}, {  9, 11, 13, 15}, {  9, 11, 12, 14}, {  8, 10, 12, 14},
00048 {  8,  9, 11, 13}, {  7,  9, 11, 12}, {  7,  9, 10, 12}, {  7,  8, 10, 11},
00049 {  6,  8,  9, 11}, {  6,  7,  9, 10}, {  6,  7,  8,  9}, {  2,  2,  2,  2},
00050 };
00051 
00052 uint8_t ff_h264_mlps_state[4*64];
00053 uint8_t ff_h264_lps_range[4*2*64];
00054 uint8_t ff_h264_lps_state[2*64];
00055 uint8_t ff_h264_mps_state[2*64];
00056 
00057 static const uint8_t mps_state[64]= {
00058   1, 2, 3, 4, 5, 6, 7, 8,
00059   9,10,11,12,13,14,15,16,
00060  17,18,19,20,21,22,23,24,
00061  25,26,27,28,29,30,31,32,
00062  33,34,35,36,37,38,39,40,
00063  41,42,43,44,45,46,47,48,
00064  49,50,51,52,53,54,55,56,
00065  57,58,59,60,61,62,62,63,
00066 };
00067 
00068 static const uint8_t lps_state[64]= {
00069   0, 0, 1, 2, 2, 4, 4, 5,
00070   6, 7, 8, 9, 9,11,11,12,
00071  13,13,15,15,16,16,18,18,
00072  19,19,21,21,22,22,23,24,
00073  24,25,26,26,27,27,28,29,
00074  29,30,30,30,31,32,32,33,
00075  33,33,34,34,35,35,35,36,
00076  36,36,37,37,37,38,38,63,
00077 };
00078 #if 0
00079 const uint8_t ff_h264_norm_shift_old[128]= {
00080  7,6,5,5,4,4,4,4,3,3,3,3,3,3,3,3,
00081  2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,
00082  1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,
00083  1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,
00084  0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,
00085  0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,
00086  0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,
00087  0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,
00088 };
00089 #endif
00090 const uint8_t ff_h264_norm_shift[512]= {
00091  9,8,7,7,6,6,6,6,5,5,5,5,5,5,5,5,
00092  4,4,4,4,4,4,4,4,4,4,4,4,4,4,4,4,
00093  3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,
00094  3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,
00095  2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,
00096  2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,
00097  2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,
00098  2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,
00099  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,
00100  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,
00101  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,
00102  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,
00103  0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,
00104  0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,
00105  0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,
00106  0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,
00107  0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,
00108  0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,
00109  0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,
00110  0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,
00111 };
00112 
00117 void ff_init_cabac_encoder(CABACContext *c, uint8_t *buf, int buf_size){
00118     init_put_bits(&c->pb, buf, buf_size);
00119 
00120     c->low= 0;
00121     c->range= 0x1FE;
00122     c->outstanding_count= 0;
00123 #ifdef STRICT_LIMITS
00124     c->sym_count =0;
00125 #endif
00126 
00127     c->pb.bit_left++; //avoids firstBitFlag
00128 }
00129 
00134 void ff_init_cabac_decoder(CABACContext *c, const uint8_t *buf, int buf_size){
00135     c->bytestream_start=
00136     c->bytestream= buf;
00137     c->bytestream_end= buf + buf_size;
00138 
00139 #if CABAC_BITS == 16
00140     c->low =  (*c->bytestream++)<<18;
00141     c->low+=  (*c->bytestream++)<<10;
00142 #else
00143     c->low =  (*c->bytestream++)<<10;
00144 #endif
00145     c->low+= ((*c->bytestream++)<<2) + 2;
00146     c->range= 0x1FE;
00147 }
00148 
00149 void ff_init_cabac_states(CABACContext *c){
00150     int i, j;
00151 
00152     for(i=0; i<64; i++){
00153         for(j=0; j<4; j++){ //FIXME check if this is worth the 1 shift we save
00154             ff_h264_lps_range[j*2*64+2*i+0]=
00155             ff_h264_lps_range[j*2*64+2*i+1]= lps_range[i][j];
00156         }
00157 
00158         ff_h264_mlps_state[128+2*i+0]=
00159         ff_h264_mps_state[2*i+0]= 2*mps_state[i]+0;
00160         ff_h264_mlps_state[128+2*i+1]=
00161         ff_h264_mps_state[2*i+1]= 2*mps_state[i]+1;
00162 
00163         if( i ){
00164 #ifdef BRANCHLESS_CABAC_DECODER
00165             ff_h264_mlps_state[128-2*i-1]= 2*lps_state[i]+0;
00166             ff_h264_mlps_state[128-2*i-2]= 2*lps_state[i]+1;
00167         }else{
00168             ff_h264_mlps_state[128-2*i-1]= 1;
00169             ff_h264_mlps_state[128-2*i-2]= 0;
00170 #else
00171             ff_h264_lps_state[2*i+0]= 2*lps_state[i]+0;
00172             ff_h264_lps_state[2*i+1]= 2*lps_state[i]+1;
00173         }else{
00174             ff_h264_lps_state[2*i+0]= 1;
00175             ff_h264_lps_state[2*i+1]= 0;
00176 #endif
00177         }
00178     }
00179 }
00180 
00181 #ifdef TEST
00182 #define SIZE 10240
00183 
00184 #include "libavutil/lfg.h"
00185 #include "avcodec.h"
00186 #include "cabac.h"
00187 
00188 int main(void){
00189     CABACContext c;
00190     uint8_t b[9*SIZE];
00191     uint8_t r[9*SIZE];
00192     int i;
00193     uint8_t state[10]= {0};
00194     AVLFG prng;
00195 
00196     av_lfg_init(&prng, 1);
00197     ff_init_cabac_encoder(&c, b, SIZE);
00198     ff_init_cabac_states(&c);
00199 
00200     for(i=0; i<SIZE; i++){
00201         r[i] = av_lfg_get(&prng) % 7;
00202     }
00203 
00204     for(i=0; i<SIZE; i++){
00205 START_TIMER
00206         put_cabac_bypass(&c, r[i]&1);
00207 STOP_TIMER("put_cabac_bypass")
00208     }
00209 
00210     for(i=0; i<SIZE; i++){
00211 START_TIMER
00212         put_cabac(&c, state, r[i]&1);
00213 STOP_TIMER("put_cabac")
00214     }
00215 
00216     for(i=0; i<SIZE; i++){
00217 START_TIMER
00218         put_cabac_u(&c, state, r[i], 6, 3, i&1);
00219 STOP_TIMER("put_cabac_u")
00220     }
00221 
00222     for(i=0; i<SIZE; i++){
00223 START_TIMER
00224         put_cabac_ueg(&c, state, r[i], 3, 0, 1, 2);
00225 STOP_TIMER("put_cabac_ueg")
00226     }
00227 
00228     put_cabac_terminate(&c, 1);
00229 
00230     ff_init_cabac_decoder(&c, b, SIZE);
00231 
00232     memset(state, 0, sizeof(state));
00233 
00234     for(i=0; i<SIZE; i++){
00235 START_TIMER
00236         if( (r[i]&1) != get_cabac_bypass(&c) )
00237             av_log(NULL, AV_LOG_ERROR, "CABAC bypass failure at %d\n", i);
00238 STOP_TIMER("get_cabac_bypass")
00239     }
00240 
00241     for(i=0; i<SIZE; i++){
00242 START_TIMER
00243         if( (r[i]&1) != get_cabac(&c, state) )
00244             av_log(NULL, AV_LOG_ERROR, "CABAC failure at %d\n", i);
00245 STOP_TIMER("get_cabac")
00246     }
00247 #if 0
00248     for(i=0; i<SIZE; i++){
00249 START_TIMER
00250         if( r[i] != get_cabac_u(&c, state, (i&1) ? 6 : 7, 3, i&1) )
00251             av_log(NULL, AV_LOG_ERROR, "CABAC unary (truncated) binarization failure at %d\n", i);
00252 STOP_TIMER("get_cabac_u")
00253     }
00254 
00255     for(i=0; i<SIZE; i++){
00256 START_TIMER
00257         if( r[i] != get_cabac_ueg(&c, state, 3, 0, 1, 2))
00258             av_log(NULL, AV_LOG_ERROR, "CABAC unary (truncated) binarization failure at %d\n", i);
00259 STOP_TIMER("get_cabac_ueg")
00260     }
00261 #endif
00262     if(!get_cabac_terminate(&c))
00263         av_log(NULL, AV_LOG_ERROR, "where's the Terminator?\n");
00264 
00265     return 0;
00266 }
00267 
00268 #endif /* TEST */

Generated on Fri Sep 16 2011 17:17:34 for FFmpeg by  doxygen 1.7.1