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"
30 #include "libavutil/timer.h"
33 #include "cabac_functions.h"
35 #include "cabac_tablegen.h"
39 * @param buf_size size of buf in bits
41 void ff_init_cabac_encoder(CABACContext *c, uint8_t *buf, int buf_size){
42 init_put_bits(&c->pb, buf, buf_size);
46 c->outstanding_count= 0;
47 c->pb.bit_left++; //avoids firstBitFlag
52 * @param buf_size size of buf in bits
54 void ff_init_cabac_decoder(CABACContext *c, const uint8_t *buf, int buf_size){
57 c->bytestream_end= buf + buf_size;
60 c->low = (*c->bytestream++)<<18;
61 c->low+= (*c->bytestream++)<<10;
63 c->low = (*c->bytestream++)<<10;
65 c->low+= ((*c->bytestream++)<<2) + 2;
69 void ff_init_cabac_states(void)
71 static int initialized = 0;
84 #include "libavutil/lfg.h"
87 static inline void put_cabac_bit(CABACContext *c, int b){
88 put_bits(&c->pb, 1, b);
89 for(;c->outstanding_count; c->outstanding_count--){
90 put_bits(&c->pb, 1, 1-b);
94 static inline void renorm_cabac_encoder(CABACContext *c){
95 while(c->range < 0x100){
99 }else if(c->low<0x200){
100 c->outstanding_count++;
112 static void put_cabac(CABACContext *c, uint8_t * const state, int bit){
113 int RangeLPS= ff_h264_lps_range[2*(c->range&0xC0) + *state];
115 if(bit == ((*state)&1)){
116 c->range -= RangeLPS;
117 *state = ff_h264_mlps_state[128 + *state];
119 c->low += c->range - RangeLPS;
121 *state= ff_h264_mlps_state[127 - *state];
124 renorm_cabac_encoder(c);
128 * @param bit 0 -> write zero bit, !=0 write one bit
130 static void put_cabac_bypass(CABACContext *c, int bit){
139 }else if(c->low<0x400){
140 c->outstanding_count++;
150 * @return the number of bytes written
152 static int put_cabac_terminate(CABACContext *c, int bit){
156 renorm_cabac_encoder(c);
161 renorm_cabac_encoder(c);
163 av_assert0(c->low <= 0x1FF);
164 put_cabac_bit(c, c->low>>9);
165 put_bits(&c->pb, 2, ((c->low>>7)&3)|1);
167 flush_put_bits(&c->pb); //FIXME FIXME FIXME XXX wrong
170 return (put_bits_count(&c->pb)+7)>>3;
178 uint8_t state[10]= {0};
181 av_lfg_init(&prng, 1);
182 ff_init_cabac_encoder(&c, b, SIZE);
183 ff_init_cabac_states();
185 for(i=0; i<SIZE; i++){
186 if(2*i<SIZE) r[i] = av_lfg_get(&prng) % 7;
187 else r[i] = (i>>8)&1;
190 for(i=0; i<SIZE; i++){
191 put_cabac_bypass(&c, r[i]&1);
194 for(i=0; i<SIZE; i++){
195 put_cabac(&c, state, r[i]&1);
198 put_cabac_terminate(&c, 1);
200 ff_init_cabac_decoder(&c, b, SIZE);
202 memset(state, 0, sizeof(state));
204 for(i=0; i<SIZE; i++){
205 if( (r[i]&1) != get_cabac_bypass(&c) ) {
206 av_log(NULL, AV_LOG_ERROR, "CABAC bypass failure at %d\n", i);
211 for(i=0; i<SIZE; i++){
212 if( (r[i]&1) != get_cabac_noinline(&c, state) ) {
213 av_log(NULL, AV_LOG_ERROR, "CABAC failure at %d\n", i);
217 if(!get_cabac_terminate(&c)) {
218 av_log(NULL, AV_LOG_ERROR, "where's the Terminator?\n");