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 uint8_t ff_h264_lps_state[2*64];
56 static uint8_t h264_mps_state[2 * 64];
58 static const uint8_t mps_state[64]= {
59 1, 2, 3, 4, 5, 6, 7, 8,
60 9,10,11,12,13,14,15,16,
61 17,18,19,20,21,22,23,24,
62 25,26,27,28,29,30,31,32,
63 33,34,35,36,37,38,39,40,
64 41,42,43,44,45,46,47,48,
65 49,50,51,52,53,54,55,56,
66 57,58,59,60,61,62,62,63,
69 static const uint8_t lps_state[64]= {
70 0, 0, 1, 2, 2, 4, 4, 5,
71 6, 7, 8, 9, 9,11,11,12,
72 13,13,15,15,16,16,18,18,
73 19,19,21,21,22,22,23,24,
74 24,25,26,26,27,27,28,29,
75 29,30,30,30,31,32,32,33,
76 33,33,34,34,35,35,35,36,
77 36,36,37,37,37,38,38,63,
80 const uint8_t ff_h264_norm_shift[512]= {
81 9,8,7,7,6,6,6,6,5,5,5,5,5,5,5,5,
82 4,4,4,4,4,4,4,4,4,4,4,4,4,4,4,4,
83 3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,
84 3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,
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 2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,
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 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,
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 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 * @param buf_size size of buf in bits
107 void ff_init_cabac_encoder(CABACContext *c, uint8_t *buf, int buf_size){
108 init_put_bits(&c->pb, buf, buf_size);
112 c->outstanding_count= 0;
113 c->pb.bit_left++; //avoids firstBitFlag
118 * @param buf_size size of buf in bits
120 void ff_init_cabac_decoder(CABACContext *c, const uint8_t *buf, int buf_size){
123 c->bytestream_end= buf + buf_size;
126 c->low = (*c->bytestream++)<<18;
127 c->low+= (*c->bytestream++)<<10;
129 c->low = (*c->bytestream++)<<10;
131 c->low+= ((*c->bytestream++)<<2) + 2;
135 void ff_init_cabac_states(CABACContext *c){
139 for(j=0; j<4; j++){ //FIXME check if this is worth the 1 shift we save
140 ff_h264_lps_range[j*2*64+2*i+0]=
141 ff_h264_lps_range[j*2*64+2*i+1]= lps_range[i][j];
144 ff_h264_mlps_state[128+2*i+0]=
145 h264_mps_state[2 * i + 0] = 2 * mps_state[i] + 0;
146 ff_h264_mlps_state[128+2*i+1]=
147 h264_mps_state[2 * i + 1] = 2 * mps_state[i] + 1;
150 ff_h264_lps_state[2*i+0]=
151 ff_h264_mlps_state[128-2*i-1]= 2*lps_state[i]+0;
152 ff_h264_lps_state[2*i+1]=
153 ff_h264_mlps_state[128-2*i-2]= 2*lps_state[i]+1;
155 ff_h264_lps_state[2*i+0]=
156 ff_h264_mlps_state[128-2*i-1]= 1;
157 ff_h264_lps_state[2*i+1]=
158 ff_h264_mlps_state[128-2*i-2]= 0;
166 #include "libavutil/lfg.h"
170 static inline void put_cabac_bit(CABACContext *c, int b){
171 put_bits(&c->pb, 1, b);
172 for(;c->outstanding_count; c->outstanding_count--){
173 put_bits(&c->pb, 1, 1-b);
177 static inline void renorm_cabac_encoder(CABACContext *c){
178 while(c->range < 0x100){
182 }else if(c->low<0x200){
183 c->outstanding_count++;
195 static void put_cabac(CABACContext *c, uint8_t * const state, int bit){
196 int RangeLPS= ff_h264_lps_range[2*(c->range&0xC0) + *state];
198 if(bit == ((*state)&1)){
199 c->range -= RangeLPS;
200 *state = h264_mps_state[*state];
202 c->low += c->range - RangeLPS;
204 *state= ff_h264_lps_state[*state];
207 renorm_cabac_encoder(c);
211 * @param bit 0 -> write zero bit, !=0 write one bit
213 static void put_cabac_bypass(CABACContext *c, int bit){
222 }else if(c->low<0x400){
223 c->outstanding_count++;
233 * @return the number of bytes written
235 static int put_cabac_terminate(CABACContext *c, int bit){
239 renorm_cabac_encoder(c);
244 renorm_cabac_encoder(c);
246 assert(c->low <= 0x1FF);
247 put_cabac_bit(c, c->low>>9);
248 put_bits(&c->pb, 2, ((c->low>>7)&3)|1);
250 flush_put_bits(&c->pb); //FIXME FIXME FIXME XXX wrong
253 return (put_bits_count(&c->pb)+7)>>3;
261 uint8_t state[10]= {0};
264 av_lfg_init(&prng, 1);
265 ff_init_cabac_encoder(&c, b, SIZE);
266 ff_init_cabac_states(&c);
268 for(i=0; i<SIZE; i++){
269 if(2*i<SIZE) r[i] = av_lfg_get(&prng) % 7;
270 else r[i] = (i>>8)&1;
273 for(i=0; i<SIZE; i++){
275 put_cabac_bypass(&c, r[i]&1);
276 STOP_TIMER("put_cabac_bypass")
279 for(i=0; i<SIZE; i++){
281 put_cabac(&c, state, r[i]&1);
282 STOP_TIMER("put_cabac")
285 put_cabac_terminate(&c, 1);
287 ff_init_cabac_decoder(&c, b, SIZE);
289 memset(state, 0, sizeof(state));
291 for(i=0; i<SIZE; i++){
293 if( (r[i]&1) != get_cabac_bypass(&c) )
294 av_log(NULL, AV_LOG_ERROR, "CABAC bypass failure at %d\n", i);
295 STOP_TIMER("get_cabac_bypass")
298 for(i=0; i<SIZE; i++){
300 if( (r[i]&1) != get_cabac(&c, state) )
301 av_log(NULL, AV_LOG_ERROR, "CABAC failure at %d\n", i);
302 STOP_TIMER("get_cabac")
304 if(!get_cabac_terminate(&c))
305 av_log(NULL, AV_LOG_ERROR, "where's the Terminator?\n");