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/*
* H.26L/H.264/AVC/JVT/14496-10/... encoder/decoder
* Copyright (c) 2003 Michael Niedermayer <michaelni@gmx.at>
* |
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* This file is part of FFmpeg.
*
* FFmpeg is free software; you can redistribute it and/or |
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* modify it under the terms of the GNU Lesser General Public
* License as published by the Free Software Foundation; either |
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* version 2.1 of the License, or (at your option) any later version. |
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* |
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* FFmpeg is distributed in the hope that it will be useful, |
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public |
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* License along with FFmpeg; if not, write to the Free Software |
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* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA |
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*/
/** |
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* @file |
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* Context Adaptive Binary Arithmetic Coder.
*/
#include <string.h>
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#include "libavutil/common.h" |
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#include "libavutil/timer.h" |
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#include "get_bits.h" |
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#include "cabac.h" |
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#include "cabac_functions.h" |
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|
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#include "cabac_tablegen.h" |
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|
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/**
*
* @param buf_size size of buf in bits
*/
void ff_init_cabac_encoder(CABACContext *c, uint8_t *buf, int buf_size){ |
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init_put_bits(&c->pb, buf, buf_size); |
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c->low= 0;
c->range= 0x1FE;
c->outstanding_count= 0;
c->pb.bit_left++; //avoids firstBitFlag
}
/**
*
* @param buf_size size of buf in bits
*/ |
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void ff_init_cabac_decoder(CABACContext *c, const uint8_t *buf, int buf_size){ |
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c->bytestream_start= |
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c->bytestream= buf; |
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c->bytestream_end= buf + buf_size; |
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|
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#if CABAC_BITS == 16
c->low = (*c->bytestream++)<<18;
c->low+= (*c->bytestream++)<<10;
#else
c->low = (*c->bytestream++)<<10;
#endif
c->low+= ((*c->bytestream++)<<2) + 2; |
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c->range= 0x1FE; |
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}
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void ff_init_cabac_states(void)
{ |
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static int initialized = 0;
if (initialized)
return; |
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|
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cabac_tableinit(); |
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initialized = 1; |
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}
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#ifdef TEST |
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#define SIZE 10240 |
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|
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#include "libavutil/lfg.h" |
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#include "avcodec.h"
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static inline void put_cabac_bit(CABACContext *c, int b){
put_bits(&c->pb, 1, b);
for(;c->outstanding_count; c->outstanding_count--){
put_bits(&c->pb, 1, 1-b);
}
}
static inline void renorm_cabac_encoder(CABACContext *c){
while(c->range < 0x100){
//FIXME optimize
if(c->low<0x100){
put_cabac_bit(c, 0);
}else if(c->low<0x200){
c->outstanding_count++;
c->low -= 0x100;
}else{
put_cabac_bit(c, 1);
c->low -= 0x200;
}
c->range+= c->range;
c->low += c->low;
}
}
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static void put_cabac(CABACContext *c, uint8_t * const state, int bit){
int RangeLPS= ff_h264_lps_range[2*(c->range&0xC0) + *state];
if(bit == ((*state)&1)){
c->range -= RangeLPS; |
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*state = ff_h264_mlps_state[128 + *state]; |
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}else{
c->low += c->range - RangeLPS;
c->range = RangeLPS; |
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*state= ff_h264_mlps_state[127 - *state]; |
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}
renorm_cabac_encoder(c);
}
/**
* @param bit 0 -> write zero bit, !=0 write one bit
*/
static void put_cabac_bypass(CABACContext *c, int bit){
c->low += c->low;
if(bit){
c->low += c->range;
}
//FIXME optimize
if(c->low<0x200){
put_cabac_bit(c, 0);
}else if(c->low<0x400){
c->outstanding_count++;
c->low -= 0x200;
}else{
put_cabac_bit(c, 1);
c->low -= 0x400;
}
}
/**
*
* @return the number of bytes written
*/
static int put_cabac_terminate(CABACContext *c, int bit){
c->range -= 2;
if(!bit){
renorm_cabac_encoder(c);
}else{
c->low += c->range;
c->range= 2;
renorm_cabac_encoder(c);
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av_assert0(c->low <= 0x1FF); |
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put_cabac_bit(c, c->low>>9);
put_bits(&c->pb, 2, ((c->low>>7)&3)|1);
flush_put_bits(&c->pb); //FIXME FIXME FIXME XXX wrong
}
return (put_bits_count(&c->pb)+7)>>3;
}
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int main(void){ |
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CABACContext c;
uint8_t b[9*SIZE]; |
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uint8_t r[9*SIZE]; |
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int i; |
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uint8_t state[10]= {0}; |
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AVLFG prng; |
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|
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av_lfg_init(&prng, 1); |
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ff_init_cabac_encoder(&c, b, SIZE); |
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ff_init_cabac_states(); |
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|
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for(i=0; i<SIZE; i++){ |
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if(2*i<SIZE) r[i] = av_lfg_get(&prng) % 7;
else r[i] = (i>>8)&1; |
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} |
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|
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for(i=0; i<SIZE; i++){
START_TIMER |
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put_cabac_bypass(&c, r[i]&1); |
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STOP_TIMER("put_cabac_bypass")
} |
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|
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for(i=0; i<SIZE; i++){
START_TIMER |
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put_cabac(&c, state, r[i]&1); |
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STOP_TIMER("put_cabac")
}
put_cabac_terminate(&c, 1); |
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|
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ff_init_cabac_decoder(&c, b, SIZE); |
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memset(state, 0, sizeof(state)); |
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for(i=0; i<SIZE; i++){
START_TIMER |
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if( (r[i]&1) != get_cabac_bypass(&c) ) |
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av_log(NULL, AV_LOG_ERROR, "CABAC bypass failure at %d\n", i); |
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STOP_TIMER("get_cabac_bypass")
} |
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|
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for(i=0; i<SIZE; i++){
START_TIMER |
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if( (r[i]&1) != get_cabac_noinline(&c, state) ) |
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av_log(NULL, AV_LOG_ERROR, "CABAC failure at %d\n", i); |
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STOP_TIMER("get_cabac")
}
if(!get_cabac_terminate(&c)) |
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av_log(NULL, AV_LOG_ERROR, "where's the Terminator?\n"); |
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|
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return 0;
}
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#endif /* TEST */ |