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/*
* H.26L/H.264/AVC/JVT/14496-10/... encoder/decoder
* Copyright (c) 2003 Michael Niedermayer <michaelni@gmx.at>
*
* This file is part of FFmpeg.
*
* FFmpeg is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public
* License as published by the Free Software Foundation; either
* version 2.1 of the License, or (at your option) any later version.
*
* FFmpeg is distributed in the hope that it will be useful,
* 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
* License along with FFmpeg; if not, write to the Free Software
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
*/
/**
* @file
* Context Adaptive Binary Arithmetic Coder.
*/
#include <string.h>
#include "libavutil/common.h"
#include "libavutil/timer.h"
#include "get_bits.h"
#include "cabac.h"
#include "cabac_functions.h"
#include "cabac_tablegen.h"
/**
*
* @param buf_size size of buf in bits
*/
void ff_init_cabac_encoder(CABACContext *c, uint8_t *buf, int buf_size){
init_put_bits(&c->pb, buf, buf_size);
c->low= 0;
c->range= 0x1FE;
c->outstanding_count= 0;
c->pb.bit_left++; //avoids firstBitFlag
}
/**
*
* @param buf_size size of buf in bits
*/
int ff_init_cabac_decoder(CABACContext *c, const uint8_t *buf, int buf_size){
c->bytestream_start=
c->bytestream= buf;
c->bytestream_end= buf + buf_size;
#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;
c->range= 0x1FE;
if ((c->range<<(CABAC_BITS+1)) < c->low)
return AVERROR_INVALIDDATA;
return 0;
}
void ff_init_cabac_states(void)
{
static int initialized = 0;
if (initialized)
return;
cabac_tableinit();
initialized = 1;
}
#ifdef TEST
#define SIZE 10240
#include "libavutil/lfg.h"
#include "avcodec.h"
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;
}
}
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;
*state = ff_h264_mlps_state[128 + *state];
}else{
c->low += c->range - RangeLPS;
c->range = RangeLPS;
*state= ff_h264_mlps_state[127 - *state];
}
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);
av_assert0(c->low <= 0x1FF);
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;
}
int main(void){
CABACContext c;
uint8_t b[9*SIZE];
uint8_t r[9*SIZE];
int i, ret = 0;
uint8_t state[10]= {0};
AVLFG prng;
av_lfg_init(&prng, 1);
ff_init_cabac_encoder(&c, b, SIZE);
ff_init_cabac_states();
for(i=0; i<SIZE; i++){
if(2*i<SIZE) r[i] = av_lfg_get(&prng) % 7;
else r[i] = (i>>8)&1;
}
for(i=0; i<SIZE; i++){
put_cabac_bypass(&c, r[i]&1);
}
for(i=0; i<SIZE; i++){
put_cabac(&c, state, r[i]&1);
}
put_cabac_terminate(&c, 1);
ff_init_cabac_decoder(&c, b, SIZE);
memset(state, 0, sizeof(state));
for(i=0; i<SIZE; i++){
if( (r[i]&1) != get_cabac_bypass(&c) ) {
av_log(NULL, AV_LOG_ERROR, "CABAC bypass failure at %d\n", i);
ret = 1;
}
}
for(i=0; i<SIZE; i++){
if( (r[i]&1) != get_cabac_noinline(&c, state) ) {
av_log(NULL, AV_LOG_ERROR, "CABAC failure at %d\n", i);
ret = 1;
}
}
if(!get_cabac_terminate(&c)) {
av_log(NULL, AV_LOG_ERROR, "where's the Terminator?\n");
ret = 1;
}
return ret;
}
#endif /* TEST */
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